current sense for solar sense (#210)

* current sense for solar sense

projects/solar_sense/inc/current_sense.h

@@ -0,0 +1,11 @@
+#pragma once
+#include <stdint.h>
+
+#include "gpio.h"
+#include "status.h"
+
+StatusCode current_sense_init(uint8_t conversion_speed);
+
+StatusCode current_sense_main_cycle();
+
+StatusCode current_sense_relay_set(GpioState state);

projects/solar_sense/src/current_sense.c

@@ -0,0 +1,81 @@
+#include "current_sense.h"
+
+#include <stdint.h>
+
+#include "gpio.h"
+#include "i2c.h"
+#include "solar_sense_setters.h"
+#include "status.h"
+
+#define LTC2451_I2C_ADDR 0x14
+
+#define ADC_REFERENCE_VOLTAGE 3.3
+#define ADC_RESOLUTION 65535
+
+#define CURRENT_THRESHOLD 100  // TO-DO: Ask HW team
+#define CURRENT_SENSOR_SENSITIVITY 0.066
+
+static GpioAddress relay_en_address = { GPIO_PORT_B, 4 };      // Enable pin
+static GpioAddress relay_status_address = { GPIO_PORT_A, 6 };  // Status pin
+
+static GpioAddress *relay_en_gpio = &relay_en_address;
+static GpioAddress *relay_status_gpio = &relay_status_address;
+
+static GpioState relay_status;
+
+// LTC2451 ADC Possible conversion speeds
+#define CURRENT_SENSE_ADC_30_HZ 0x80;
+#define CURRENT_SENSE_ADC_60_HZ 0x00;
+
+// Set conversion speed to either 30Hz or 60Hz defined above
+StatusCode current_sense_init(uint8_t conversion_speed) {
+  I2CSettings i2c_settings = {
+    .speed = I2C_SPEED_FAST,
+    .scl = { .port = GPIO_PORT_B, .pin = 8 },
+    .sda = { .port = GPIO_PORT_B, .pin = 9 },
+  };
+
+  status_ok_or_return(i2c_init(I2C_PORT_1, &i2c_settings));
+
+  // Write to the LTC2451 to set conversion speed
+  status_ok_or_return(i2c_write(I2C_PORT_1, LTC2451_I2C_ADDR, &conversion_speed, 1));
+
+  // Initialize GPIOs for relay
+  status_ok_or_return(gpio_init_pin(relay_en_gpio, GPIO_OUTPUT_PUSH_PULL, GPIO_STATE_LOW));
+  status_ok_or_return(gpio_init_pin(relay_status_gpio, GPIO_INPUT_PULL_DOWN, GPIO_STATE_LOW));
+  status_ok_or_return(gpio_set_state(relay_status_gpio, GPIO_STATE_LOW));
+
+  return STATUS_CODE_OK;
+}
+
+// ADC reading and conversion
+StatusCode current_sense_main_cycle() {
+  uint8_t read_bytes[2];
+  status_ok_or_return(i2c_read(I2C_PORT_1, LTC2451_I2C_ADDR, read_bytes, 2));
+
+  // Convert read bytes to single value
+  uint16_t adc_reading = (read_bytes[0] << 8) | read_bytes[1];
+
+  uint16_t voltage_measured = (uint16_t)((ADC_REFERENCE_VOLTAGE * adc_reading) / ADC_RESOLUTION);
+  uint16_t current_measured = (uint16_t)(voltage_measured / CURRENT_SENSOR_SENSITIVITY);
+
+  // Open relay on fault
+  if (current_measured > CURRENT_THRESHOLD) {
+    current_sense_relay_set(GPIO_STATE_HIGH);
+  }
+
+  // Send info to CAN
+  set_current_sense_current(current_measured);
+  set_current_sense_voltage(voltage_measured);
+  set_current_sense_relay_status(relay_status);
+
+  return STATUS_CODE_OK;
+}
+
+// Set state to: GPIO_LOW -> Relay close; GPIO_HIGH -> Relay open
+StatusCode current_sense_relay_set(GpioState state) {
+  status_ok_or_return(gpio_set_state(relay_en_gpio, state));
+  status_ok_or_return(gpio_get_state(relay_status_gpio, &relay_status));
+
+  return STATUS_CODE_OK;
+}