111 lines
3.6 KiB
C
111 lines
3.6 KiB
C
/**
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdio.h>
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#include <string.h>
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#include "pico/stdlib.h"
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#include "hardware/i2c.h"
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/* Example code to talk to a MPU6050 MEMS accelerometer and gyroscope
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This is taking to simple approach of simply reading registers. It's perfectly
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possible to link up an interrupt line and set things up to read from the
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inbuilt FIFO to make it more useful.
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NOTE: Ensure the device is capable of being driven at 3.3v NOT 5v. The Pico
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GPIO (and therefor I2C) cannot be used at 5v.
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You will need to use a level shifter on the I2C lines if you want to run the
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board at 5v.
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Connections on Raspberry Pi Pico board, other boards may vary.
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GPIO 4 (pin 6)-> SDA on MPU6050 board
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GPIO 5 (pin 7)-> SCL on MPU6050 board
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3.3v (pin 36) -> VCC on MPU6050 board
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GND (pin 38) -> GND on MPU6050 board
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*/
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// By default these devices are on bus address 0x68
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static int addr = 0x68;
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#define I2C_PORT i2c0
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static void mpu6050_reset() {
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// Two byte reset. First byte register, second byte data
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// There are a load more options to set up the device in different ways that could be added here
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uint8_t buf[] = {0x6B, 0x00};
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i2c_write_blocking(I2C_PORT, addr, buf, 2, false);
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}
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static void mpu6050_read_raw(int16_t accel[3], int16_t gyro[3], int16_t *temp) {
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// For this particular device, we send the device the register we want to read
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// first, then subsequently read from the device. The register is auto incrementing
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// so we don't need to keep sending the register we want, just the first.
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uint8_t buffer[6];
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// Start reading acceleration registers from register 0x3B for 6 bytes
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uint8_t val = 0x3B;
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i2c_write_blocking(I2C_PORT, addr, &val, 1, true); // true to keep master control of bus
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i2c_read_blocking(I2C_PORT, addr, buffer, 6, false);
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for (int i = 0; i < 3; i++) {
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accel[i] = (buffer[i * 2] << 8 | buffer[(i * 2) + 1]);
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}
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// Now gyro data from reg 0x43 for 6 bytes
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// The register is auto incrementing on each read
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val = 0x43;
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i2c_write_blocking(I2C_PORT, addr, &val, 1, true);
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i2c_read_blocking(I2C_PORT, addr, buffer, 6, false); // False - finished with bus
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for (int i = 0; i < 3; i++) {
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gyro[i] = (buffer[i * 2] << 8 | buffer[(i * 2) + 1]);;
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}
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// Now temperature from reg 0x41 for 2 bytes
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// The register is auto incrementing on each read
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val = 0x41;
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i2c_write_blocking(I2C_PORT, addr, &val, 1, true);
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i2c_read_blocking(I2C_PORT, addr, buffer, 2, false); // False - finished with bus
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*temp = buffer[0] << 8 | buffer[1];
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}
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int main() {
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stdio_init_all();
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printf("Hello, MPU6050! Reading raw data from registers...\n");
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// This example will use I2C0 on GPIO4 (SDA) and GPIO5 (SCL) running at 400kHz.
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i2c_init(I2C_PORT, 400 * 1000);
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gpio_set_function(4, GPIO_FUNC_I2C);
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gpio_set_function(5, GPIO_FUNC_I2C);
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gpio_pull_up(4);
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gpio_pull_up(5);
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mpu6050_reset();
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int16_t acceleration[3], gyro[3], temp;
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while (1) {
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mpu6050_read_raw(acceleration, gyro, &temp);
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// These are the raw numbers from the chip, so will need tweaking to be really useful.
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// See the datasheet for more information
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printf("Acc. X = %d, Y = %d, Z = %d\n", acceleration[0], acceleration[1], acceleration[2]);
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printf("Gyro. X = %d, Y = %d, Z = %d\n", gyro[0], gyro[1], gyro[2]);
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// Temperature is simple so use the datasheet calculation to get deg C.
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// Note this is chip temperature.
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printf("Temp. = %f\n", (temp / 340.0) + 36.53);
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sleep_ms(100);
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}
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return 0;
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}
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