Canberk Sönmez
LTC2945 ported
Diff: main.cpp
- Revision:
- 3:2ab78e7e8518
- Parent:
- 2:7e390bcce297
--- a/main.cpp Fri Aug 25 07:46:48 2017 +0000
+++ b/main.cpp Fri Aug 25 14:42:14 2017 +0000
@@ -1,63 +1,121 @@
-#include "mbed.h"
+/**
+ * Canberk Sönmez,
+ * code is taken from the official tutorial for Linduino platform.
+ *
+ * I couldn't get power measurement working.
+ */
+
+#include <mbed.h>
#include <I2C.h>
#include "LT_I2C.h"
#include "LTC2945.h"
-I2C i2c(p9, p10);
-// sda, scl
+/* initialize I2C communications object */
+I2C i2c(p28, p27);
+/* sda, scl */
-extern I2C* i2c_object;
-
-Serial pc(USBTX, USBRX);
-
+/* LTC2945 I2C address, it's shifted 1 bit right,
+ * as it's given in 8-bit form in the datasheet,
+ * and the library does shifting again, causing
+ * communication problems
+ * 0xDE, since ADR0 and ADR1 are both grounded. */
const int ltc2945_addr = 0xDE>>1;
-int test_write(int byte) {
- return i2c_object->write(byte);
-}
+/* ASSERT macro, reports debugging information if
+ * the condition inside paranthesis is not satisfied. */
+#define ASSERT(x) if (! (x)) { printf("%s:%d %s failed!\n", \
+ __FILE__, __LINE__, #x); }
-#define ASSERT(x) if (! (x)) { printf("%s:%d %s failed!\n", __FILE__, __LINE__, #x); }
-#define DEBUG_LINE printf("DEBUG: %s:%d\n", __FILE__, __LINE__);
+/*
+ * Program entry point.
+ */
+int main() {
+ /* initialize ported LT_I2C library and check if it's fine */
+ ASSERT(lt_i2c_init_attach(&i2c) == LT_I2C_INIT_FINE);
-int main() {
- ASSERT(lt_i2c_init_attach(&i2c) == LT_I2C_INIT_FINE);
- i2c.frequency(10000);
+ /* change I2C frequency, to have it working with optocoupled circuit */
+ i2c.frequency(1000);
- const float LTC2945_DELTA_SENSE_lsb = 2.5006105E-05; //!< Typical Delta lsb weight in volts
- const float LTC2945_VIN_lsb = 2.5006105E-02; //!< Typical VIN lsb weight in volts
- const float LTC2945_Power_lsb = 6.25305E-07; //!< Typical POWER lsb weight in V^2
+ /* typical LSB values, LSB is the smallest change in the value per least
+ * significant bit. */
+ // typical deltaSense LSB weight in volts
+ const float LTC2945_DELTA_SENSE_lsb = 2.5006105E-05;
+ // typical Vin LSB in volts
+ const float LTC2945_VIN_lsb = 2.5006105E-02;
+ // typical POWER LSB in V^2
+ const float LTC2945_Power_lsb = 6.25305E-07;
+ // power code, which is read as an integer and converted later
int32_t power_code;
+ // current code (same as above)
uint16_t current_code;
+ // Vin code (same as above)
uint16_t VIN_code;
+ // adc command is constructed and sent to the LTC2945
uint8_t adc_command;
+ // ACKnowledge bit, received if the operation is successful
int8_t ack;
+ // resistance value
float resistor;
+ // calculated power value
float power;
+ // calculated current value
float current;
+ // calculated VIN value
float VIN;
+ // the resistance value (calibrate if necessary)
+ resistor = 0.26518f;
+
+ // we are in an infinite loop, continuously print values
while (true) {
- ack = 0;
- adc_command = LTC2945_SENSE_MONITOR | LTC2945_CONTINUOUS_MODE; // Builds commands to set LTC2945 to continuous mode
- ack |= LTC2945_write(ltc2945_addr, LTC2945_CONTROL_REG, adc_command); // Sets the LTC2945 to continuous mode
- ASSERT(ack == 0);
- resistor = .0182445; // Resistor Value On Demo Board
+ ack = 0; // never forget resetting ack
+ // build adc_command, set LTC2945 in continuous mode
+ adc_command = LTC2945_SENSE_MONITOR | LTC2945_CONTINUOUS_MODE;
+ /* send command by LTC2945_write command.
+ * we use |= here not &= to accumulate success state
+ * as in the API 0 means successful, and 1 means failure.
+ * if we have ACKnowledge, then we are successful */
+ ack |= LTC2945_write(ltc2945_addr, LTC2945_CONTROL_REG, adc_command);
- ack |= LTC2945_read_24_bits(ltc2945_addr, LTC2945_POWER_MSB2_REG, &power_code); // Reads the ADC registers that contains V^2
- ASSERT(ack == 0);
- power = LTC2945_code_to_power(power_code, resistor, LTC2945_Power_lsb); // Calculates power from power code, resistor value and power lsb
+ /* read LTC2945_POWER_MSB2_REG register, containing power code
+ * (it's a 24-bit register) */
+ ack |= LTC2945_read_24_bits(
+ ltc2945_addr,
+ LTC2945_POWER_MSB2_REG,
+ &power_code);
+ /* and convert it to power, using LTC2945_code_to_power */
+ power = LTC2945_code_to_power(power_code, resistor, LTC2945_Power_lsb);
- ack |= LTC2945_read_12_bits(ltc2945_addr, LTC2945_DELTA_SENSE_MSB_REG, ¤t_code); // Reads the voltage code across sense resistor
+ /* read LTC2945_DELTA_SENSE_MSB_REG register, containing deltaSENSE
+ * voltage code (it's a 12-bit register) */
+ ack |= LTC2945_read_12_bits(
+ ltc2945_addr,
+ LTC2945_DELTA_SENSE_MSB_REG,
+ ¤t_code);
+ /* and convert it to current using resistance
+ * via LTC2945_code_to_current */
+ current = LTC2945_code_to_current(
+ current_code,
+ resistor,
+ LTC2945_DELTA_SENSE_lsb);
+
+ /* read LTC2945_VIN_MSB_REG register, containing Vin voltage code
+ * (it's a 12-bit register) */
+ ack |= LTC2945_read_12_bits(
+ ltc2945_addr,
+ LTC2945_VIN_MSB_REG,
+ &VIN_code);
+ /* and convert it to voltage directly */
+ VIN = LTC2945_VIN_code_to_voltage(VIN_code, LTC2945_VIN_lsb);
+
+ /* we must have ack = 0 if all the operations above are successful! */
ASSERT(ack == 0);
- current = LTC2945_code_to_current(current_code, resistor, LTC2945_DELTA_SENSE_lsb); // Calculates current from current code, resistor value and current lsb
-
- ack |= LTC2945_read_12_bits(ltc2945_addr, LTC2945_VIN_MSB_REG, &VIN_code); // Reads VIN voltage code
- ASSERT(ack == 0);
- VIN = LTC2945_VIN_code_to_voltage(VIN_code, LTC2945_VIN_lsb); // Calculates VIN voltage from VIN code and lsb
-
- printf("power: %f, current: %f, Vin: %f\n", power, current, VIN);
+ /* print it, only 2 digits after dot */
+ printf("power: %.2f, current: %.2f, Vin: %.2f\n", power, current, VIN);
+
+ /* wait 500 ms */
wait_ms(500);
}
}