diff --git a/teensy/FS.h b/teensy/FS.h
index b4ea60d0..dd8c43af 100644
--- a/teensy/FS.h
+++ b/teensy/FS.h
@@ -265,6 +265,7 @@ class FS
 {
 public:
 	FS() {}
+	virtual ~FS() {}
 	virtual File open(const char *filename, uint8_t mode = FILE_READ) = 0;
 	virtual bool exists(const char *filepath) = 0;
 	virtual bool mkdir(const char *filepath) = 0;
diff --git a/teensy3/FS.h b/teensy3/FS.h
index 5672f38c..71e3726a 100644
--- a/teensy3/FS.h
+++ b/teensy3/FS.h
@@ -271,6 +271,7 @@ class FS
 {
 public:
 	FS() {}
+	virtual ~FS() {}
 	virtual File open(const char *filename, uint8_t mode = FILE_READ) = 0;
 	virtual bool exists(const char *filepath) = 0;
 	virtual bool mkdir(const char *filepath) = 0;
diff --git a/teensy3/HardwareSerial.h b/teensy3/HardwareSerial.h
index afa16d7a..f6dd5703 100644
--- a/teensy3/HardwareSerial.h
+++ b/teensy3/HardwareSerial.h
@@ -282,10 +282,7 @@ class HardwareSerial : public Stream
 	#else //(__MK64FX512__) || defined(__MK66FX1M0__) 
 	enum {CNT_HARDWARE_SERIAL = 3};
 	#endif
-	virtual void begin(uint32_t baud);
-	virtual void begin(uint32_t baud, uint32_t format) {
-					  serial_begin(BAUD2DIV(baud));
-					  serial_format(format); }
+	virtual void begin(uint32_t baud, uint32_t format=(uint32_t)-1);
 	virtual void end(void)		{ serial_end(); }
 	virtual void transmitterEnable(uint8_t pin) { serial_set_transmit_pin(pin); }
 	virtual void setRX(uint8_t pin) { serial_set_rx(pin); }
@@ -336,10 +333,7 @@ class HardwareSerial2 : public HardwareSerial
 {
 public:
 	constexpr HardwareSerial2(void (* const se)()) : HardwareSerial(se) {}
-	virtual void begin(uint32_t baud);
-	virtual void begin(uint32_t baud, uint32_t format) {
-					  serial2_begin(BAUD2DIV2(baud));
-					  serial2_format(format); }
+	virtual void begin(uint32_t baud, uint32_t format=(uint32_t)-1);
 	virtual void end(void)		{ serial2_end(); }
 	virtual void transmitterEnable(uint8_t pin) { serial2_set_transmit_pin(pin); }
 	virtual void setRX(uint8_t pin) { serial2_set_rx(pin); }
@@ -375,10 +369,7 @@ class HardwareSerial3 : public HardwareSerial
 {
 public:
 	constexpr HardwareSerial3(void (* const se)()) : HardwareSerial(se) {}
-	virtual void begin(uint32_t baud);
-	virtual void begin(uint32_t baud, uint32_t format) {
-					  serial3_begin(BAUD2DIV3(baud));
-					  serial3_format(format); }
+	virtual void begin(uint32_t baud, uint32_t format=(uint32_t)-1);
 	virtual void end(void)          { serial3_end(); }
 	virtual void transmitterEnable(uint8_t pin) { serial3_set_transmit_pin(pin); }
 	virtual void setRX(uint8_t pin) { serial3_set_rx(pin); }
@@ -414,10 +405,7 @@ class HardwareSerial4 : public HardwareSerial
 {
 public:
 	constexpr HardwareSerial4(void (* const se)()) : HardwareSerial(se) {}
-	virtual void begin(uint32_t baud);
-	virtual void begin(uint32_t baud, uint32_t format) {
-					  serial4_begin(BAUD2DIV3(baud));
-					  serial4_format(format); }
+	virtual void begin(uint32_t baud, uint32_t format=(uint32_t)-1);
 	virtual void end(void)          { serial4_end(); }
 	virtual void transmitterEnable(uint8_t pin) { serial4_set_transmit_pin(pin); }
 	virtual void setRX(uint8_t pin) { serial4_set_rx(pin); }
@@ -453,10 +441,7 @@ class HardwareSerial5 : public HardwareSerial
 {
 public:
 	constexpr HardwareSerial5(void (* const se)()) : HardwareSerial(se) {}
-	virtual void begin(uint32_t baud);
-	virtual void begin(uint32_t baud, uint32_t format) {
-					  serial5_begin(BAUD2DIV3(baud));
-					  serial5_format(format); }
+	virtual void begin(uint32_t baud, uint32_t format=(uint32_t)-1);
 	virtual void end(void)          { serial5_end(); }
 	virtual void transmitterEnable(uint8_t pin) { serial5_set_transmit_pin(pin); }
 	virtual void setRX(uint8_t pin) { serial5_set_rx(pin); }
@@ -492,17 +477,7 @@ class HardwareSerial6 : public HardwareSerial
 {
 public:
 	constexpr HardwareSerial6(void (* const se)()) : HardwareSerial(se) {}
-#if defined(__MK66FX1M0__)	// For LPUART just pass baud straight in. 
-	virtual void begin(uint32_t baud);
-	virtual void begin(uint32_t baud, uint32_t format) {
-					  serial6_begin(baud);
-					  serial6_format(format); }
-#else
-	virtual void begin(uint32_t baud);
-	virtual void begin(uint32_t baud, uint32_t format) {
-					  serial6_begin(BAUD2DIV3(baud));
-					  serial6_format(format); }
-#endif
+	virtual void begin(uint32_t baud, uint32_t format=(uint32_t)-1);
 	virtual void end(void)          { serial6_end(); }
 	virtual void transmitterEnable(uint8_t pin) { serial6_set_transmit_pin(pin); }
 	virtual void setRX(uint8_t pin) { serial6_set_rx(pin); }
diff --git a/teensy3/HardwareSerial1.cpp b/teensy3/HardwareSerial1.cpp
index fd625ad5..9a13d2d5 100644
--- a/teensy3/HardwareSerial1.cpp
+++ b/teensy3/HardwareSerial1.cpp
@@ -36,8 +36,9 @@ uint8_t _serialEvent1_default __attribute__((weak)) PROGMEM = 0 ;
 
 HardwareSerial Serial1(&serialEvent1);
 
-void HardwareSerial::begin(uint32_t baud) { 
+void HardwareSerial::begin(uint32_t baud, uint32_t format) { 
 	serial_begin(BAUD2DIV(baud)); 
+	if (format != (uint32_t)-1)  serial_format(format);
 	if (!_serialEvent1_default) addToSerialEventsList();
 }
 
diff --git a/teensy3/HardwareSerial2.cpp b/teensy3/HardwareSerial2.cpp
index 8e10cc35..f2738860 100644
--- a/teensy3/HardwareSerial2.cpp
+++ b/teensy3/HardwareSerial2.cpp
@@ -34,7 +34,8 @@ HardwareSerial2 Serial2(&serialEvent2);
 
 uint8_t _serialEvent2_default __attribute__((weak)) PROGMEM = 0 ;
 
-void HardwareSerial2::begin(uint32_t baud) {
+void HardwareSerial2::begin(uint32_t baud, uint32_t format) {
 	serial2_begin(BAUD2DIV2(baud));
+	if (format != (uint32_t)-1)  serial2_format(format);
 	if (!_serialEvent2_default) addToSerialEventsList();
 }
diff --git a/teensy3/HardwareSerial3.cpp b/teensy3/HardwareSerial3.cpp
index 176736aa..722af351 100644
--- a/teensy3/HardwareSerial3.cpp
+++ b/teensy3/HardwareSerial3.cpp
@@ -35,7 +35,8 @@ HardwareSerial3 Serial3(&serialEvent3);
 
 uint8_t _serialEvent3_default __attribute__((weak)) PROGMEM = 0 ;
 
-void HardwareSerial3::begin(uint32_t baud) { 
+void HardwareSerial3::begin(uint32_t baud, uint32_t format) { 
 	serial3_begin(BAUD2DIV3(baud));
+	if (format != (uint32_t)-1)  serial3_format(format);
 	if (!_serialEvent3_default) addToSerialEventsList();
 }
diff --git a/teensy3/HardwareSerial4.cpp b/teensy3/HardwareSerial4.cpp
index b25c87fb..f3884bf8 100644
--- a/teensy3/HardwareSerial4.cpp
+++ b/teensy3/HardwareSerial4.cpp
@@ -37,8 +37,9 @@ HardwareSerial4 Serial4(&serialEvent4);
 
 uint8_t _serialEvent4_default __attribute__((weak)) PROGMEM = 0 ;
 
