Example measuring ADS1219 with I2C

examples/tests/ads1219/Makefile

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+# Makefile for user application
+
+# Specify this directory relative to the current application.
+TOCK_USERLAND_BASE_DIR = ../../..
+
+# Which files to compile.
+C_SRCS := main.c ads1219.c
+
+STACK_SIZE := 2048
+
+# Include userland master makefile. Contains rules and flags for actually
+# building the application.
+include $(TOCK_USERLAND_BASE_DIR)/AppMakefile.mk

examples/tests/ads1219/README.md

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+# ADS1219 Testing
+
+The ADS1219 is the external ADC used on the ENTS board for high fidelity analog measurements. This tests the basic functionality of the ADS1219 using the userspace I2C driver.

examples/tests/ads1219/ads1219.c

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+/**
+ * @file    ads.c
+ * @author  Stephen Taylor
+ * @brief   Soil Power Sensor ADS12 library
+ * @date    11/27/2023
+ *
+ * This file provides a function to read from the ADS1219.
+ *
+ * This file was copied and modified from the ENTS libraries.
+ *
+ * TODO (jmadden173): Add support for data ready pin
+ * TODO (jmadden173): Improve lib with big bang for regs
+ * TODO (jmadden173): Add offset calibration at startup
+ **/
+
+#include "ads1219.h"
+
+#include <libtock/tock.h>
+#include <libtock-sync/services/alarm.h>
+#include <libtock/peripherals/i2c_master.h>
+
+
+// Generic calibration values that give rough estimate
+static const double voltage_calibration_m = -0.00039326;
+static const double voltage_calibration_b = 4.92916378e-05;
+static const double current_calibration_m = -1.18693164e-10;
+static const double current_calibration_b = 4.14518594e-05;
+
+static const uint8_t addr = 0x40;
+/** i2c address left shifted one bit for hal i2c funcs */
+static uint8_t addrls = addr << 1;
+
+/** i2c address */
+typedef enum {
+  /** Reset the device */
+  cmd_reset = 0x06,
+  /** Start or restart conversion */
+  cmd_start = 0x08,
+  /** Enter power-down mode */
+  cmd_powerdown = 0x02,
+  /** Read data */
+  cmd_rdata = 0x10,
+  /** Write to register */
+  // prev 0x80
+  cmd_rreg = 0x20,
+  /** Read from register */
+  cmd_wreg = 0x40
+} ads1219_cmd_t;
+
+/**
+ * Control register breakdown.
+ *
+ * The implementation for the bit field uses the first value as the LSB. Aka
+ * vref is the LSB and mux is the MSB.
+ *
+ *  7:5 MUX (default)
+ *  4   Gain (default)
+ *  3:2 Data rate (default)
+ *  1   Conversion mode (default)
+ *  0   VREF (External reference 3.3V)
+ */
+typedef union {
+  uint8_t value;
+  struct {
+    uint8_t vref : 1;
+    uint8_t mode : 1;
+    uint8_t dr : 2;
+    uint8_t gain : 1;
+    uint8_t mux : 3;
+  } bits;
+} ConfigReg;
+
+/**
+ * @brief GPIO port for adc data ready line
+ *
+ * @see data_ready_pin
+ */
+//const GPIO_TypeDef *data_ready_port = GPIOC;
+
+/**
+ * @brief GPIO pin for adc data ready line
+ *
+ */
+//const uint16_t data_ready_pin = GPIO_PIN_0;
+
+/**
+ * @brief Turn on power to analog circuit
+ *
+ * Has a blocking wait of 1 mS to account for the startup time of OpAmps. This
+ * should be an order of magnitude greater than the startup or turn-on time of
+ * the opamps used in the circuit.
+ *
+ * MAX9944 - N/A
+ * INA296 - 20 uS
+ * THS4532 - 420 nS
+ *
+ * @see data_ready_pin
+ */
+void power_on(void);
+
+/**
+ * @brief Turn off power to analog circuit
+ *
+ * @see data_ready_pin
+ */
+void power_off(void);
+
+/**
+ * @brief Measure from the adc
+ *
+ * @param mwas Raw measurement
+ *
+ * @return Raw measurement from adc
+ */
+ads1219_status_t measure(uint32_t *meas);
+
+/**
+ * @brief This function reconfigures the ADS1219 based on the parameter reg_data
+ *
+ * @param reg_data
+ * @return ads1219_status_t
