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will-v-piwill-v-pi
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Add ina237 and ina219 examples (#770)
* Add ina219 and ina237 examples * Add uart passthrough to ina237 example * Fixup ina260 readme wording
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‎README.md‎

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@@ -152,7 +152,9 @@ App|Description
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---|---
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[bus_scan](i2c/bus_scan) | Scan the I2C bus for devices and display results.
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[bmp280_i2c](i2c/bmp280_i2c) | Read and convert temperature and pressure data from a BMP280 sensor, attached to an I2C bus.
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[ina260_i2c](i2c/ina260_i2c) | Monitor power usage of another Pico device ina260 sensor, via I2C.
155+
[ina219_i2c](i2c/ina219_i2c) | Monitor power usage of another Pico device using an ina219 sensor, via I2C.
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[ina237_i2c](i2c/ina237_i2c) | Monitor power usage of another Pico device using an ina237 sensor, via I2C.
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[ina260_i2c](i2c/ina260_i2c) | Monitor power usage of another Pico device using an ina260 sensor, via I2C.
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[lcd_1602_i2c](i2c/lcd_1602_i2c) | Display some text on a generic 16x2 character LCD display, via I2C.
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[lis3dh_i2c](i2c/lis3dh_i2c) | Read acceleration and temperature value from a LIS3DH sensor via I2C
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[mcp9808_i2c](i2c/mcp9808_i2c) | Read temperature from a MCP9808 sensor, set limits and raise alerts when limits are surpassed.

‎i2c/CMakeLists.txt‎

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@@ -13,6 +13,8 @@ if (TARGET hardware_i2c)
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add_subdirectory_exclude_platforms(ht16k33_i2c)
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add_subdirectory_exclude_platforms(slave_mem_i2c)
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add_subdirectory_exclude_platforms(ina260_i2c)
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add_subdirectory_exclude_platforms(ina219_i2c)
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add_subdirectory_exclude_platforms(ina237_i2c)
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else()
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message("Skipping I2C examples as hardware_i2c is unavailable on this platform")
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endif()

‎i2c/ina219_i2c/CMakeLists.txt‎

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add_executable(ina219_i2c
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ina219_i2c.c
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)
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target_link_libraries(ina219_i2c
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pico_stdlib
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pico_status_led
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hardware_i2c
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)
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# Wait at most 3s for stdio_usb to be ready
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target_compile_definitions(ina219_i2c PRIVATE
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PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS=3000
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)
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pico_add_extra_outputs(ina219_i2c)
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pico_enable_stdio_usb(ina219_i2c 1)
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pico_enable_stdio_uart(ina219_i2c 1)

