ports/samd/boards: Add support for Adafruit Grand Central M4.

Include QSPI pin definitions suggested by @robert-hh, and link photograph
of board referenced from micropython-media. Also includes definitions to
allow SD card use, so bake in sdcard driver, and point at 8MB QSPI flash
for file system. ATSAMD51P20A has room for ~1MB compiled code so use.

Includes updated pins.csv from @robert-hh

Co-authored-by: robert-hh <[email protected]>
Signed-off-by: Graeme Winter <[email protected]>

ports/samd/boards/ADAFRUIT_GRAND_CENTRAL_M4_EXPRESS/board.json

@@ -0,0 +1,19 @@
+{
+    "deploy": [
+        "../deploy.md"
+    ],
+    "docs": "",
+    "features": [
+        "External Flash",
+        "RGB LED",
+        "USB"
+    ],
+    "mcu": "samd51",
+    "product": "Grand Central M4 Express",
+    "images": [
+        "grand_central_m4_express.jpg"
+    ],
+    "thumbnail": "",
+    "url": "https://www.adafruit.com/product/4064",
+    "vendor": "Adafruit"
+}

ports/samd/boards/ADAFRUIT_GRAND_CENTRAL_M4_EXPRESS/manifest.py

@@ -0,0 +1,6 @@
+include("$(PORT_DIR)/boards/manifest.py")
+include("$(MPY_DIR)/extmod/asyncio")
+require("onewire")
+require("ds18x20")
+require("neopixel")
+require("sdcard")

ports/samd/boards/ADAFRUIT_GRAND_CENTRAL_M4_EXPRESS/mpconfigboard.h

@@ -0,0 +1,13 @@
+#define MICROPY_HW_BOARD_NAME "Grand Central M4 Express"
+#define MICROPY_HW_MCU_NAME   "ATSAMD51P20A"
+
+#define MICROPY_HW_XOSC32K          (1)
+
+// 8MB QSPI chip
+#define MICROPY_HW_QSPIFLASH GD25Q64C
+
+// fatfs configuration used in ffconf.h
+#define MICROPY_FATFS_ENABLE_LFN         (1)
+#define MICROPY_FATFS_RPATH              (2)
+#define MICROPY_FATFS_MAX_SS             (4096)
+#define MICROPY_FATFS_LFN_CODE_PAGE      437 /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */

ports/samd/boards/ADAFRUIT_GRAND_CENTRAL_M4_EXPRESS/mpconfigboard.mk

@@ -0,0 +1,13 @@
+MCU_SERIES = SAMD51
+CMSIS_MCU = ATSAMD51P20A
+LD_FILES = boards/samd51x20a.ld sections.ld
+TEXT0 = 0x4000
+
+# The ?='s allow overriding in mpconfigboard.mk.
+# MicroPython settings
+MICROPY_VFS_LFS1 ?= 1
+
+FROZEN_MANIFEST = $(BOARD_DIR)/manifest.py
+
+# Greater room for code in flash
+MICROPY_HW_CODESIZE ?= 1008K

ports/samd/boards/ADAFRUIT_GRAND_CENTRAL_M4_EXPRESS/pins.csv

@@ -0,0 +1,98 @@
+# The lines contain pairs of Pin name and Pin number.
+# Pin names must be valid Python identifiers.
+# Pin numbers have the form Pxnn, with x being A, B, C or D.
+# Lines starting with # or empty lines are ignored.
+
+A0,PA02
+A1,PA05
+A2,PB03
+A10,PB07
+A11,PB08
+A12,PB09
+A13,PA04
+A14,PA06
+A15,PA07
+A3,PC00
+A4,PC01
+A5,PC02
+A6,PC03
+A7,PB04
+A8,PB05
+A9,PB06
+AREF,PA03
+CS,PD10
+D0,PB25
+D1,PB24
+D10,PB22
+D11,PB23
+D12,PB00
+D13,PB01
+D2,PC18
+D22,PD12
+D23,PA15
+D3,PC19
+D4,PC20
+D44,PC11
+D45,PC10
+D46,PC06
+D47,PC07
+D48,PC04
+D49,PC05
+D5,PC21
+D6,PD20
+D7,PD21
+D8,PB18
+D9,PB02
+MISO,PD11
+MOSI,PD08
+NEOPIXEL,PC24
+PCC_CLK,PA14
+PCC_D0,PA16
+PCC_D1,PA17
+PCC_D10,PC12
+PCC_D11,PC13
+PCC_D12,PC14
+PCC_D13,PC15
+PCC_D2,PA18
+PCC_D3,PA19
+PCC_D4,PA20
+PCC_D5,PA21
+PCC_D6,PA22
+PCC_D7,PA23
+PCC_D8,PB14
+PCC_D9,PB15
+PCC_DEN1,PA12
+PCC_DEN2,PA13
+PCC_XCLK,PB19
+RX1,PB13
+RX2,PC23
+RX3,PB17
+RXLED,PC31
+SCK,PD09
+SCL,PB21
+SCL_1,PC17
+SD_CD,PB31
+SD_CS,PB28
+SD_MISO,PB29
+SD_MOSI,PB26
+SD_SCK,PB27
+SDA,PB20
+SDA_1,PC16
+SWO,PB30
+TX1,PB12
+TX2,PC22
+TX3,PB16
+TXLED,PC30
+
+QSPI_CS,PB11
+QSPI_SCK,PB10
+QSPI_D0,PA08
+QSPI_D1,PA09
+QSPI_D2,PA10
+QSPI_D3,PA11
+
+USB_DM,PA24
+USB_DP,PA25
+
+SWCLK,PA30
+SWDIO,PA31