-void HardwareSerial4::begin(uint32_t baud) { 
+void HardwareSerial4::begin(uint32_t baud, uint32_t format) { 
 	serial4_begin(BAUD2DIV3(baud));
+	if (format != (uint32_t)-1)  serial4_format(format);
 	if (!_serialEvent4_default) addToSerialEventsList();
 }
 
diff --git a/teensy3/HardwareSerial5.cpp b/teensy3/HardwareSerial5.cpp
index 15b7473d..d61aa83d 100644
--- a/teensy3/HardwareSerial5.cpp
+++ b/teensy3/HardwareSerial5.cpp
@@ -37,8 +37,9 @@ HardwareSerial5 Serial5(&serialEvent5);
 
 uint8_t _serialEvent5_default __attribute__((weak)) PROGMEM = 0 ;
 
-void HardwareSerial5::begin(uint32_t baud) { 
+void HardwareSerial5::begin(uint32_t baud, uint32_t format) { 
 	serial5_begin(BAUD2DIV3(baud));
+	if (format != (uint32_t)-1)  serial5_format(format);
 	if (!_serialEvent5_default) addToSerialEventsList();
 }
 
diff --git a/teensy3/HardwareSerial6.cpp b/teensy3/HardwareSerial6.cpp
index 3d80baf7..5364c3ba 100644
--- a/teensy3/HardwareSerial6.cpp
+++ b/teensy3/HardwareSerial6.cpp
@@ -37,12 +37,13 @@ HardwareSerial6 Serial6(&serialEvent6);
 
 uint8_t _serialEvent6_default __attribute__((weak)) PROGMEM = 0 ;
 
-void HardwareSerial6::begin(uint32_t baud) { 	
+void HardwareSerial6::begin(uint32_t baud, uint32_t format) { 	
 #if defined(__MK66FX1M0__)	// For LPUART just pass baud straight in. 
 	serial6_begin(baud);
 #else
 	serial6_begin(BAUD2DIV3(baud));
 #endif	
+	if (format != (uint32_t)-1)  serial6_format(format);
 	if (!_serialEvent6_default) addToSerialEventsList();
 }
 
diff --git a/teensy3/core_cmInstr.h b/teensy3/core_cmInstr.h
index 971ae7e9..bfdfcacd 100644
--- a/teensy3/core_cmInstr.h
+++ b/teensy3/core_cmInstr.h
@@ -316,7 +316,7 @@ __attribute__( ( always_inline ) ) __STATIC_INLINE void __CLREX(void)
  */
 #define __SSAT(ARG1,ARG2) \
 ({                          \
-  uint32_t __RES, __ARG1 = (ARG1); \
+  int32_t __RES, __ARG1 = (ARG1); \
   __ASM ("ssat %0, %1, %2" : "=r" (__RES) :  "I" (ARG2), "r" (__ARG1) ); \
   __RES; \
  })
diff --git a/teensy4/FS.h b/teensy4/FS.h
index be15d5af..8321c477 100644
--- a/teensy4/FS.h
+++ b/teensy4/FS.h
@@ -273,6 +273,7 @@ class FS
 {
 public:
 	FS() {}
+	virtual ~FS() {}
 	virtual File open(const char *filename, uint8_t mode = FILE_READ) = 0;
 	virtual bool exists(const char *filepath) = 0;
 	virtual bool mkdir(const char *filepath) = 0;
diff --git a/teensy4/HardwareSerial.cpp b/teensy4/HardwareSerial.cpp
index 43007d83..4b933b7f 100644
--- a/teensy4/HardwareSerial.cpp
+++ b/teensy4/HardwareSerial.cpp
@@ -244,11 +244,13 @@ void HardwareSerialIMXRT::begin(uint32_t baud, uint16_t format)
 
 inline void HardwareSerialIMXRT::rts_assert()
 {
-	DIRECT_WRITE_LOW(rts_pin_baseReg_, rts_pin_bitmask_);
+	if (rts_pin_invert_) DIRECT_WRITE_HIGH(rts_pin_baseReg_, rts_pin_bitmask_);
+	else DIRECT_WRITE_LOW(rts_pin_baseReg_, rts_pin_bitmask_);
 }
 
 inline void HardwareSerialIMXRT::rts_deassert()
 {
+	if (rts_pin_invert_) DIRECT_WRITE_LOW(rts_pin_baseReg_, rts_pin_bitmask_);
 	DIRECT_WRITE_HIGH(rts_pin_baseReg_, rts_pin_bitmask_);
 }
 
@@ -318,7 +320,7 @@ void HardwareSerialIMXRT::setRX(uint8_t pin)
 				//  configure the pin. 
 				*(portControlRegister(pin)) = IOMUXC_PAD_DSE(7) | IOMUXC_PAD_PKE | IOMUXC_PAD_PUE | IOMUXC_PAD_PUS(3) | IOMUXC_PAD_HYS;;
 				*(portConfigRegister(pin)) = pin_to_xbar_info[i].mux_val;
-				port->MODIR |= LPUART_MODIR_TXCTSE;
+
 				if (pin_to_xbar_info[i].select_input_register) *(pin_to_xbar_info[i].select_input_register) = pin_to_xbar_info[i].select_val;
 				//Serial.printf("SerialX::begin stat:%x ctrl:%x fifo:%x water:%x\n", port->STAT, port->CTRL, port->FIFO, port->WATER );
 				//Serial.printf("  PINCFG: %x MODIR: %x\n", port->PINCFG, port->MODIR);	
@@ -365,6 +367,23 @@ bool HardwareSerialIMXRT::attachRts(uint8_t pin)
 	if (pin < CORE_NUM_DIGITAL) {
 		rts_pin_baseReg_ = PIN_TO_BASEREG(pin);
 		rts_pin_bitmask_ = PIN_TO_BITMASK(pin);
+		rts_pin_invert_ = false;
+		pinMode(pin, OUTPUT);
+		rts_assert();
+	} else {
+		rts_pin_baseReg_ = NULL;
+		return 0;
+	}
+	return 1;
+}
+
+bool HardwareSerialIMXRT::attachRtsInverted(uint8_t pin)
+{
+	if (!(hardware->ccm_register & hardware->ccm_value)) return 0;
+	if (pin < CORE_NUM_DIGITAL) {
+		rts_pin_baseReg_ = PIN_TO_BASEREG(pin);
+		rts_pin_bitmask_ = PIN_TO_BITMASK(pin);
+		rts_pin_invert_ = true;
 		pinMode(pin, OUTPUT);
 		rts_assert();
 	} else {
@@ -717,7 +736,7 @@ void HardwareSerialIMXRT::addToSerialEventsList() {
 }
 
 
-const pin_to_xbar_info_t PROGMEM pin_to_xbar_info[] = {
+extern const pin_to_xbar_info_t PROGMEM pin_to_xbar_info[] __attribute__((weak)) = {
 	{0,  17, 1, &IOMUXC_XBAR1_IN17_SELECT_INPUT, 0x1},
 	{1,  16, 1, nullptr, 0},
 	{2,   6, 3, &IOMUXC_XBAR1_IN06_SELECT_INPUT, 0x0},
@@ -757,5 +776,5 @@ const pin_to_xbar_info_t PROGMEM pin_to_xbar_info[] = {
 #endif
 };
 
-const uint8_t PROGMEM count_pin_to_xbar_info = sizeof(pin_to_xbar_info)/sizeof(pin_to_xbar_info[0]);
+extern const uint8_t PROGMEM count_pin_to_xbar_info __attribute__((weak)) = sizeof(pin_to_xbar_info)/sizeof(pin_to_xbar_info[0]);
 
diff --git a/teensy4/HardwareSerial.h b/teensy4/HardwareSerial.h
index f585bfcd..9a29409a 100644
--- a/teensy4/HardwareSerial.h
+++ b/teensy4/HardwareSerial.h
@@ -182,20 +182,25 @@ class HardwareSerialIMXRT : public HardwareSerial
 	} pin_info_t;
 
 	typedef struct {
+		// General settings for this Serial object.
 		uint8_t serial_index;	// which object are we? 0 based
-		IRQ_NUMBER_t irq;
 		void (*irq_handler)(void);
 		void (* _serialEvent)(void);
+		const uint16_t irq_priority;
+		const uint16_t rts_low_watermark;
+		const uint16_t rts_high_watermark;
+
+		// Settings that apply to underlying LPUART object.
+		IRQ_NUMBER_t irq;
 		volatile uint32_t &ccm_register;
 		const uint32_t ccm_value;
+		const uint8_t xbar_out_lpuartX_trig_input;
+
+		// Pin lists
 		pin_info_t rx_pins[cnt_rx_pins];
 		pin_info_t tx_pins[cnt_tx_pins];
 		const uint8_t cts_pin;
 		const uint8_t cts_mux_val;
-		const uint16_t irq_priority;
-		const uint16_t rts_low_watermark;
-		const uint16_t rts_high_watermark;
-		const uint8_t xbar_out_lpuartX_trig_input;
 	} hardware_t;
 public:
 	constexpr HardwareSerialIMXRT(uintptr_t myport, const hardware_t *myhardware,
@@ -240,7 +245,12 @@ class HardwareSerialIMXRT : public HardwareSerial
 	// receive more data, or HIGH when the serial device should pause transmission.
 	// All digital pins are supported.
 	bool attachRts(uint8_t pin);
-	// Configure CTS flow control.  Teensy will transmit when this pin is LOw
+	// Same as attachRts except the signal levels are reversed.
+	// Configure RTS flow control.  The pin will be HIGH when Teensy is able to
+	// receive more data, or LOW when the serial device should pause transmission.
+	// All digital pins are supported.
+	bool attachRtsInverted(uint8_t pin);
+	// Configure CTS flow control.  Teensy will transmit when this pin is LOW
 	// and will pause transmission when the pin is HIGH.  Only specific pins are
 	// supported.  See https://www.pjrc.com/teensy/td_uart.html
 	bool attachCts(uint8_t pin);
@@ -327,6 +337,7 @@ class HardwareSerialIMXRT : public HardwareSerial
 
