Added ina228 example

README.md

@@ -159,6 +159,7 @@ App|Description
 [ht16k33_i2c](i2c/ht16k33_i2c) | Drive a 4 digit 14 segment LED with an HT16K33.
 [slave_mem_i2c](i2c/slave_mem_i2c) | i2c slave example where the slave implements a 256 byte memory.
 [slave_mem_i2c_burst](i2c/slave_mem_i2c) | i2c slave example where the slave implements a 256 byte memory. This version inefficiently writes each byte in a separate call to demonstrate read and write burst mode.
+[ina228_i2c](i2c/ina228) | Read voltage, current, temperature, power, energy and charge from INA228 sensor, via I2C.
 
 ### Interpolator
 

i2c/CMakeLists.txt

@@ -12,6 +12,7 @@ if (TARGET hardware_i2c)
     add_subdirectory_exclude_platforms(pcf8523_i2c)
     add_subdirectory_exclude_platforms(ht16k33_i2c)
     add_subdirectory_exclude_platforms(slave_mem_i2c)
+    add_subdirectory_exclude_platforms(ina228_i2c)
 else()
     message("Skipping I2C examples as hardware_i2c is unavailable on this platform")
 endif()

i2c/ina228_i2c/CMakeLists.txt

@@ -0,0 +1,13 @@
+add_executable(ina228_i2c ina228_i2c.c)
+
+# pull in common dependencies and additional i2c hardware support
+target_link_libraries(ina228_i2c
+        pico_stdlib
+        hardware_i2c)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(ina228_i2c)
+
+# add url via pico_set_program_url
+example_auto_set_url(ina228_i2c)
+

i2c/ina228_i2c/README.adoc

@@ -0,0 +1,37 @@
+= Reading an INA228 power sensor via I2C
+
+This example code shows how to interface the Raspberry Pi Pico with the INA228 current/voltage/power/temperature/energy/charge sensor. The sensor features a 20-bit ADC and supports up to 85V DC, making it a great choice for high precision measurements. It is capable of high-side and low-side measurements (which can be configured by soldering the jumper on the back of the board), but this example focuses on low-side measurements.
+
+The sensor breakout board has an integrated 0.015 ohm, high precision shunt resistor, which is used for measuring voltage drop, which also gives current since the resistor value is known. This current, combined with the load voltage, allows load power and energy to be calculated. This example measures the power consumption of an LED.
+
+[TIP]
+======
+The INA228 is highly configurable. Find the datasheet online (https://www.ti.com/lit/ds/symlink/ina228.pdf) to explore all of its capabilities beyond the simple example given here.
+======
+
+== Wiring information
+
+[[ina228_i2c_wiring]]
+[pdfwidth=75%]
+.Wiring Diagram for INA228 sensor via I2C.
+image::ina228_i2c.png[]
+
+== List of Files
+
+CMakeLists.txt:: CMake file to incorporate the example into the examples build tree.
+ina228_i2c.c:: The example code.
+
+== Bill of Materials
+
+.A list of materials required for the example
+[[ina228_i2c-bom-table]]
+[cols=3]
+|===
+| *Item* | *Quantity* | Details
+| Breadboard | 1 | generic part
+| Raspberry Pi Pico (any) | 1 | https://www.raspberrypi.com/products/raspberry-pi-pico-2/
+| INA228-based breakout board | 1 | https://www.adafruit.com/product/5832
+| M/M Jumper wires | 8 | generic part
+| LED | 1 | generic part
+| 330 ohm resistor | 1 | generic part
+|===