+ */
+ads1219_status_t configure(const ConfigReg reg_data);
+
+ads1219_status_t ads1219_reset(void) {
+  int ret = RETURNCODE_SUCCESS;
+
+  // Send the reset code
+  uint8_t write_buf[1] = {cmd_reset};
+  ret = i2c_master_write_sync(addrls, write_buf, 1);
+  if (ret != RETURNCODE_SUCCESS) {
+    return ADS1219_ERROR;
+  }
+
+  // wait minimum 500 us to reach steady state
+  libtocksync_alarm_delay_ms(1);
+
+  return ADS1219_SUCCESS;
+}
+
+ads1219_status_t configure(const ConfigReg reg_data) {
+  int ret = RETURNCODE_SUCCESS;
+  uint8_t i2c_data[2] = {cmd_wreg, reg_data.value};
+  ret = i2c_master_write_sync(addrls, (uint8_t *)i2c_data, sizeof(i2c_data));
+  if (ret != RETURNCODE_SUCCESS) {
+    return ADS1219_CONFIGURE;
+  }
+
+  return ADS1219_SUCCESS;
+}
+
+ads1219_status_t ads1219_voltage_raw(uint32_t *voltage) {
+  ads1219_status_t ret = ADS1219_SUCCESS;
+
+  ConfigReg reg_data = {0};
+  reg_data.bits.vref = 1;
+
+  // 0x21 is single shot and 0x23 is continuos
+  // configure to read voltage
+  ret = configure(reg_data);
+  if (ret != ADS1219_SUCCESS) {
+    return ret;
+  }
+
+  ret = measure(voltage);
+  if (ret != ADS1219_SUCCESS) {
+    return ret;
+  }
+
+  return ret;
+}
+
+ads1219_status_t ads1219_voltage(double *voltage) {
+  ads1219_status_t ret = ADS1219_SUCCESS;
+
+  uint32_t raw = 0;
+  ret = ads1219_voltage_raw(&raw);
+
+  *voltage = (voltage_calibration_m * (double) raw) + voltage_calibration_b;
+  *voltage /= 1000;
+
+  return ret;
+}
+
+ads1219_status_t ads1219_current_raw(uint32_t *current) {
+  ads1219_status_t ret = ADS1219_SUCCESS;
+  double meas = 0.0;
+
+  ConfigReg reg_data = {0};
+  reg_data.bits.mux = 0b001;
+  reg_data.bits.vref = 1;
+
+  // 0x21 is single shot and 0x23 is continuos
+  // configure to read voltage
+  ret = configure(reg_data);
+  if (ret != ADS1219_SUCCESS) {
+    return -1;
+  }
+
+  ret = measure(current);
+  if (ret != ADS1219_SUCCESS) {
+    return -1;
+  }
+
+  return meas;
+}
+
+ads1219_status_t ads1219_current(double *current) {
+  ads1219_status_t ret = ADS1219_SUCCESS;
+
+  uint32_t raw = 0;
+  ret = ads1219_current_raw(&raw);
+
+  *current = (current_calibration_m * (double) raw) + current_calibration_b;
+  return ret; 
+}
+
+void power_on(void) {
+  //// set high
+  //HAL_GPIO_WritePin(POWERDOWN_GPIO_Port, POWERDOWN_Pin, GPIO_PIN_SET);
+  //// delay for settling of analog components
+  //HAL_Delay(1);
+}
+
+void power_off(void) {
+  //// set low
+  //HAL_GPIO_WritePin(POWERDOWN_GPIO_Port, POWERDOWN_Pin, GPIO_PIN_RESET);
+}
+
+ads1219_status_t measure(uint32_t *meas) {
+  int ret = RETURNCODE_SUCCESS;
+
+  uint8_t rx_data[3] = {0x00, 0x00, 0x00};
+
+  power_on();
+
+  // start conversion
+  uint8_t buf[1] = {cmd_start};
+  ret = i2c_master_write_sync(addrls, buf, 1);
+  if (ret != RETURNCODE_SUCCESS) {
+    return ADS1219_CONVERSION;
+  }
+
+  // constant delay
+  libtocksync_alarm_delay_ms(100);
+
+  // TODO(jmadden173) implement data ready pin wait
+  // Wait for the DRDY pin on the ADS12 to go low, this means data is ready
+  //while (HAL_GPIO_ReadPin(data_ready_port, data_ready_pin)) {}
+
+  // send read data command
+  buf[0] = cmd_rdata;
+  ret = i2c_master_write_sync(addrls, buf, 1);
+  if (ret != RETURNCODE_SUCCESS) {
+    return ADS1219_MEASURE;
+  }
+
+  // read 3 bytes of data
+  ret = i2c_master_read_sync(addrls, rx_data, 3);
+  if (ret != RETURNCODE_SUCCESS) {
+    return ADS1219_MEASURE;
+  }
+
+  power_off();
+
+  // Combine the 3 bytes into a 24-bit value
+  *meas = ((int32_t)rx_data[0] << 16) | ((int32_t)rx_data[1] << 8) |
+          ((int32_t)rx_data[2]);
+  // Check if the sign bit (24th bit) is set
+  if (*meas & 0x800000) {
+    // Extend the sign to 32 bits
+    *meas |= 0xFF000000;
+  }
+
+  return ADS1219_SUCCESS;
+}