 	volatile uint32_t 	*rts_pin_baseReg_ = 0;
 	uint32_t 			rts_pin_bitmask_ = 0;
+	bool				rts_pin_invert_ = false;
 
   	inline void rts_assert();
   	inline void rts_deassert();
diff --git a/teensy4/HardwareSerial1.cpp b/teensy4/HardwareSerial1.cpp
index 549e2245..ea247d8a 100644
--- a/teensy4/HardwareSerial1.cpp
+++ b/teensy4/HardwareSerial1.cpp
@@ -45,28 +45,35 @@ void IRQHandler_Serial1()
 	Serial1.IRQHandler();
 }
 
+// Should we allow each one to be overwritten or all of a Port...
+#ifndef SERIAL1_RX_PINS 
+#define SERIAL1_UART_ADDR IMXRT_LPUART6_ADDRESS
+#define SERIAL1_LPUART IRQ_LPUART6, CCM_CCGR3, CCM_CCGR3_LPUART6(CCM_CCGR_ON),	XBARA1_OUT_LPUART6_TRG_INPUT
+#define SERIAL1_CTS_PIN 0xff, 0 
+#if defined(ARDUINO_TEENSY41)
+#define SERIAL1_RX_PINS {{0,2, &IOMUXC_LPUART6_RX_SELECT_INPUT, 1}, {52, 2, &IOMUXC_LPUART6_RX_SELECT_INPUT, 0}}
+#define SERIAL1_TX_PINS {{1,2, &IOMUXC_LPUART6_TX_SELECT_INPUT, 1}, {53, 2, &IOMUXC_LPUART6_TX_SELECT_INPUT, 0}}
+#else
+#define SERIAL1_RX_PINS {{0,2, &IOMUXC_LPUART6_RX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}}
+#define SERIAL1_TX_PINS {{1,2, &IOMUXC_LPUART6_TX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}}
+#endif
+#endif
+
+
 
 // Serial1
 static BUFTYPE tx_buffer1[SERIAL1_TX_BUFFER_SIZE];
 static BUFTYPE rx_buffer1[SERIAL1_RX_BUFFER_SIZE];
 
-const HardwareSerialIMXRT::hardware_t UART6_Hardware = {
-	0, IRQ_LPUART6, &IRQHandler_Serial1, 
+const HardwareSerialIMXRT::hardware_t Serial1_Hardware = {
+	0, 
+	&IRQHandler_Serial1, 
 	&serialEvent1,
-	CCM_CCGR3, CCM_CCGR3_LPUART6(CCM_CCGR_ON),
-	#if defined(ARDUINO_TEENSY41)
-	{{0,2, &IOMUXC_LPUART6_RX_SELECT_INPUT, 1}, {52, 2, &IOMUXC_LPUART6_RX_SELECT_INPUT, 0}},
-	{{1,2, &IOMUXC_LPUART6_TX_SELECT_INPUT, 1}, {53, 2, &IOMUXC_LPUART6_TX_SELECT_INPUT, 0}},
-	#else
-	{{0,2, &IOMUXC_LPUART6_RX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}},
-	{{1,2, &IOMUXC_LPUART6_TX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}},
-	#endif
-	0xff, // No CTS pin
-	0, // No CTS
 	IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-	XBARA1_OUT_LPUART6_TRG_INPUT	// XBar Tigger 
+	// Stuff that can be overwritten easily by variant
+	SERIAL1_LPUART, SERIAL1_RX_PINS, SERIAL1_TX_PINS, SERIAL1_CTS_PIN
 };
-HardwareSerialIMXRT Serial1(IMXRT_LPUART6_ADDRESS, &UART6_Hardware, tx_buffer1,
+HardwareSerialIMXRT Serial1(SERIAL1_UART_ADDR, &Serial1_Hardware, tx_buffer1,
 	SERIAL1_TX_BUFFER_SIZE, rx_buffer1, SERIAL1_RX_BUFFER_SIZE);
 
 //void serialEvent1() __attribute__((weak));
diff --git a/teensy4/HardwareSerial2.cpp b/teensy4/HardwareSerial2.cpp
index 049091b8..51d38eb7 100644
--- a/teensy4/HardwareSerial2.cpp
+++ b/teensy4/HardwareSerial2.cpp
@@ -45,38 +45,34 @@ void IRQHandler_Serial2()
 	Serial2.IRQHandler();
 }
 
+#ifndef SERIAL2_RX_PINS 
+#define SERIAL2_CTS_PIN 0xff, 0 
+#if !defined(ARDUINO_TEENSY_MICROMOD)
+#define SERIAL2_UART_ADDR IMXRT_LPUART4_ADDRESS
+#define SERIAL2_LPUART	IRQ_LPUART4, CCM_CCGR1, CCM_CCGR1_LPUART4(CCM_CCGR_ON), XBARA1_OUT_LPUART4_TRG_INPUT
+#define SERIAL2_RX_PINS	{{7,2, &IOMUXC_LPUART4_RX_SELECT_INPUT, 2}, {0xff, 0xff, nullptr, 0}}
+#define SERIAL2_TX_PINS	{{8,2, &IOMUXC_LPUART4_TX_SELECT_INPUT, 2}, {0xff, 0xff, nullptr, 0}}
+
+#else
+#define SERIAL2_UART_ADDR IMXRT_LPUART3_ADDRESS
+#define SERIAL2_LPUART   IRQ_LPUART3, CCM_CCGR0, CCM_CCGR0_LPUART3(CCM_CCGR_ON), XBARA1_OUT_LPUART3_TRG_INPUT
+#define SERIAL2_RX_PINS  {{16,2, &IOMUXC_LPUART3_RX_SELECT_INPUT, 0}, {0xff, 0xff, nullptr, 0}}
+#define SERIAL2_TX_PINS  {{17,2, &IOMUXC_LPUART3_TX_SELECT_INPUT, 0}, {0xff, 0xff, nullptr, 0}}
+#endif
+#endif
+
 
 // Serial2
 static BUFTYPE tx_buffer2[SERIAL2_TX_BUFFER_SIZE];
 static BUFTYPE rx_buffer2[SERIAL2_RX_BUFFER_SIZE];
 
-#ifndef ARDUINO_TEENSY_MICROMOD
-static HardwareSerialIMXRT::hardware_t UART4_Hardware = {
-	1, IRQ_LPUART4, &IRQHandler_Serial2, 
+static HardwareSerialIMXRT::hardware_t Serial2_Hardware = {
+	1, 
+	&IRQHandler_Serial2, 
 	&serialEvent2,
-	CCM_CCGR1, CCM_CCGR1_LPUART4(CCM_CCGR_ON),
-	{{7,2, &IOMUXC_LPUART4_RX_SELECT_INPUT, 2}, {0xff, 0xff, nullptr, 0}},
-	{{8,2, &IOMUXC_LPUART4_TX_SELECT_INPUT, 2}, {0xff, 0xff, nullptr, 0}},
-	0xff, // No CTS pin
-	0, // No CTS
 	IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-	XBARA1_OUT_LPUART4_TRG_INPUT
+	// Stuff that can be overwritten easily by variant
+	SERIAL2_LPUART, SERIAL2_RX_PINS, SERIAL2_TX_PINS, SERIAL2_CTS_PIN
 };
-HardwareSerialIMXRT Serial2(IMXRT_LPUART4_ADDRESS, &UART4_Hardware, tx_buffer2,
+HardwareSerialIMXRT Serial2(SERIAL2_UART_ADDR, &Serial2_Hardware, tx_buffer2,
 	SERIAL2_TX_BUFFER_SIZE, rx_buffer2, SERIAL2_RX_BUFFER_SIZE);
-
-#else  // Teensy Micromod
-static HardwareSerialIMXRT::hardware_t UART3_Hardware = {
-    3, IRQ_LPUART3, &IRQHandler_Serial2, 
-    &serialEvent2,
-    CCM_CCGR0, CCM_CCGR0_LPUART3(CCM_CCGR_ON),
-    {{16,2, &IOMUXC_LPUART3_RX_SELECT_INPUT, 0}, {0xff, 0xff, nullptr, 0}},
-    {{17,2, &IOMUXC_LPUART3_TX_SELECT_INPUT, 0}, {0xff, 0xff, nullptr, 0}},
-    0xff, // No CTS pin
-    0, // No CTS
-    IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-    XBARA1_OUT_LPUART3_TRG_INPUT
-};
-HardwareSerialIMXRT Serial2(IMXRT_LPUART3_ADDRESS, &UART3_Hardware, tx_buffer2,
-	 SERIAL2_TX_BUFFER_SIZE, rx_buffer2, SERIAL2_RX_BUFFER_SIZE);
-#endif
diff --git a/teensy4/HardwareSerial3.cpp b/teensy4/HardwareSerial3.cpp
index 3c99725b..ab57a47a 100644
--- a/teensy4/HardwareSerial3.cpp
+++ b/teensy4/HardwareSerial3.cpp
@@ -44,21 +44,29 @@ void IRQHandler_Serial3()
 	Serial3.IRQHandler();
 }
 
