1 files changed, 50 insertions, 0 deletions
diff --git a/src/altimeter.cpp b/src/altimeter.cpp
new file mode 100644
index 0000000..a5c8849
--- /dev/null
+++ b/src/altimeter.cpp
@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+#include "hardware/gpio.h"
+#include "boards/pico_w.h"
+#include "hardware/i2c.h"
+#include "pico/stdio.h"
+#include "pico/time.h"
+
+#define ALT_ADDR 0x60
+#define MAX_SCL 400000
+#define DATA_RATE_HZ 15
+
+float altitude = 0.0f;
+float get_altitude();
+
+int main() {
+    stdio_init_all();
+
+    i2c_init(i2c_default, MAX_SCL);
+    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);
+
+    uint8_t config[2] = {0};
+
+    // Select control register(0x26)
+    // Active mode, OSR = 16, altimeter mode(0xB8)
+    config[0] = 0x26;
+    config[1] = 0xB9;
+    i2c_write_blocking(i2c_default, ALT_ADDR, config, 2, true);
+    sleep_ms(1500);
+
+    while (1) {
+        sleep_ms(1000);
+        altitude = get_altitude();
+        printf("Altitude: %4.2f\n", altitude);
+    }
+}
+
+float get_altitude() {
+    uint8_t reg = 0x01;
+    uint8_t data[5];
+    i2c_write_blocking(i2c_default, ALT_ADDR, &reg, 1, true);
+    i2c_read_blocking(i2c_default, ALT_ADDR, data, 5, false);
+    // Exactly how MPL3115A2 datasheet says to retrieve altitude
+    float altitude = (float) ((int16_t) ((data[0] << 8) | data[1])) + (float) (data[2] >> 4) * 0.0625;
+    return altitude;
+}
+