adding example reading ADC7606

EXAMPLES_C/read_ADC7606_v1.c

@@ -0,0 +1,95 @@
+/* Reading data from an ADC7606 using parallel comms to an AGX Orin this is a
+ * naive approach, each 16 bits sample output  are read sequentially, this process takes approx. 20us
+ * per sample Vx
+ * Assumptions are: 
+ * 	CONVSTA & B start the conversion process, each conversion process needs arising edge from those pins
+ *	While conversion is taking place, pin BUSY is high (1)
+ * Compile with: gcc -Wall -o read_ADC7606_v1 read_ADC7606_v1.c -ljetgpio
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <jetgpio.h>
+
+//Giving meaningful names to pins in the Orin 
+#define CS_RD 3
+#define CONVST_AB 5
+#define BUSY 7
+
+//#define BILLION 1000000000L
+//uint64_t diff;
+//struct timespec start, end;
+
+int main(void) {
+
+  int Vx = 0;
+  //List of AGX data pins DB0 to DB15 = pin8 to 28 
+  int pin_level[16] = {0};
+  unsigned pin_number[16] = {8, 10, 11, 12, 13, 15, 16, 18, 19, 21, 22, 23, 24 \
+                             ,26, 27, 28};
+  gpioInitialise();
+
+  //Setting BUSY and data pins as inputs
+  for (unsigned i = 0;i < 16; i++) {
+    gpioSetMode(pin_number[i], JET_INPUT);
+  }
+  gpioSetMode(BUSY, JET_INPUT);
+
+  //Setting CS/RD and CONVSTA & B as outputs
+  gpioSetMode(CS_RD, JET_OUTPUT);
+  gpioSetMode(CONVST_AB, JET_OUTPUT);
+
+  //Setting CONVST to low level, intial state 
+  gpioWrite(CONVST_AB, 0);
+
+  //Setting CS & RD to high level, output is all at tri state, initial state
+  gpioWrite(CS_RD, 1);
+
+  while(1) {
+    //Measure how long it takes in nanoseconds
+    //clock_gettime(CLOCK_MONOTONIC, &start);
+
+    Vx = 0;
+
+    //Setting CONVST to high level, conversion starts 
+    gpioWrite(CONVST_AB, 1);
+
+    //Checking if BUSY is low (conversion completed) if not wait 1us
+    while(gpioRead(BUSY)) {
+      usleep(1);
+    }
+
+    //Enabling data output CS/RD to 0 to move to the next value
+    gpioWrite(CS_RD, 0);
+
+
+    //Reading all the data inputs pins this process will take approximately 16us
+    for (unsigned i = 0;i < 16; i++) {
+      pin_level[i] = gpioRead(pin_number[i]);
+    }
+
+    //Setting CS/RD to 1
+    gpioWrite(CS_RD, 1);
+
+    //Setting CONVST to 0
+    gpioWrite(CONVST_AB, 0);
+
+    //Calculating final result (sample Vx) here most significant bit is pin 15
+    for (unsigned i = 0;i < 16;i++) {
+
+      Vx |= pin_level[i] << i; 
+    }
+
+    printf("\r%d", Vx);
+
+    //clock_gettime(CLOCK_MONOTONIC, &end);
+    //diff = BILLION * (end.tv_sec - start.tv_sec) + end.tv_nsec - start.tv_nsec;
+    //printf("elapsed time = %llu nanoseconds\n", (long long unsigned int) diff);   
+  }
+
+  gpioTerminate();
+
+  return 0;
+}