+#ifndef SERIAL3_RX_PINS 
+#define SERIAL3_UART_ADDR IMXRT_LPUART2_ADDRESS
+#define SERIAL3_LPUART IRQ_LPUART2, CCM_CCGR0, CCM_CCGR0_LPUART2(CCM_CCGR_ON), XBARA1_OUT_LPUART2_TRG_INPUT
+#define SERIAL3_CTS_PIN 19, 2 
+#define SERIAL3_RX_PINS {{15,2, &IOMUXC_LPUART2_RX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}}
+#define SERIAL3_TX_PINS {{14,2, &IOMUXC_LPUART2_TX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}}
+#endif
+
+
+
+
 // Serial3
 static BUFTYPE tx_buffer3[SERIAL3_TX_BUFFER_SIZE];
 static BUFTYPE rx_buffer3[SERIAL3_RX_BUFFER_SIZE];
 
-static HardwareSerialIMXRT::hardware_t UART2_Hardware = {
-	2, IRQ_LPUART2, &IRQHandler_Serial3, 
+const HardwareSerialIMXRT::hardware_t SERIAL3_Hardware = {
+	2, 
+	&IRQHandler_Serial3, 
 	&serialEvent3,
-	CCM_CCGR0, CCM_CCGR0_LPUART2(CCM_CCGR_ON), 
-	{{15,2, &IOMUXC_LPUART2_RX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}},
-	{{14,2, &IOMUXC_LPUART2_TX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}},
-	19, //IOMUXC_SW_MUX_CTL_PAD_GPIO_AD_B1_00, // 19
-	2, // page 473 
 	IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-	XBARA1_OUT_LPUART2_TRG_INPUT
+	// Stuff that can be overwritten easily by variant
+	SERIAL3_LPUART, SERIAL3_RX_PINS, SERIAL3_TX_PINS, SERIAL3_CTS_PIN
 };
-HardwareSerialIMXRT Serial3(IMXRT_LPUART2_ADDRESS, &UART2_Hardware, tx_buffer3,
+HardwareSerialIMXRT Serial3(SERIAL3_UART_ADDR, &SERIAL3_Hardware, tx_buffer3,
 	SERIAL3_TX_BUFFER_SIZE, rx_buffer3, SERIAL3_RX_BUFFER_SIZE);
 
diff --git a/teensy4/HardwareSerial4.cpp b/teensy4/HardwareSerial4.cpp
index cf92808c..f3eb300c 100644
--- a/teensy4/HardwareSerial4.cpp
+++ b/teensy4/HardwareSerial4.cpp
@@ -46,36 +46,34 @@ void IRQHandler_Serial4()
 }
 
 // Serial4
+
+#ifndef SERIAL4_RX_PINS 
+#define SERIAL4_CTS_PIN 0xff, 0 
+#if !defined(ARDUINO_TEENSY_MICROMOD)
+#define SERIAL4_UART_ADDR IMXRT_LPUART3_ADDRESS
+#define SERIAL4_LPUART   IRQ_LPUART3, CCM_CCGR0, CCM_CCGR0_LPUART3(CCM_CCGR_ON), XBARA1_OUT_LPUART3_TRG_INPUT
+#define SERIAL4_RX_PINS  {{16,2, &IOMUXC_LPUART3_RX_SELECT_INPUT, 0}, {0xff, 0xff, nullptr, 0}}
+#define SERIAL4_TX_PINS  {{17,2, &IOMUXC_LPUART3_TX_SELECT_INPUT, 0}, {0xff, 0xff, nullptr, 0}}
+
+#else
+#define SERIAL4_UART_ADDR IMXRT_LPUART4_ADDRESS
+#define SERIAL4_LPUART	IRQ_LPUART4, CCM_CCGR1, CCM_CCGR1_LPUART4(CCM_CCGR_ON), XBARA1_OUT_LPUART4_TRG_INPUT
+#define SERIAL4_RX_PINS	{{7,2, &IOMUXC_LPUART4_RX_SELECT_INPUT, 2}, {0xff, 0xff, nullptr, 0}}
+#define SERIAL4_TX_PINS	{{8,2, &IOMUXC_LPUART4_TX_SELECT_INPUT, 2}, {0xff, 0xff, nullptr, 0}}
+#endif
+#endif
+
 static BUFTYPE tx_buffer4[SERIAL4_TX_BUFFER_SIZE];
 static BUFTYPE rx_buffer4[SERIAL4_RX_BUFFER_SIZE];
 
-#ifndef ARDUINO_TEENSY_MICROMOD
-static HardwareSerialIMXRT::hardware_t UART3_Hardware = {
-	3, IRQ_LPUART3, &IRQHandler_Serial4, 
+static HardwareSerialIMXRT::hardware_t SERIAL4_Hardware = {
+	3, 
+	&IRQHandler_Serial4, 
 	&serialEvent4,
-	CCM_CCGR0, CCM_CCGR0_LPUART3(CCM_CCGR_ON),
-	{{16,2, &IOMUXC_LPUART3_RX_SELECT_INPUT, 0}, {0xff, 0xff, nullptr, 0}},
-	{{17,2, &IOMUXC_LPUART3_TX_SELECT_INPUT, 0}, {0xff, 0xff, nullptr, 0}},
-	0xff, // No CTS pin
-	0, // No CTS
 	IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-	XBARA1_OUT_LPUART3_TRG_INPUT
+	// Stuff that can be overwritten easily by variant
+	SERIAL4_LPUART, SERIAL4_RX_PINS, SERIAL4_TX_PINS, SERIAL4_CTS_PIN
 };
-HardwareSerialIMXRT Serial4(IMXRT_LPUART3_ADDRESS, &UART3_Hardware, tx_buffer4,
+HardwareSerialIMXRT Serial4(SERIAL4_UART_ADDR, &SERIAL4_Hardware, tx_buffer4,
 	SERIAL4_TX_BUFFER_SIZE, rx_buffer4, SERIAL4_RX_BUFFER_SIZE);
 
-#else
-static HardwareSerialIMXRT::hardware_t UART4_Hardware = {
-    1, IRQ_LPUART4, &IRQHandler_Serial4, 
-    &serialEvent4, /*&_serialEvent4_default,*/
-    CCM_CCGR1, CCM_CCGR1_LPUART4(CCM_CCGR_ON),
-    {{7,2, &IOMUXC_LPUART4_RX_SELECT_INPUT, 2}, {0xff, 0xff, nullptr, 0}},
-    {{8,2, &IOMUXC_LPUART4_TX_SELECT_INPUT, 2}, {0xff, 0xff, nullptr, 0}},
-    0xff, // No CTS pin
-    0, // No CTS
-    IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-    XBARA1_OUT_LPUART4_TRG_INPUT
-};
-HardwareSerialIMXRT Serial4(IMXRT_LPUART4_ADDRESS, &UART4_Hardware, tx_buffer4,
-	 SERIAL4_TX_BUFFER_SIZE, rx_buffer4, SERIAL4_RX_BUFFER_SIZE);
-#endif
diff --git a/teensy4/HardwareSerial5.cpp b/teensy4/HardwareSerial5.cpp
index fce9672d..c980999f 100644
--- a/teensy4/HardwareSerial5.cpp
+++ b/teensy4/HardwareSerial5.cpp
@@ -44,32 +44,40 @@ void IRQHandler_Serial5()
 {
 	Serial5.IRQHandler();
 }
+
+#ifndef SERIAL5_RX_PINS 
+#define SERIAL5_UART_ADDR IMXRT_LPUART8_ADDRESS
+#define SERIAL5_LPUART IRQ_LPUART8, CCM_CCGR6, CCM_CCGR6_LPUART8(CCM_CCGR_ON),	XBARA1_OUT_LPUART8_TRG_INPUT
+
+#if defined(ARDUINO_TEENSY41)
+#define SERIAL5_RX_PINS {{21,2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 1}, {46, 2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 0}}
+#define SERIAL5_TX_PINS {{20,2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 1}, {47, 2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 0}}
+#define SERIAL5_CTS_PIN 43, 2 
+
+#elif defined(ARDUINO_TEENSY40)
+#define SERIAL5_RX_PINS {{21,2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 1}, {38, 2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 0}}
+#define SERIAL5_TX_PINS {{20,2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 1}, {39, 2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 0}}
+#define SERIAL5_CTS_PIN 35, 2 
+
+#else // ARDUINO_TEENSY_MICROMOD
+#define SERIAL5_RX_PINS {{21,2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 1}, {39, 2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 0}}
+#define SERIAL5_TX_PINS {{20,2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 1}, {38, 2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 0}}
+#define SERIAL5_CTS_PIN 35, 2 
+#endif
+
+#endif
+
+
 // Serial5
 static BUFTYPE tx_buffer5[SERIAL5_TX_BUFFER_SIZE];
 static BUFTYPE rx_buffer5[SERIAL5_RX_BUFFER_SIZE];
 