‎i2c/ina219_i2c/ina219_i2c.c‎

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#include <stdio.h>
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#include "pico/stdlib.h"
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#include "hardware/i2c.h"
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#include "pico/status_led.h"
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#include "pico/binary_info.h"
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#define I2C_ADDRESS 0x40
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// INA219 register addresses
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#define REG_CONFIG 0x00
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#define REG_SHUNTVOLT 0x01
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#define REG_BUSVOLT 0x02
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#define REG_POWER 0x03
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#define REG_CURRENT 0x04
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#define REG_CALIBRATION 0x05
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// CONFIG: 16V bus range, gain ÷1 (±40mV shunt), 12-bit 32-sample averaging, continuous bus+shunt
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// bit13=0 (16V), bits[12:11]=00 (÷1), bits[10:7]=0xD (32S), bits[6:3]=0xD (32S), bits[2:0]=7
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#define CONFIG_VALUE 0x06EFu
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// Calibration for 0.1 Ω shunt resistor (Adafruit INA219 breakout default), 400 mA maximum current
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// CAL = 0.04096 / (current_lsb_A × rshunt) = 0.04096 / (0.0001 × 0.1) = 4096
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#define CALIBRATION_VALUE 4096u
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#define CURRENT_LSB_MA 0.1f // 0.04096 / (4096 × 0.1 Ω) × 1000 mA/LSB
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#define POWER_LSB_MW 2.0f // 20 × CURRENT_LSB_MA mW/LSB
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// Shunt voltage: signed 16-bit, 10 µV/LSB = 0.01 mV/LSB
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// Bus voltage: bits [15:3], 4 mV/LSB; bit 1 = conversion ready, bit 0 = math overflow
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#define VSHUNT_LSB_MV 0.01f
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#define VBUS_LSB_MV 4.0f
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#define BUSVOLT_OVF 0x01u
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static void write_reg(uint8_t reg, uint16_t value) {
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uint8_t buf[3] = { reg, (uint8_t)(value >> 8), (uint8_t)(value & 0xFF) };
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int ret = i2c_write_blocking(i2c_default, I2C_ADDRESS, buf, 3, false);
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assert(ret == 3);
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}
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static uint16_t read_reg(uint8_t reg) {
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int ret = i2c_write_blocking(i2c_default, I2C_ADDRESS, &reg, 1, true);
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assert(ret == 1);
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if (ret != 1) return 0;
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uint8_t buf[2];
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ret = i2c_read_blocking(i2c_default, I2C_ADDRESS, buf, 2, false);
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assert(ret == 2);
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if (ret != 2) return 0;
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return ((uint16_t)buf[0] << 8) | buf[1];
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}
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int main() {
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stdio_init_all();
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#if !defined(i2c_default) || !defined(PICO_DEFAULT_I2C_SDA_PIN) || !defined(PICO_DEFAULT_I2C_SCL_PIN)
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#warning i2c / ina219_i2c example requires a board with I2C pins
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panic("Default I2C pins were not defined");
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#endif
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bi_decl(bi_2pins_with_func(PICO_DEFAULT_I2C_SDA_PIN, PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C));
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bi_decl(bi_program_description("INA219 I2C example for the Raspberry Pi Pico"));
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printf("INA219 example\n");
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i2c_init(i2c_default, 100 * 1000);
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gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C);
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gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C);
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gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN);
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gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN);
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write_reg(REG_CONFIG, CONFIG_VALUE);
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write_reg(REG_CALIBRATION, CALIBRATION_VALUE);
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hard_assert(status_led_init());
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while (true) {
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status_led_set_state(true);
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// Re-write calibration each iteration: a sharp load transient can reset the INA219,
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// clearing the calibration register and making CURRENT and POWER read zero
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write_reg(REG_CALIBRATION, CALIBRATION_VALUE);
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// Shunt voltage: 10 µV/LSB, signed
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float vshunt_mv = (int16_t)read_reg(REG_SHUNTVOLT) * VSHUNT_LSB_MV;
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// Bus voltage: bits [15:3] at 4 mV/LSB; bit 0 is the math overflow flag
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uint16_t bus_raw = read_reg(REG_BUSVOLT);
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float vbus_v = (bus_raw >> 3) * VBUS_LSB_MV / 1000.0f;
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// Current: signed, CURRENT_LSB_MA mA/LSB
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float ma = (int16_t)read_reg(REG_CURRENT) * CURRENT_LSB_MA;
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// Power: unsigned, POWER_LSB_MW mW/LSB
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float mw = read_reg(REG_POWER) * POWER_LSB_MW;
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// INA219 measures on the high side: VIN+ is the supply, VIN- is the load
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float vin_v = vbus_v + vshunt_mv / 1000.0f;
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printf("VIN+: %.3f V VIN-: %.3f V shunt: %.3f mV current: %.2f mA power: %.2f mW\n",
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vin_v, vbus_v, vshunt_mv, ma, mw);
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if (bus_raw & BUSVOLT_OVF) {
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printf("Math overflow - measurement out of range\n");
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}
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status_led_set_state(false);
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sleep_ms(1000);
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}
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return 0;
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}

