Add ina260 example

This can be used to monitor power usage of a Pico device.

Author: peterharperuk

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(ina260_i2c)
 else()
     message("Skipping I2C examples as hardware_i2c is unavailable on this platform")
 endif()

i2c/ina260_i2c/CMakeLists.txt

@@ -0,0 +1,8 @@
+add_executable(ina260_i2c
+    ina260_i2c.c
+)
+target_link_libraries(ina260_i2c
+    pico_stdlib
+    hardware_i2c
+)
+pico_add_extra_outputs(ina260_i2c)

i2c/ina260_i2c/ina260_i2c.c

@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include "pico/stdlib.h"
+#include "hardware/i2c.h"
+
+#define CURRENT_REGISTER 0x01
+#define VOLTAGE_REGISTER 0x02
+#define POWER_REGISTER 0x03
+#define I2C_ADDRESS 0x40
+
+#define ByteSwap(u)  (uint16_t)((u << 8)|(u >> 8))
+
+// Read register value
+static uint16_t read_reg(uint8_t reg) {
+    // Set the register address
+    int ret = i2c_write_blocking(i2c_default, I2C_ADDRESS, &reg, 1, true); // no stop is set
+    assert(ret == 1);
+    if (ret != 1) return 0;
+    // Read the value
+    uint16_t data;
+    ret = i2c_read_blocking(i2c_default, I2C_ADDRESS, (uint8_t*)&data, 2, false);
+    assert(ret == 2);
+    if (ret != 2) return 0;
+    return ByteSwap(data);
+}
+
+int main() {
+    setup_default_uart();
+    printf("ina260 test\n");
+
+    // Initialise i2c
+    i2c_init(i2c_default, 100 * 1000);
+    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);
+
+    while(true) {
+
+        // Read current and convert to mA
+        float ma = read_reg(CURRENT_REGISTER) * 1.250f;
+        if (ma > 15000) ma = 0;
+        // Read the voltage
+        float v = read_reg(VOLTAGE_REGISTER) * 0.00125f;
+        // Read power and convert to mW
+        uint16_t mw = read_reg(POWER_REGISTER) * 10;
+    
+        // Display results
+        printf("current: %.2f mA voltage: %.2f v power: %u mW\n", ma, v, mw);
+        sleep_ms(1000);
+    }
+    return 0;
+}