-static HardwareSerialIMXRT::hardware_t UART8_Hardware = {
-	4, IRQ_LPUART8, &IRQHandler_Serial5, 
+static HardwareSerialIMXRT::hardware_t Serial5_Hardware = {
+	4, 
+	&IRQHandler_Serial5, 
 	&serialEvent5,
-	CCM_CCGR6, CCM_CCGR6_LPUART8(CCM_CCGR_ON),
-	#if defined(ARDUINO_TEENSY41)
-	{{21,2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 1}, {46, 2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 0}},
-	{{20,2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 1}, {47, 2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 0}},
-	43, //  CTS pin
-	2, //  CTS
-	#elif defined(ARDUINO_TEENSY40)
-	{{21,2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 1}, {38, 2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 0}},
-	{{20,2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 1}, {39, 2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 0}},
-	35, //  CTS pin
-	2, //  CTS
-	#else // ARDUINO_TEENSY_MICROMOD
-	{{21,2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 1}, {39, 2, &IOMUXC_LPUART8_RX_SELECT_INPUT, 0}},
-	{{20,2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 1}, {38, 2, &IOMUXC_LPUART8_TX_SELECT_INPUT, 0}},
-	35, //  CTS pin
-	2, //  CTS
-	#endif
 	IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-	XBARA1_OUT_LPUART8_TRG_INPUT
+	SERIAL5_LPUART, SERIAL5_RX_PINS, SERIAL5_TX_PINS, SERIAL5_CTS_PIN
 };
-HardwareSerialIMXRT Serial5(IMXRT_LPUART8_ADDRESS, &UART8_Hardware, tx_buffer5,
+HardwareSerialIMXRT Serial5(SERIAL5_UART_ADDR, &Serial5_Hardware, tx_buffer5,
 	SERIAL5_TX_BUFFER_SIZE, rx_buffer5, SERIAL5_RX_BUFFER_SIZE);
diff --git a/teensy4/HardwareSerial6.cpp b/teensy4/HardwareSerial6.cpp
index 2ea31543..54ffb3d6 100644
--- a/teensy4/HardwareSerial6.cpp
+++ b/teensy4/HardwareSerial6.cpp
@@ -44,22 +44,26 @@ void IRQHandler_Serial6()
 	Serial6.IRQHandler();
 }
 
+#ifndef SERIAL6_RX_PINS 
+#define SERIAL6_UART_ADDR IMXRT_LPUART1_ADDRESS
+#define SERIAL6_LPUART	IRQ_LPUART1, CCM_CCGR5, CCM_CCGR5_LPUART1(CCM_CCGR_ON), XBARA1_OUT_LPUART1_TRG_INPUT 
+#define SERIAL6_CTS_PIN 0xff, 0 
+#define SERIAL6_RX_PINS {{25,2, nullptr, 0}, {0xff, 0xff, nullptr, 0}}
+#define SERIAL6_TX_PINS {{24,2, nullptr, 0}, {0xff, 0xff, nullptr, 0}}
+#endif
+
 
 // Serial6
 static BUFTYPE tx_buffer6[SERIAL6_TX_BUFFER_SIZE];
 static BUFTYPE rx_buffer6[SERIAL6_RX_BUFFER_SIZE];
 
-static HardwareSerialIMXRT::hardware_t UART1_Hardware = {
-	5, IRQ_LPUART1, &IRQHandler_Serial6, 
+static HardwareSerialIMXRT::hardware_t Serial6_Hardware = {
+	5, 
+	&IRQHandler_Serial6, 
 	&serialEvent6,
-	CCM_CCGR5, CCM_CCGR5_LPUART1(CCM_CCGR_ON),
-	{{25,2, nullptr, 0}, {0xff, 0xff, nullptr, 0}},
-	{{24,2, nullptr, 0}, {0xff, 0xff, nullptr, 0}},
-	0xff, // No CTS pin
-	0, // No CTS
 	IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-	XBARA1_OUT_LPUART1_TRG_INPUT
+	SERIAL6_LPUART, SERIAL6_RX_PINS, SERIAL6_TX_PINS, SERIAL6_CTS_PIN
 };
 
-HardwareSerialIMXRT Serial6(IMXRT_LPUART1_ADDRESS, &UART1_Hardware, tx_buffer6,
+HardwareSerialIMXRT Serial6(SERIAL6_UART_ADDR, &Serial6_Hardware, tx_buffer6,
 	SERIAL6_TX_BUFFER_SIZE, rx_buffer6, SERIAL6_RX_BUFFER_SIZE);
diff --git a/teensy4/HardwareSerial7.cpp b/teensy4/HardwareSerial7.cpp
index d0b7b4b1..08fefa4f 100644
--- a/teensy4/HardwareSerial7.cpp
+++ b/teensy4/HardwareSerial7.cpp
@@ -48,16 +48,20 @@ void IRQHandler_Serial7()
 static BUFTYPE tx_buffer7[SERIAL7_TX_BUFFER_SIZE];
 static BUFTYPE rx_buffer7[SERIAL7_RX_BUFFER_SIZE];
 
-static HardwareSerialIMXRT::hardware_t UART7_Hardware = {
-	6, IRQ_LPUART7, &IRQHandler_Serial7, 
+#ifndef SERIAL7_RX_PINS 
+#define SERIAL7_UART_ADDR IMXRT_LPUART7_ADDRESS
+#define SERIAL7_LPUART IRQ_LPUART7, CCM_CCGR5, CCM_CCGR5_LPUART7(CCM_CCGR_ON), XBARA1_OUT_LPUART7_TRG_INPUT
+#define SERIAL7_CTS_PIN 0xff, 0 
+#define SERIAL7_RX_PINS {{28,2, &IOMUXC_LPUART7_RX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}}
+#define SERIAL7_TX_PINS {{29,2, &IOMUXC_LPUART7_TX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}}
+#endif
+
+static HardwareSerialIMXRT::hardware_t Serial7_Hardware = {
+	6, 
+	&IRQHandler_Serial7, 
 	&serialEvent7,
-	CCM_CCGR5, CCM_CCGR5_LPUART7(CCM_CCGR_ON),
-	{{28,2, &IOMUXC_LPUART7_RX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}},
-	{{29,2, &IOMUXC_LPUART7_TX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}},
-	0xff, // No CTS pin
-	0, // No CTS
 	IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-	XBARA1_OUT_LPUART7_TRG_INPUT
+	SERIAL7_LPUART, SERIAL7_RX_PINS, SERIAL7_TX_PINS, SERIAL7_CTS_PIN
 };
-HardwareSerialIMXRT Serial7(IMXRT_LPUART7_ADDRESS, &UART7_Hardware, tx_buffer7,
+HardwareSerialIMXRT Serial7(SERIAL7_UART_ADDR, &Serial7_Hardware, tx_buffer7,
 	SERIAL7_TX_BUFFER_SIZE, rx_buffer7, SERIAL7_RX_BUFFER_SIZE);
diff --git a/teensy4/HardwareSerial8.cpp b/teensy4/HardwareSerial8.cpp
index 24883dc2..9c430cdd 100644
--- a/teensy4/HardwareSerial8.cpp
+++ b/teensy4/HardwareSerial8.cpp
@@ -30,7 +30,7 @@
 
 #include <Arduino.h>
 #include "HardwareSerial.h"
-#if defined(__IMXRT1062__) && defined(ARDUINO_TEENSY41)
+#if defined(__IMXRT1062__) && (defined(ARDUINO_TEENSY41) || defined(SERIAL8_RX_PINS))
 
 #ifndef SERIAL8_TX_BUFFER_SIZE
 #define SERIAL8_TX_BUFFER_SIZE     40 // number of outgoing bytes to buffer
@@ -45,22 +45,27 @@ void IRQHandler_Serial8()
 	Serial8.IRQHandler();
 }
 