‎i2c/ina237_i2c/CMakeLists.txt‎

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add_executable(ina237_i2c
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ina237_i2c.c
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)
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target_link_libraries(ina237_i2c
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pico_stdlib
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pico_status_led
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hardware_i2c
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hardware_uart
9+
)
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# Wait at most 3s for stdio_usb to be ready
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target_compile_definitions(ina237_i2c PRIVATE
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PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS=3000
13+
)
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pico_add_extra_outputs(ina237_i2c)
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pico_enable_stdio_usb(ina237_i2c 1)
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pico_enable_stdio_uart(ina237_i2c 1)

‎i2c/ina237_i2c/ina237_i2c.c‎

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#include <stdio.h>
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#include "pico/stdlib.h"
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#include "hardware/i2c.h"
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#include "hardware/uart.h"
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#include "pico/status_led.h"
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#include "pico/binary_info.h"
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#define UART_PASSTHROUGH uart1
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#define UART_PASSTHROUGH_BAUD 115200
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#define UART_PASSTHROUGH_RX 5
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#define I2C_ADDRESS 0x40
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// INA237 register addresses
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#define REG_CONFIG 0x00
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#define REG_ADCCFG 0x01
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#define REG_SHUNTCAL 0x02
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#define REG_VSHUNT 0x04
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#define REG_VBUS 0x05
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#define REG_DIETEMP 0x06
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#define REG_CURRENT 0x07
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#define REG_POWER 0x08
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#define REG_DIAG 0x0B
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// Calibration for 15 mΩ shunt resistor (Adafruit INA237 breakout default), 250 mA maximum expected current
26+
#define SHUNT_RES_OHMS 0.015f
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#define MAX_CURRENT_A 0.25f
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#define CURRENT_LSB_A (MAX_CURRENT_A / 32768.0f)
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// SHUNT_CAL = 819.2e6 × CURRENT_LSB × RSHUNT × 4 (ADC range 1, scale = 4)
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#define SHUNT_CAL_VALUE ((uint16_t)(819.2e6f * CURRENT_LSB_A * SHUNT_RES_OHMS * 4))
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// ADCCFG: triggered temp+bus+shunt (mode=0x7); 1052 µs conversion time for bus, shunt & temp (=0x5); 16 sample average (=0x2)
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// bits [15:12]=0xF, bits [11:9]=0x5, bits [8:6]=0x5, bits [5:3]=0x5, bits [2:0]=0x2
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#define ADCCFG_VALUE 0x7B6Au
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static void write_reg(uint8_t reg, uint16_t value) {
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uint8_t buf[3] = { reg, (uint8_t)(value >> 8), (uint8_t)(value & 0xFF) };
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int ret = i2c_write_blocking(i2c_default, I2C_ADDRESS, buf, 3, false);
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assert(ret == 3);
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}
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// Read 16-bit register (the usual)
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static uint16_t read_reg(uint8_t reg) {
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int ret = i2c_write_blocking(i2c_default, I2C_ADDRESS, &reg, 1, true);
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assert(ret == 1);
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if (ret != 1) return 0;
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uint8_t buf[2];
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ret = i2c_read_blocking(i2c_default, I2C_ADDRESS, buf, 2, false);
49+
assert(ret == 2);
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if (ret != 2) return 0;
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return ((uint16_t)buf[0] << 8) | buf[1];
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}
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// Read 24-bit register (the power register)
55+
static uint32_t read_reg3(uint8_t reg) {
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int ret = i2c_write_blocking(i2c_default, I2C_ADDRESS, &reg, 1, true);
57+
assert(ret == 1);
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if (ret != 1) return 0;
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uint8_t buf[3];