i2c/ina228_i2c/ina228_i2c.c

@@ -0,0 +1,125 @@
+#include <stdio.h>
+#include "pico/stdlib.h"
+#include "hardware/i2c.h"
+#include <math.h>
+
+// LED GPIO
+#define EXT_LED_GPIO 2
+
+// INA228 breakout board shunt resistance in Ohms
+#define R_SHUNT 0.015
+
+// Max expected current through shunt resistor in Amps
+#define MAX_EXPECTED_CURRENT 0.1
+#define I2C_ADDR 0x40
+
+// Macros for converting arrays of bytes to decimal integer
+#define COALESCE_2_BYTES(a2) ((a2[0] << 8) | a2[1])
+#define COALESCE_3_BYTES(a3) ((a3[0] << 16) | (a3[1] << 8) | a3[2])
+#define COALESCE_RESERVED_3_BYTES(a3) ((a3[0] << 12) | (a3[1] << 4) | (a3[2] >> 4))
+#define COALESCE_5_BYTES(a5) (((uint64_t)a5[0] << 32) | (a5[1] << 24) | (a5[2] << 16) | (a5[3] << 8) | a5[4])
+
+// ina228 registers (see datasheet)
+uint8_t VSHUNT_REG = 0x04;
+uint8_t VBUS_REG = 0x05;
+uint8_t DIETEMP_REG = 0x06;
+uint8_t CURRENT_REG = 0x07;
+uint8_t POWER_REG = 0x08;
+uint8_t ENERGY_REG = 0x09;
+uint8_t CHARGE_REG = 0x0A;
+
+uint8_t ADC_CONFIG_REG = 0x01;
+uint8_t SHUNT_CAL_REG = 0x02;
+
+// conversion factors (see datasheet)
+// note: VSHUNT_FACTOR assumes ADCRANGE = 0 
+const double VSHUNT_FACTOR = 312.5 * 1e-9;
+const double VBUS_FACTOR = 195.3125 * 1e-6;
+const double DIETEMP_FACTOR  = 7.8125 * 1e-3;
+const double CURRENT_FACTOR = MAX_EXPECTED_CURRENT / (1<<19);
+const double POWER_FACTOR = 3.2 * CURRENT_FACTOR ;
+const double ENERGY_FACTOR  = 16 * 3.2 * CURRENT_FACTOR;
+const double CHARGE_FACTOR = CURRENT_FACTOR;
+
+const uint16_t SHUNT_CAL = 13107.2 * 1e6 * CURRENT_FACTOR * R_SHUNT;
+
+float vshunt, vbus, dietemp, current, power, energy, charge;
+
+static void ina228_init() {
+    // Write to shunt register 
+    uint8_t shunt_msb = (SHUNT_CAL >> 8) & 0xFF;
+    uint8_t shunt_lsb = SHUNT_CAL & 0xFF;
+    uint8_t shunt_buf[3] = {SHUNT_CAL_REG, shunt_msb, shunt_lsb};
+    i2c_write_blocking(i2c_default, I2C_ADDR, shunt_buf, 3, false);
+
+    // Write to ADC config register (need to enable continuous mode to access accumulation variables energy and charge)
+    uint8_t adc_msb = 0xF0;
+    uint8_t adc_lsb = 0x00;
+    uint8_t adc_buf[3] = {ADC_CONFIG_REG, adc_msb, adc_lsb};
+    i2c_write_blocking(i2c_default, I2C_ADDR, adc_buf, 3, false);
+}
+
+static void ina228_read(float *vshunt, float *vbus, float *dietemp, float *current, float *power, float *energy, float *charge) {
+    // Buffers for writing register measurements to
+    // Some registers are 2 bytes, some are 3 bytes, the accumulation registers are 5 bytes
+    uint8_t buffer_2[2];
+    uint8_t buffer_3[3];
+    uint8_t buffer_5[5];
+
+    // For the vshunt, vbus and current registers the 4 least significant bits are reserved and always read zero, so use variant of coalesce macro to extract value
+    i2c_write_blocking(i2c_default, I2C_ADDR, &VSHUNT_REG, 1, true);
+    i2c_read_blocking(i2c_default, I2C_ADDR, buffer_3, 3, false);
+    *vshunt = COALESCE_RESERVED_3_BYTES(buffer_3) * VSHUNT_FACTOR;
+
+    i2c_write_blocking(i2c_default, I2C_ADDR, &VBUS_REG, 1, true);
+    i2c_read_blocking(i2c_default, I2C_ADDR, buffer_3, 3, false);
+    *vbus = COALESCE_RESERVED_3_BYTES(buffer_3) * VBUS_FACTOR;
+
+    i2c_write_blocking(i2c_default, I2C_ADDR, &DIETEMP_REG, 1, true);
+    i2c_read_blocking(i2c_default, I2C_ADDR, buffer_2, 2, false);
+    *dietemp = COALESCE_2_BYTES(buffer_2) * DIETEMP_FACTOR;
+
+    i2c_write_blocking(i2c_default, I2C_ADDR, &CURRENT_REG, 1, true);
+    i2c_read_blocking(i2c_default, I2C_ADDR, buffer_3, 3, false);
+    *current = COALESCE_RESERVED_3_BYTES(buffer_3) * CURRENT_FACTOR;
+
+    i2c_write_blocking(i2c_default, I2C_ADDR, &POWER_REG, 1, true);
+    i2c_read_blocking(i2c_default, I2C_ADDR, buffer_3, 3, false);
+    *power = COALESCE_3_BYTES(buffer_3) * POWER_FACTOR;
+
+    i2c_write_blocking(i2c_default, I2C_ADDR, &ENERGY_REG, 1, true);
+    i2c_read_blocking(i2c_default, I2C_ADDR, buffer_5, 5, false);
+    *energy = COALESCE_5_BYTES(buffer_5) * ENERGY_FACTOR;
+
+    i2c_write_blocking(i2c_default, I2C_ADDR, &CHARGE_REG, 1, true);
+    i2c_read_blocking(i2c_default, I2C_ADDR, buffer_5, 5, false);
+    *charge = COALESCE_5_BYTES(buffer_5) * CHARGE_FACTOR;
+}
+
+int main()
+{
+    stdio_init_all();
+
+    // Initialise external LED and turn it on (so we can measure some current)
+    gpio_init(EXT_LED_GPIO);
+    gpio_set_dir(EXT_LED_GPIO, GPIO_OUT);
+    gpio_put(EXT_LED_GPIO, true);
+
+    // I2C initialisation
+    i2c_init(i2c_default, 400*1000);
+
+    // GPIO initialisation
+    gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C);
+    gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C);
+    gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN);
+    gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN);
+
+    // Initialise ina228
+    ina228_init();
+
+    while (true) {
+        ina228_read(&vshunt, &vbus, &dietemp, &current, &power, &energy, &charge);
+        printf("INA228 Measurements:\nVSHUNT: %f V\nVBUS: %f V\nDIETEMP: %f °C\nCURRENT: %f A\nPOWER: %f W\nENERGY: %f J\nCHARGE: %f C\n-----------------\n", vshunt, vbus, dietemp, current, power, energy, charge);
+        sleep_ms(1000);
+    }
+}