+#ifndef SERIAL8_RX_PINS 
+#define SERIAL8_UART_ADDR IMXRT_LPUART5_ADDRESS
+#define SERIAL8_LPUART IRQ_LPUART5, CCM_CCGR3, CCM_CCGR3_LPUART5(CCM_CCGR_ON), XBARA1_OUT_LPUART5_TRG_INPUT
+#define SERIAL8_CTS_PIN 50, 2 
+#define SERIAL8_RX_PINS {{34,1, &IOMUXC_LPUART5_RX_SELECT_INPUT, 1}, {48, 2, &IOMUXC_LPUART5_RX_SELECT_INPUT, 0}}
+#define SERIAL8_TX_PINS {{35,1, &IOMUXC_LPUART5_TX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}}
+#endif
+
 
 // Serial8
 static BUFTYPE tx_buffer8[SERIAL8_TX_BUFFER_SIZE];
 static BUFTYPE rx_buffer8[SERIAL8_RX_BUFFER_SIZE];
 
-static HardwareSerialIMXRT::hardware_t UART5_Hardware = {
-	7, IRQ_LPUART5, &IRQHandler_Serial8, 
+static HardwareSerialIMXRT::hardware_t Serial8_Hardware = {
+	7, 
+	&IRQHandler_Serial8, 
 	&serialEvent8,
-	CCM_CCGR3, CCM_CCGR3_LPUART5(CCM_CCGR_ON),
-	{{34,1, &IOMUXC_LPUART5_RX_SELECT_INPUT, 1}, {48, 2, &IOMUXC_LPUART5_RX_SELECT_INPUT, 0}},
-	{{35,1, &IOMUXC_LPUART5_TX_SELECT_INPUT, 1}, {0xff, 0xff, nullptr, 0}},
-	50, // CTS pin
-	2, //  CTS
 	IRQ_PRIORITY, 38, 24, // IRQ, rts_low_watermark, rts_high_watermark
-	XBARA1_OUT_LPUART5_TRG_INPUT
+	SERIAL8_LPUART, SERIAL8_RX_PINS, SERIAL8_TX_PINS, SERIAL8_CTS_PIN
 };
-HardwareSerialIMXRT Serial8(IMXRT_LPUART5_ADDRESS, &UART5_Hardware, tx_buffer8,
+HardwareSerialIMXRT Serial8(IMXRT_LPUART5_ADDRESS, &Serial8_Hardware, tx_buffer8,
 	SERIAL8_TX_BUFFER_SIZE, rx_buffer8, SERIAL8_RX_BUFFER_SIZE);
 #endif
+
diff --git a/teensy4/Time.cpp b/teensy4/Time.cpp
index 13c097e6..bc8fc90e 100644
--- a/teensy4/Time.cpp
+++ b/teensy4/Time.cpp
@@ -103,16 +103,17 @@ uint32_t makeTime(const DateTimeFields &tm)
   uint32_t seconds;
 
   // seconds from 1970 till 1 jan 00:00:00 of the given year
-  seconds = (tm.year - 70) * (SECS_PER_DAY * 365);
-  for (i = 70; i < tm.year; i++) {
-    if (LEAP_YEAR(i - 70)) {
+  int year = tm.year - 70;
+  seconds = year * (SECS_PER_DAY * 365);
+  for (i = 0; i < year; i++) {
+    if (LEAP_YEAR(i)) {
       seconds += SECS_PER_DAY;   // add extra days for leap years
     }
   }
 
   // add days for this year, months start from 1
   for (i = 0; i < tm.mon; i++) {
-    if ( (i == 1) && LEAP_YEAR(tm.year)) {
+    if ( (i == 1) && LEAP_YEAR(year)) {
       seconds += SECS_PER_DAY * 29;
     } else {
       seconds += SECS_PER_DAY * monthDays[i];
diff --git a/teensy4/analog.c b/teensy4/analog.c
index f9110b59..65f9cefe 100644
--- a/teensy4/analog.c
+++ b/teensy4/analog.c
@@ -8,7 +8,7 @@ static uint8_t analog_config_bits = 10;
 static uint8_t analog_num_average = 4;
 
 
-const uint8_t pin_to_channel[] = { // pg 482
+const uint8_t pin_to_channel[] __attribute__((weak)) = { // pg 482
 	7,	// 0/A0  AD_B1_02
 	8,	// 1/A1  AD_B1_03
 	12,	// 2/A2  AD_B1_07
diff --git a/teensy4/clockspeed.c b/teensy4/clockspeed.c
index be2e1acb..323e974e 100644
--- a/teensy4/clockspeed.c
+++ b/teensy4/clockspeed.c
@@ -16,6 +16,8 @@ volatile uint32_t F_BUS_ACTUAL = 132000000;
 #define OVERCLOCK_STEPSIZE  28000000
 #define OVERCLOCK_MAX_VOLT  1575
 
+// Industrial temperature chips may require different parameters
+// https://forum.pjrc.com/index.php?threads/75798/#post-349215
 
 uint32_t set_arm_clock(uint32_t frequency);
 
@@ -176,3 +178,37 @@ uint32_t set_arm_clock(uint32_t frequency)
 	return frequency;
 }
 
