Diff: INA219.cpp

Revision:

0:eee9c8ba72ff

Child:

1:8ccc8e47e3d5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/INA219.cpp	Thu Aug 28 10:32:20 2014 +0000
@@ -0,0 +1,88 @@
+#include "INA219.hpp"
+
+INA219::INA219 (PinName sda, PinName scl, int addr, int freq, resolution_t res) : I2C(sda, scl), resolution(res), i2c_addr(addr << 1)
+{
+    I2C::frequency(freq);
+    
+    // by default, calibrate to this level.
+    calibrate_16v_400mA();
+}
+
+// Private Methods
+
+void INA219::write_register (uint8_t reg, uint8_t* data, int length)
+{
+    char* transmission = (char*)malloc(length + 1);
+    memcpy(transmission + 1, data, length);
+
+    transmission[0] = reg;
+    I2C::write(i2c_addr, transmission, length + 1);
+
+    free(transmission);
+}
+
+void INA219::write_register_u16 (uint8_t reg, uint16_t data)
+{
+    char transmission[3];
+    transmission[0] = reg;
+    transmission[1] = (data >> 8) & 0xff;
+    transmission[2] = data & 0xff;
+
+    I2C::write(i2c_addr, transmission, 3);
+}
+
+void INA219::write_null(uint8_t reg) {
+    I2C::write(i2c_addr, (char*)&reg, 1);    
+}
+
+uint16_t INA219::read_register_u16 (uint8_t reg)
+{
+    write_null(reg);
+
+    char data[2];
+    I2C::read(i2c_addr, data, 2);
+
+    uint16_t ret_val = data[0] << 8 | data[1];
+    return ret_val;
+}
+
+// Public Methods
+
+void INA219::calibrate_16v_400mA()
+{
+    // ASSUMING A 0.1 OHM RESISTOR!
+    write_register_u16(INA219_REG_CALIBRATION, 8192);
+
+    // Write to config register
+
+    uint16_t resolution_mask = 0x0000;
+    
+    if (resolution == RES_12BITS)
+        resolution_mask = INA219_CONFIG_BADCRES_12BIT | INA219_CONFIG_SADCRES_12BIT_1S_532US;
+    else if (resolution == RES_11BITS)
+        resolution_mask = INA219_CONFIG_BADCRES_11BIT | INA219_CONFIG_SADCRES_11BIT_1S_276US;
+    else if (resolution == RES_10BITS)
+        resolution_mask = INA219_CONFIG_BADCRES_10BIT | INA219_CONFIG_SADCRES_10BIT_1S_148US;
+    else // resolution == RES_9BITS
+        resolution_mask = INA219_CONFIG_BADCRES_9BIT | INA219_CONFIG_SADCRES_9BIT_1S_84US;
+
+    write_register_u16(INA219_REG_CONFIG, INA219_CONFIG_BVOLTAGERANGE_16V |
+                    INA219_CONFIG_GAIN_1_40MV |
+                    resolution_mask |
+                    INA219_CONFIG_MODE_SANDBVOLT_CONTINUOUS);
+                    
+    // Set current divider
+    current_divider = 20;
+    power_divider = 1;
+}
+
+int16_t INA219::read_current_raw()
+{
+    return (int16_t)read_register_u16(INA219_REG_CURRENT);
+}
+
+float INA219::read_current_mA()
+{
+    float raw_current = read_current_raw();
+    return raw_current / current_divider;
+}
\ No newline at end of file