ads1115 analog-to-digital 4-channel added

diff --git a/ads1115.c b/ads1115.c
new file mode 100644 (file)
index 0000000..f1fa0de
--- /dev/null
+++ b/ads1115.c
@@ -0,0 +1,83 @@
+
+#include <stdio.h>
+#include <sys/types.h> // open
+#include <sys/stat.h>  // open
+#include <fcntl.h>     // open
+#include <unistd.h>    // read/write usleep
+#include <stdlib.h>    // exit
+#include <inttypes.h>  // uint8_t, etc
+#include <linux/i2c-dev.h> // I2C bus definitions
+
+float getVin(int pin) {
+
+  int fd;
+  int ads_address = 0x48;
+
+  uint8_t buf[10];
+  int16_t val;
+  uint8_t pinCodes[4];
+
+  pinCodes[0]=0xc3;
+  pinCodes[1]=0xd3;
+  pinCodes[2]=0xe3;
+  pinCodes[3]=0xf3;
+
+  // open device on /dev/i2c-0
+  if ((fd = open("/dev/i2c-0", O_RDWR)) < 0) {
+    printf("Error: Couldn't open device! %d\n", fd);
+    return 1;
+  }
+
+  // connect to ads1115 as i2c slave
+  if (ioctl(fd, I2C_SLAVE, ads_address) < 0) {
+    printf("Error: Couldn't find device on address!\n");
+    return 1;
+  }
+     
+  // AIN0 and GND, 4.096v, 128s/s
+
+  buf[0] = 1;    // config register is 1
+  buf[1] = pinCodes[pin];
+  buf[2] = 0x85;
+  if (write(fd, buf, 3) != 3) {
+    perror("Write to register 1");
+    exit(-1);
+  }
+
+  usleep(10000);
+
+  // wait for conversion complete
+  do {
+    if (read(fd, buf, 2) != 2) {
+      perror("Read conversion");
+      exit(-1);
+    }
+  } while (buf[0] & 0x80 == 0);
+
+  // read conversion register
+  buf[0] = 0;   // conversion register is 0
+  if (write(fd, buf, 1) != 1) {
+    perror("Write register select");
+    exit(-1);
+  }
+  if (read(fd, buf, 2) != 2) {
+    perror("Read conversion");
+    exit(-1);
+  }
+
+  // convert output and display results
+  val = (int16_t)buf[0]*256 + (uint16_t)buf[1];
+  
+  close(fd);
+
+  return (float)val*4.096/32768.0;
+}
+
+main() {
+
+  int i;
+  for ( i=0; i<=3; i++) {
+    printf("Vin%1d (V) %5.3f\n",i,getVin(i));
+  }
+
+}