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ret = i2c_read_blocking(i2c_default, I2C_ADDRESS, buf, 3, false);
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assert(ret == 3);
62+
if (ret != 3) return 0;
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return ((uint32_t)buf[0] << 16) | ((uint32_t)buf[1] << 8) | buf[2];
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}
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static void print_uart_passthrough(void) {
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// Interrupts will go off until the uart is read, so disable them
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uart_set_irqs_enabled(UART_PASSTHROUGH, false, false);
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while (uart_is_readable(UART_PASSTHROUGH))
70+
putchar(uart_getc(UART_PASSTHROUGH));
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uart_set_irqs_enabled(UART_PASSTHROUGH, true, false);
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}
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int main() {
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stdio_init_all();
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#if !defined(i2c_default) || !defined(PICO_DEFAULT_I2C_SDA_PIN) || !defined(PICO_DEFAULT_I2C_SCL_PIN)
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#warning i2c / ina237_i2c example requires a board with I2C pins
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panic("Default I2C pins were not defined");
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#endif
80+
bi_decl(bi_2pins_with_func(PICO_DEFAULT_I2C_SDA_PIN, PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C));
81+
bi_decl(bi_1pin_with_func(UART_PASSTHROUGH_RX, GPIO_FUNC_UART));
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bi_decl(bi_program_description("INA237 I2C example for the Raspberry Pi Pico"));
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printf("INA237 example\n");
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uart_init(UART_PASSTHROUGH, UART_PASSTHROUGH_BAUD);
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gpio_set_function(UART_PASSTHROUGH_RX, GPIO_FUNC_UART);
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uint irq_num = UART_IRQ_NUM(UART_PASSTHROUGH);
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irq_set_exclusive_handler(irq_num, print_uart_passthrough);
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irq_set_enabled(irq_num, true);
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uart_set_irqs_enabled(UART_PASSTHROUGH, true, false);
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i2c_init(i2c_default, 100 * 1000);
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gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C);
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gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C);
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gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN);
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gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN);
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// Set ADC range 1: ±40.96 mV full scale (bit 4 of CONFIG), giving 1.25 µV/LSB shunt resolution
101+
write_reg(REG_CONFIG, 0x0010u);
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// Write shunt calibration so that CURRENT and POWER registers are scaled correctly
103+
write_reg(REG_SHUNTCAL, SHUNT_CAL_VALUE);
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hard_assert(status_led_init());
106+
while (true) {
107+
status_led_set_state(true);
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// Trigger single conversion of bus voltage, shunt voltage and temperature
110+
// This ensures all the values will correspond to the same measurement
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write_reg(REG_ADCCFG, ADCCFG_VALUE);
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// Wait for conversion ready
114+
while (!(read_reg(REG_DIAG) & (1 << 1))) tight_loop_contents();
115+
116+
// Bus voltage: 3.125 mV/LSB, unsigned
117+
float v = read_reg(REG_VBUS) * 0.003125f;
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// Shunt voltage: 1.25 µV/LSB (ADC range 1, ±40.96 mV full scale), signed
120+
float vshunt_mv = (int16_t)read_reg(REG_VSHUNT) * 1.25f / 1000.0f;
121+
122+
// Current: CURRENT_LSB A/LSB, signed
123+
float ma = (int16_t)read_reg(REG_CURRENT) * CURRENT_LSB_A * 1000.0f;
124+
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// Power: 20 × CURRENT_LSB W/LSB, unsigned
126+
float mw = read_reg3(REG_POWER) * 0.2f * CURRENT_LSB_A * 1000.0f;
127+
128+
float mw_calc = v * ma;
129+
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// Die temperature: bits [15:4] are the 12-bit signed value, 125 m°C/LSB
131+
float temp_c = ((int16_t)read_reg(REG_DIETEMP) >> 4) * 0.125f;
132+
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printf("bus: %.3f V shunt: %.3f mV current: %.2f mA power: %.2f mW (calc: %.2f mW) temp: %.2f C\n",
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v, vshunt_mv, ma, mw, mw_calc, temp_c);
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136+
status_led_set_state(false);
137+
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// Wait 1s before taking next measurement
139+
sleep_ms(1000);
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}
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return 0;
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}

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