Initial commit

src/ads1115.c

@@ -0,0 +1,100 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <syslog.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#include <ads1115.h>
+
+#define BUF_SIZE        3
+#define VPS             6.144 / 32768.0
+
+int ads1115_open(const struct ads1115_dev *ads1115)
+{
+    int res;
+
+    assert(NULL != ads1115);
+
+    syslog(LOG_DEBUG, "Trying to open i2c_bb.\n");
+    res = i2c_open(ads1115->i2c_dev);
+    if(res != 0) {
+        syslog(LOG_ERR, "Unable to open i2c_bb.\n");
+        return res;
+    }
+    syslog(LOG_DEBUG, "i2c dev successfully opened.\n");
+
+    return 0;
+}
+
+int ads1115_close(const struct ads1115_dev *ads1115)
+{
+    assert(NULL != ads1115);
+
+    return i2c_close(ads1115->i2c_dev);
+}
+
+int ads1115_start_conversation(const struct ads1115_dev *ads1115)
+{
+    int res;
+    char buffer[BUF_SIZE];
+
+    assert(NULL != ads1115);
+
+    syslog(LOG_DEBUG, "ads1115 start conversation.\n");
+
+    /* FIXME: prevent hard coded config. */
+    buffer[0] = 0b00000001; // config register @ address 1
+    buffer[1] = 0b11000001; // config value high byte
+    buffer[2] = 0b10000111; // config value low byte
+
+    // begin conversation
+    res = i2c_write(ads1115->i2c_dev, ads1115->i2c_slave_address, buffer, BUF_SIZE);
+    if(res != BUF_SIZE) {
+        syslog(LOG_ERR, "Unable to write to ADS1115.\n");
+        i2c_close(ads1115->i2c_dev);
+        return res;
+    }
+    syslog(LOG_DEBUG, "ads1115 conversation done.\n");
+
+    return 0;
+}
+
+int ads1115_read_conversation_result(const struct ads1115_dev *ads1115,
+                                     struct ads1115_conversation_result *result)
+{
+    int res;
+    char buffer[BUF_SIZE];
+
+    assert(NULL != ads1115);
+    assert(NULL != result);
+
+    // wait for conversation complete
+    do {
+        res = i2c_read(ads1115->i2c_dev, ads1115->i2c_slave_address, buffer, 2);
+        if(res != 2) {
+            syslog(LOG_ERR, "Unable to read from ADS1115.\n");
+            return res;
+        }
+    } while((buffer[0] & 0x80) == 0);
+
+    // read conversation result
+    buffer[0] = 0b00000000;   /* conversation register at address 0b00000000 */
+    res = i2c_write(ads1115->i2c_dev, ads1115->i2c_slave_address, buffer, 1);
+    if(res != 1) {
+        syslog(LOG_ERR, "Unable to write to ADS1115.\n");
+        return res;
+    }
+
+    // read 2 bytes
+    res = i2c_read(ads1115->i2c_dev, ads1115->i2c_slave_address, buffer, 2);
+    if(res != 2) {
+        syslog(LOG_ERR, "Unable to read from ADS1115.\n");
+        return res;
+    }
+    result->raw = buffer[0] << 8 | buffer[1];
+    result->voltage = result->raw * VPS;
+
+    return 0;
+}