+#ifdef ARDUINO_TEENSY41
+void set_psram_clock(int speed_mhz) {
+    // What clocks exist:
+    static const int flexspio2_clock_speeds[] = { 396, 720, 665, 528 };
+
+    // See what the closest setting might be:
+    uint8_t clk_save = 0;
+    uint8_t divider_save =0;
+    int min_delta = speed_mhz;
+    for (uint8_t clk = 0; clk < 4; clk++) {
+        uint8_t divider = (flexspio2_clock_speeds[clk] + (speed_mhz / 2)) / speed_mhz;
+        int delta = abs(speed_mhz - flexspio2_clock_speeds[clk] / divider);
+        if ((delta < min_delta) && (divider < 8)) {
+            min_delta = delta;
+            clk_save = clk;
+            divider_save = divider;
+        }
+    }
+
+    // first turn off FLEXSPI2
+    CCM_CCGR7 &= ~CCM_CCGR7_FLEXSPI2(CCM_CCGR_ON);
+
+    divider_save--; // 0 biased.
+    //Serial.printf("Update FLEXSPI2 speed: %u clk:%u div:%u Actual:%u\n", speed_mhz, clk_save, divider_save,
+    //    flexspio2_clock_speeds[clk_save]/ (divider_save + 1));
+
+    // Set the clock settings.
+    CCM_CBCMR = (CCM_CBCMR & ~(CCM_CBCMR_FLEXSPI2_PODF_MASK | CCM_CBCMR_FLEXSPI2_CLK_SEL_MASK))
+                | CCM_CBCMR_FLEXSPI2_PODF(divider_save) | CCM_CBCMR_FLEXSPI2_CLK_SEL(clk_save);
+
+    // Turn FlexSPI2 clock back on
+    CCM_CCGR7 |= CCM_CCGR7_FLEXSPI2(CCM_CCGR_ON);
+}
+#endif
\ No newline at end of file
diff --git a/teensy4/core_cmInstr.h b/teensy4/core_cmInstr.h
index 971ae7e9..bfdfcacd 100644
--- a/teensy4/core_cmInstr.h
+++ b/teensy4/core_cmInstr.h
@@ -316,7 +316,7 @@ __attribute__( ( always_inline ) ) __STATIC_INLINE void __CLREX(void)
  */
 #define __SSAT(ARG1,ARG2) \
 ({                          \
-  uint32_t __RES, __ARG1 = (ARG1); \
+  int32_t __RES, __ARG1 = (ARG1); \
   __ASM ("ssat %0, %1, %2" : "=r" (__RES) :  "I" (ARG2), "r" (__ARG1) ); \
   __RES; \
  })
diff --git a/teensy4/core_pin_names.h b/teensy4/core_pin_names.h
new file mode 100644
index 00000000..c4c522c7
--- /dev/null
+++ b/teensy4/core_pin_names.h
@@ -0,0 +1,87 @@
+ #pragma once
+
+// PinName values: 32 bit top 16 - offset in EMC table, low 8 bits 0-4 GPIO PIN 5-7 On Port #
+typedef enum {
+	AD_B0_00 = 0x0BC0000, AD_B0_01 = 0x0C00001, AD_B0_02 = 0x0C40002, AD_B0_03 = 0x0C80003, AD_B0_04 = 0x0CC0004, AD_B0_05 = 0x0D00005, AD_B0_06 = 0x0D40006, AD_B0_07 = 0x0D80007,
+	AD_B0_08 = 0x0DC0008, AD_B0_09 = 0x0E00009, AD_B0_10 = 0x0E4000A, AD_B0_11 = 0x0E8000B, AD_B0_12 = 0x0EC000C, AD_B0_13 = 0x0F0000D, AD_B0_14 = 0x0F4000E, AD_B0_15 = 0x0F8000F,
+	AD_B1_00 = 0x0FC0010, AD_B1_01 = 0x1000011, AD_B1_02 = 0x1040012, AD_B1_03 = 0x1080013, AD_B1_04 = 0x10C0014, AD_B1_05 = 0x1100015, AD_B1_06 = 0x1140016, AD_B1_07 = 0x1180017,
+	AD_B1_08 = 0x11C0018, AD_B1_09 = 0x1200019, AD_B1_10 = 0x124001A, AD_B1_11 = 0x128001B, AD_B1_12 = 0x12C001C, AD_B1_13 = 0x130001D, AD_B1_14 = 0x134001D, AD_B1_15 = 0x138001F,
+	B0_00 = 0x13C0020, B0_01 = 0x1400021, B0_02 = 0x1440022, B0_03 = 0x1480023, B0_04 = 0x14C0024, B0_05 = 0x1500025, B0_06 = 0x1540026, B0_07 = 0x1580027,
+	B0_08 = 0x15C0028, B0_09 = 0x1600029, B0_10 = 0x164002A, B0_11 = 0x168002B, B0_12 = 0x16C002C, B0_13 = 0x170002D, B0_14 = 0x174002E, B0_15 = 0x178002F,
+	B1_00 = 0x17C0030, B1_01 = 0x1800031, B1_02 = 0x1840032, B1_03 = 0x1880033, B1_04 = 0x18C0034, B1_05 = 0x1900035, B1_06 = 0x1940036, B1_07 = 0x1980037,
+	B1_08 = 0x19C0038, B1_09 = 0x1A00039, B1_10 = 0x1A4003A, B1_11 = 0x1A8003B, B1_12 = 0x1AC003C, B1_13 = 0x1B0003D, B1_14 = 0x1B4003D, B1_15 = 0x1B8003F,
+	EMC_00 = 0x0140060, EMC_01 = 0x0180061, EMC_02 = 0x01C0062, EMC_03 = 0x0200063, EMC_04 = 0x0240064, EMC_05 = 0x0280065, EMC_06 = 0x02C0066, EMC_07 = 0x0300067,
+	EMC_08 = 0x0340068, EMC_09 = 0x0380069, EMC_10 = 0x03C006A, EMC_11 = 0x040006B, EMC_12 = 0x044006C, EMC_13 = 0x048006D, EMC_14 = 0x04C006E, EMC_15 = 0x050006F,
+	EMC_16 = 0x0540070, EMC_17 = 0x0580071, EMC_18 = 0x05C0072, EMC_19 = 0x0600073, EMC_20 = 0x0640074, EMC_21 = 0x0680075, EMC_22 = 0x06C0076, EMC_23 = 0x0700077,
+	EMC_24 = 0x0740078, EMC_25 = 0x0780079, EMC_26 = 0x07C007A, EMC_27 = 0x080007B, EMC_28 = 0x084007C, EMC_29 = 0x088007D, EMC_30 = 0x08C007D, EMC_31 = 0x090007F,
+	EMC_32 = 0x0940052, EMC_33 = 0x0980053, EMC_34 = 0x09C0054, EMC_35 = 0x0A00055, EMC_36 = 0x0A40056, EMC_37 = 0x0A80057, EMC_38 = 0x0AC0058, EMC_39 = 0x0B00059,
+	EMC_40 = 0x0B4005A, EMC_41 = 0x0B8005B, SD_B0_00 = 0x1BC004C, SD_B0_01 = 0x1C0004D, SD_B0_02 = 0x1C4004E, SD_B0_03 = 0x1C8004F, SD_B0_04 = 0x1CC0050, SD_B0_05 = 0x1D00051,
+	SD_B1_00 = 0x1D40040, SD_B1_01 = 0x1D80041, SD_B1_02 = 0x1DC0042, SD_B1_03 = 0x1E00043, SD_B1_04 = 0x1E40044, SD_B1_05 = 0x1E80045, SD_B1_06 = 0x1EC0046, SD_B1_07 = 0x1F00047,
+	SD_B1_08 = 0x1F40048, SD_B1_09 = 0x1F80049, SD_B1_10 = 0x1FC004A, SD_B1_11 = 0x200004B
+} IMXRT_PIN_t;
+
+//#define digitalPinToPort(pin)    (pin)
+inline uint32_t digitalPinNameToBitMask(IMXRT_PIN_t pin_name) 				{return  1 << (pin_name & 0x1f);}
+inline uint32_t digitalPinNameToBit(IMXRT_PIN_t pin_name) 					{return  (pin_name & 0x1f); }
+//inline volatile uint32_t * pinNamePortOutputRegister(IMXRT_PIN_t pin_name) { return }
+inline volatile uint32_t * pinNamePortSetRegister(IMXRT_PIN_t pin_name) 	{ return (volatile uint32_t*)((uint8_t *)&GPIO6_DR_SET + 0x4000 * ((pin_name >> 5) & 0x7));}
+inline volatile uint32_t * pinNamePortClearRegister(IMXRT_PIN_t pin_name) 	{ return (volatile uint32_t*)((uint8_t *)&GPIO6_DR_CLEAR + 0x4000 * ((pin_name >> 5) & 0x7));}
+inline volatile uint32_t * pinNamePortToggleRegister(IMXRT_PIN_t pin_name) 	{ return (volatile uint32_t*)((uint8_t *)&GPIO6_DR_TOGGLE + 0x4000 * ((pin_name >> 5) & 0x7));}
+inline volatile uint32_t * pinNamePortInputRegister(IMXRT_PIN_t pin_name) { return (volatile uint32_t*)((uint8_t *)&GPIO6_PSR + 0x4000 * ((pin_name >> 5) & 0x7));}
+inline volatile uint32_t * pinNamePortModeRegister(IMXRT_PIN_t pin_name) { return (volatile uint32_t *)(IMXRT_IOMUXC_ADDRESS + (pin_name >> 16));}
+inline volatile uint32_t * pinNamePortConfigRegister(IMXRT_PIN_t pin_name) { return (volatile uint32_t *)(IMXRT_IOMUXC_ADDRESS + (pin_name >> 16) + 0x1f0);}
+//inline volatile uint32_t * pinNamePortControlRegister(IMXRT_PIN_t pin_name) { return }
+//#define digitalPinToPortReg(pin) (portOutputRegister(pin))
+
+inline void digitalWrite(IMXRT_PIN_t pin_name, uint8_t val) {
+	uint32_t mask = 1 << (pin_name & 0x1f);
+	if (val) {
+		volatile uint32_t *reg = (volatile uint32_t*)((uint8_t *)&GPIO6_DR_SET + 0x4000 * ((pin_name >> 5) & 0x7));
+		*reg = mask;
+	} else {
+		volatile uint32_t *reg = (volatile uint32_t*)((uint8_t *)&GPIO6_DR_CLEAR + 0x4000 * ((pin_name >> 5) & 0x7));
+		*reg = mask;
+	}
+}
+inline void digitalToggle(IMXRT_PIN_t pin_name) {
+	uint32_t mask = 1 << (pin_name & 0x1f);
+	volatile uint32_t *reg = (volatile uint32_t*)((uint8_t *)&GPIO6_DR_TOGGLE + 0x4000 * ((pin_name >> 5) & 0x7));
+	//Serial.printf("Toggle %x Reg:%x mask:%x\n", pin_name, reg, mask);
+	*reg = mask;
+}
+
+inline uint8_t digitalRead(IMXRT_PIN_t pin_name) {
+	return (*pinNamePortInputRegister(pin_name) & digitalPinNameToBitMask(pin_name))? 1 : 0;
+}
+
+void pinMode(IMXRT_PIN_t pin_name, uint8_t mode)
+{
+	// generate PAD and MUX register from name...
+	volatile uint32_t *mux = (volatile uint32_t *)(IMXRT_IOMUXC_ADDRESS + (pin_name >> 16));
+	volatile uint32_t *pad = (volatile uint32_t *)(IMXRT_IOMUXC_ADDRESS + (pin_name >> 16) + 0x1f0);
+	volatile uint32_t *gdir = (volatile uint32_t*)((uint8_t *)&GPIO6_GDIR + 0x4000 * ((pin_name >> 5) & 0x7));
+	uint32_t mask = 1 << (pin_name & 0x1f);
+
+	Serial.printf("pinMode %x mux:%p pad:%p gdir:%p mask:%x\n", pin_name, mux, pad, gdir, mask);
+
+	if (mode == OUTPUT || mode == OUTPUT_OPENDRAIN) {
+		*gdir |= mask; // TODO: atomic
+		if (mode == OUTPUT) {
+			*pad = IOMUXC_PAD_DSE(7);
+		} else { // OUTPUT_OPENDRAIN
+			*pad = IOMUXC_PAD_DSE(7) | IOMUXC_PAD_ODE;
+		}
+	} else {
+		*gdir &= ~(mask); // TODO: atomic
+		if (mode == INPUT) {
+			*pad = IOMUXC_PAD_DSE(7);
+		} else if (mode == INPUT_PULLUP) {
+			*pad = IOMUXC_PAD_DSE(7) | IOMUXC_PAD_PKE | IOMUXC_PAD_PUE | IOMUXC_PAD_PUS(3) | IOMUXC_PAD_HYS;
+		} else if (mode == INPUT_PULLDOWN) {
+			*pad = IOMUXC_PAD_DSE(7) | IOMUXC_PAD_PKE | IOMUXC_PAD_PUE | IOMUXC_PAD_PUS(0) | IOMUXC_PAD_HYS;
+		} else { // INPUT_DISABLE
+			*pad = IOMUXC_PAD_DSE(7) | IOMUXC_PAD_HYS;
+		}
+	}
+	*mux = (uint8_t)(5 | 0x10);
+}
diff --git a/teensy4/core_pins.h b/teensy4/core_pins.h
index 15b4f6bc..c6fcb615 100644
--- a/teensy4/core_pins.h
+++ b/teensy4/core_pins.h
@@ -47,8 +47,11 @@
 #define FALLING			2
 #define RISING			3
 
-
-#if defined(__IMXRT1062__) && defined(ARDUINO_TEENSY40)
+#if __has_include("variant.h")
+#  include "variant.h"
+//#pragma message "core_pins.h" - included variant.h
+// Default no override file
+#elif defined(__IMXRT1062__) && defined(ARDUINO_TEENSY40)
 
 #define CORE_NUM_TOTAL_PINS	40
 #define CORE_NUM_DIGITAL	40
@@ -1911,6 +1914,8 @@ static inline void digitalWriteFast(uint8_t pin, uint8_t val)
 			} else if (pin == 54) {
 				CORE_PIN54_PORTSET = CORE_PIN54_BITMASK;
 #endif
+			} else if (pin < CORE_NUM_DIGITAL) {
+				*portSetRegister(pin) = digitalPinToBitMask(pin);
 			}
 		} else {
 			if (pin == 0) {
@@ -2027,9 +2032,12 @@ static inline void digitalWriteFast(uint8_t pin, uint8_t val)
 			} else if (pin == 54) {
 				CORE_PIN54_PORTCLEAR = CORE_PIN54_BITMASK;
 #endif
+			} else if (pin < CORE_NUM_DIGITAL) {
+				*portClearRegister(pin) = digitalPinToBitMask(pin);
 			}
+
 		}
-	} else {
+	} else if (pin < CORE_NUM_DIGITAL) {
 		if(val) *portSetRegister(pin) = digitalPinToBitMask(pin);
 		else *portClearRegister(pin) = digitalPinToBitMask(pin);
 	}
@@ -2161,11 +2169,15 @@ static inline uint8_t digitalReadFast(uint8_t pin)
 		} else if (pin == 54) {
 			return (CORE_PIN54_PINREG & CORE_PIN54_BITMASK) ? 1 : 0;
 #endif
+		} else if (pin < CORE_NUM_DIGITAL) {
+			return (*portInputRegister(pin) & digitalPinToBitMask(pin)) ? 1 : 0;
 		} else {
 			return 0;
 		}
-	} else {
+	} else if (pin < CORE_NUM_DIGITAL) {
 		return (*portInputRegister(pin) & digitalPinToBitMask(pin)) ? 1 : 0;
+	} else {
+		return 0;
 	}
 }
 
@@ -2295,9 +2307,11 @@ static inline void digitalToggleFast(uint8_t pin)
 		} else if (pin == 54) {
 			CORE_PIN54_PORTTOGGLE = CORE_PIN54_BITMASK;
 #endif
+		} else {
+			digitalToggle(pin);
 		}
-	} else {
-		digitalToggle(pin);
+	} else if (pin < CORE_NUM_DIGITAL) {
+		*portToggleRegister(pin) = digitalPinToBitMask(pin);
 	}
 }
 
diff --git a/teensy4/digital.c b/teensy4/digital.c
index 587effd4..3129a6d6 100644
--- a/teensy4/digital.c
+++ b/teensy4/digital.c
@@ -21,7 +21,7 @@ extern const struct digital_pin_bitband_and_config_table_struct digital_pin_to_i
 #define digitalPinToPortReg(pin) (portOutputRegister(pin))
 */
 
-const struct digital_pin_bitband_and_config_table_struct digital_pin_to_info_PGM[] = {
+const struct digital_pin_bitband_and_config_table_struct digital_pin_to_info_PGM[]  __attribute__((weak)) = {
 	{&CORE_PIN0_PORTREG, &CORE_PIN0_CONFIG, &CORE_PIN0_PADCONFIG, CORE_PIN0_BITMASK},
 	{&CORE_PIN1_PORTREG, &CORE_PIN1_CONFIG, &CORE_PIN1_PADCONFIG, CORE_PIN1_BITMASK},
 	{&CORE_PIN2_PORTREG, &CORE_PIN2_CONFIG, &CORE_PIN2_PADCONFIG, CORE_PIN2_BITMASK},
diff --git a/teensy4/extmem.c b/teensy4/extmem.c
index 1000b1b8..27db8423 100644
--- a/teensy4/extmem.c
+++ b/teensy4/extmem.c
@@ -45,7 +45,7 @@ void *extmem_calloc(size_t nmemb, size_t size)
 void *extmem_realloc(void *ptr, size_t size)
 {
 #ifdef HAS_EXTRAM
-	if (IS_EXTMEM(ptr)) {
+	if (IS_EXTMEM(ptr) || ptr == NULL) {
 		return sm_realloc_pool(&extmem_smalloc_pool, ptr, size);
 	}
 #endif
diff --git a/teensy4/new.cpp b/teensy4/new.cpp
index 51ce141e..606cfc58 100644
--- a/teensy4/new.cpp
+++ b/teensy4/new.cpp
@@ -23,7 +23,8 @@
  * SOFTWARE.
  */
 
-#include <stdlib.h>
+#include <cstdlib>
+#include <new>
 
 void * operator new(size_t size)
 {
@@ -55,3 +56,32 @@ void operator delete[](void * ptr, size_t size __attribute__((unused)))
 	free(ptr);
 }
 
+void * operator new(size_t size, std::align_val_t align)
+{
+	return aligned_alloc((size_t)align, size);
+}
+
+void * operator new[](size_t size, std::align_val_t align)
+{
+	return aligned_alloc((size_t)align, size);
+}
+
+void operator delete(void * ptr, std::align_val_t align __attribute__((unused)))
+{
+	free(ptr);
+}
+
+void operator delete[](void * ptr, std::align_val_t align __attribute__((unused)))
+{
+	free(ptr);
+}
+
+void operator delete(void * ptr, size_t size __attribute__((unused)), std::align_val_t align __attribute__((unused)))
+{
+	free(ptr);
+}
+
+void operator delete[](void * ptr, size_t size __attribute__((unused)), std::align_val_t align __attribute__((unused)))
+{
+	free(ptr);
+}
diff --git a/teensy4/pwm.c b/teensy4/pwm.c
index 9800f4d7..b023ce87 100644
--- a/teensy4/pwm.c
+++ b/teensy4/pwm.c
@@ -16,7 +16,7 @@ uint8_t analog_write_res = 8;
 
 #if defined(__IMXRT1062__)
 
-const struct pwm_pin_info_struct pwm_pin_info[] = {
+const struct pwm_pin_info_struct pwm_pin_info[]  __attribute__((weak)) = {
 	{1, M(1, 1), 0, 4},  // FlexPWM1_1_X   0  // AD_B0_03
 	{1, M(1, 0), 0, 4},  // FlexPWM1_0_X   1  // AD_B0_02
 	{1, M(4, 2), 1, 1},  // FlexPWM4_2_A   2  // EMC_04
diff --git a/teensy4/startup.c b/teensy4/startup.c
index 2375f26c..4bb3bd40 100644
--- a/teensy4/startup.c
+++ b/teensy4/startup.c
@@ -318,6 +318,9 @@ FLASHMEM void configure_cache(void)
 
 	SCB_MPU_RBAR = 0x70000000 | REGION(i++); // FlexSPI2
 	SCB_MPU_RASR = MEM_CACHE_WBWA | READWRITE | NOEXEC | SIZE_16M;
+	// We default RAM meant for data to NOEXEC as a proactive security measure.
+	// If you wish to dynamically load code into RAM and execute it, start here:
+	// https://forum.pjrc.com/index.php?threads/75610/#post-347791
 
 	SCB_MPU_RBAR = 0x80000000 | REGION(i++); // SEMC: SDRAM, NAND, SRAM, etc
 	SCB_MPU_RASR = MEM_CACHE_WBWA | READWRITE | NOEXEC | SIZE_1G;