examples/tests/ads1219/ads1219.h

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+/**
+ ******************************************************************************
+ * @file     ads1219.h
+ * @author   Stephen Taylor
+ * @brief    This file contains all the function prototypes for
+ *           the ads.c file
+ * @date     11/27/2023
+ *
+ *
+ * This file was copied and modified from the ENTS libraries
+ ******************************************************************************
+ * Copyright [2023] <Stephen Taylor>
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdio.h>
+#include <stdint.h>
+
+/**
+ * @ingroup stm32
+ * @defgroup ads ADS1219
+ * @brief Library for interfacing with the ADS1219 ADC
+ *
+ * This library is designed to read measurements from the ADS1219 ADC. When not
+ * actively taking measurements, the analog frontend is power down to reduce
+ * parasitic current.
+ *
+ * Library expected I2C and GPIO to be initialized before use.
+ *
+ * Example: @ref example_adc.c
+ *
+ * Datasheet: https://www.ti.com/product/ADS1219
+ *
+ *
+ * @{
+ */
+
+typedef enum {
+  ADS1219_SUCCESS,
+  ADS1219_ERROR = -1,
+  ADS1219_CONFIGURE = -2,
+  ADS1219_MEASURE = -3,
+  ADS1219_CONVERSION = -4
+} ads1219_status_t;
+
+
+/**
+******************************************************************************
+* @brief    This function starts up the ADS1219
+*
+*           This function is a wrapper for the STM32 HAl I2C library. The
+*ADS1219 uses I2C the I2C communication protocol. This function configures then
+*ADS1219 for single read mode. Note: the ADS1219 requires a minimum of 500us
+*when it is powered on.
+*
+* @param    void
+* @return   HAL_StatusTypeDef
+********************************************\n**********************************
+*/
+ads1219_status_t ads1219_reset(void);
+
+/**
+******************************************************************************
+* @brief    This function reads the current ADC voltage value.
+*
+*           This function is a wrapper for the STM32 HAl I2C library. The
+*ADS1219 uses I2C the I2C communication protocol. This version simply chops the
+*noisy bits.
+*
+* @param    void
+* @return   double, current ADC reading in microvolts
+******************************************************************************
+*/
+ads1219_status_t ads1219_voltage(double *voltage);
+ads1219_status_t ads1219_voltage_raw(uint32_t *voltage);
+
+/**
+******************************************************************************
+* @brief    This function reads the current ADC ampere value.
+*
+*           This function is a wrapper for the STM32 HAl I2C library. The
+*ADS1219 uses I2C the I2C communication protocol. This version simply chops the
+*noisy bits.
+*
+* @param    void
+* @return   double, current ADC reading in microamps
+******************************************************************************
+*/
+ads1219_status_t ads1219_current(double *current);
+ads1219_status_t ads1219_current_raw(uint32_t *current);
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif