MPU9250 with STM32: Magnetometer readings are constant #472
Comments
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I can;t debug your code. There are at least two things you need to do to
get mag data out of the AK8963C besides reading the data sheet.
1) set the measurement mode to continuous
2) make sure you read the status register after the data registers,
otherwise the data will never update.
…On Fri, Jan 7, 2022 at 4:28 AM Ibrahim Ozdemir ***@***.***> wrote:
Hi kriswiner,
I'm trying to implement the code you wrote for MPU9250BasicAHRS on my
STM32 based Nucleo card. However, the magnetometer values are constantly
being read.
I think that the magnetometer's power setting may have been stuck in
read-once mode or off mode. I'm sharing my code, I would be very happy if
you can help.
`
/* USER CODE END Header
*/ /* Includes
------------------------------------------------------------------*/
#include "main.h"
#include "i2c.h"
#include "usart.h"
#include "gpio.h"
/* Private includes
----------------------------------------------------------
*/ /* USER CODE BEGIN Includes
*/ #include <stdio.h> #include <math.h> /* USER CODE END Includes */
/* Private typedef
-----------------------------------------------------------
*/ /* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define
------------------------------------------------------------
*/ /* USER CODE BEGIN PD */
//Magnetometer Registers
#define AK8963_ADDRESS 0x0C<<1
#define AK8963_WHO_AM_I 0x00 // should return 0x48
#define AK8963_INFO 0x01
#define AK8963_ST1 0x02 // data ready status bit 0
#define AK8963_XOUT_L 0x03 // data
#define AK8963_XOUT_H 0x04
#define AK8963_YOUT_L 0x05
#define AK8963_YOUT_H 0x06
#define AK8963_ZOUT_L 0x07
#define AK8963_ZOUT_H 0x08
#define AK8963_ST2 0x09 // Data overflow bit 3 and data read error status
bit 2
#define AK8963_CNTL 0x0A // Power down (0000), single-measurement (0001),
self-test (1000) and Fuse ROM (1111) modes on bits 3:0
#define AK8963_ASTC 0x0C // Self test control
#define AK8963_I2CDIS 0x0F // I2C disable
#define AK8963_ASAX 0x10 // Fuse ROM x-axis sensitivity adjustment value
#define AK8963_ASAY 0x11 // Fuse ROM y-axis sensitivity adjustment value
#define AK8963_ASAZ 0x12 // Fuse ROM z-axis sensitivity adjustment value
#define WHO_AM_I_MPU9250 0x75 // Should return 0x71
#define MPU9250_ADDRESS 0x68<<1
#define INT_PIN_CFG 0x37
/* USER CODE END PD */
/* Private macro
-------------------------------------------------------------
*/ /* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables
---------------------------------------------------------*/
/* USER CODE BEGIN PV */
enum Mscale {
MFS_14BITS = 0, // 0.6 mG per LSB
MFS_16BITS // 0.15 mG per LSB
};
uint8_t Mscale = MFS_16BITS; // Choose either 14-bit or 16-bit
magnetometer resolution
uint8_t Mmode = 0x02;
const uint16_t i2c_timeoutB = 100;
/* USER CODE END PV */
/* Private function prototypes
-----------------------------------------------
*/ void SystemClock_Config(void); /* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code
---------------------------------------------------------
*/ /* USER CODE BEGIN 0 */
int _write(int file, char
*ptr, int len) { HAL_UART_Transmit(&hlpuart1, (uint8_t*)ptr, len,
HAL_MAX_DELAY);
return len;
}
float MagnetoX;
float MagnetoY;
float MagnetoZ;
/* USER CODE END 0 */
/**
- @brief <https://github.com/brief> The application entry point.
- @RetVal <https://github.com/RetVal> int
*/ int main(void) { /* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU
Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the
Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_LPUART1_UART_Init();
MX_I2C3_Init();
MX_I2C2_Init();
/* USER CODE BEGIN 2
*/ printf("**************************** \r\n");
printf("MPU9250 STM32 Implementation \r\n");
printf("**************************** \r\n");
//pre-def. vars
uint8_t readData;
uint8_t writeData;
// Check MPU and Mag---------------------------------------------------------------------------------------------------
//read MPU9255 WHOAMI
HAL_I2C_Mem_Read(&hi2c2, MPU9250_ADDRESS, WHO_AM_I_MPU9250, 1, &readData, 1, i2c_timeoutB);
printf("MPU WHO AM I is (Must return 113): %d\r\n", readData);
//enable Mag bypass
writeData = 0x22;
HAL_I2C_Mem_Write(&hi2c2, MPU9250_ADDRESS, INT_PIN_CFG, 1, &writeData, 1, i2c_timeoutB);
//read AK8963 WHOAMI
HAL_I2C_Mem_Read(&hi2c2, AK8963_ADDRESS, AK8963_WHO_AM_I, 1, &readData, 1, i2c_timeoutB);
printf("MAG WHO AM I is (Must return 72): %d\r\n", readData);
printf("------------------------------------------------\r\n");
//Init Mag-------------------------------------------------------------------------------------------------------------
//Power down magnetometer
writeData = 0x00;
HAL_I2C_Mem_Write(&hi2c2, AK8963_ADDRESS, AK8963_CNTL, 1, &writeData, 1, i2c_timeoutB);
HAL_Delay(100);
//Enter Fuse ROM access mode
writeData = 0x0F;
HAL_I2C_Mem_Write(&hi2c2, AK8963_ADDRESS, AK8963_CNTL, 1, &writeData, 1, i2c_timeoutB);
HAL_Delay(100);
//Read the x-, y-, and z-axis calibration values
uint8_t rawMagCalData[3];
HAL_I2C_Mem_Read(&hi2c2, AK8963_ADDRESS, AK8963_ASAX, 1, &rawMagCalData[0], 3, i2c_timeoutB);
float calMagX = (float)(rawMagCalData[0] - 128)/256. + 1.; // Return x-axis sensitivity adjustment values, etc.
float calMagY = (float)(rawMagCalData[1] - 128)/256. + 1.;
float calMagZ = (float)(rawMagCalData[2] - 128)/256. + 1.;
printf("Mag cal off X: %f\r\n", calMagX);
printf("Mag cal off Y: %f\r\n", calMagY);
printf("Mag cal off Z: %f\r\n", calMagZ);
HAL_Delay(100);
//Set magnetometer data resolution and sample ODR
writeData = Mscale << 4 | Mmode;
printf("writeData: %d\r\n", writeData);
HAL_I2C_Mem_Write(&hi2c2, AK8963_ADDRESS, AK8963_CNTL, 1, &writeData, 1, i2c_timeoutB);
HAL_Delay(100);
printf("------------------------------------------------\r\n");
//Read Mag-------------------------------------------------------------------------------------------------------------
//Read Mag data
uint8_t rawMagData[6];
HAL_I2C_Mem_Read(&hi2c2, AK8963_ADDRESS, AK8963_XOUT_L, 1, &rawMagData[0], 6, i2c_timeoutB);
float MagX = ((int16_t)rawMagData[1] << 8) | rawMagData[0];
float MagY = ((int16_t)rawMagData[3] << 8) | rawMagData[2];
float MagZ = ((int16_t)rawMagData[5] << 8) | rawMagData[4];
printf("Mag X: %f\r\n", MagX);
printf("Mag Y: %f\r\n", MagY);
printf("Mag Z: %f\r\n", MagZ);
HAL_Delay(100);
printf("------------------------------------------------\r\n");
/* USER CODE END 2 */
/* Infinite loop
*/ /* USER CODE BEGIN WHILE
*/ while (1) { /* USER CODE END WHILE */
//Read Mag data
uint8_t rawMagData[6];
HAL_I2C_Mem_Read(&hi2c2, AK8963_ADDRESS, AK8963_XOUT_L, 1, &rawMagData[0], 6, i2c_timeoutB);
MagX = ((int16_t)rawMagData[1] << 8) | rawMagData[0];
MagY = ((int16_t)rawMagData[3] << 8) | rawMagData[2];
MagZ = ((int16_t)rawMagData[5] << 8) | rawMagData[4];
//Print to Com port via STLINK
printf("Mag X: %f\r\n", MagX);
printf("Mag Y: %f\r\n", MagY);
printf("Mag Z: %f\r\n", MagZ);
printf("------------------------------------------------\r\n");
HAL_Delay(1000);
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
`
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Hi Kris, Actualy I solve the issue. It's all about wrong reading functions. I didn't read the status register, after the data registers, and didn't check AK8963_ST1 register either. I tweaked my code little and, now, It's works very well I gues. :) I'm using Nucle G431RB board, and here is the demo of it: https://www.youtube.com/watch?v=jB_gVwflhkY There is some jitter, besides the pitch - yaw - roll can become unstable. Would enabling low pass filter prevent this or needing to add any filter, like Kalman?
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Hi kriswiner,
I'm trying to implement the code you wrote for MPU9250BasicAHRS on my STM32 based Nucleo card. However, the magnetometer values are constantly being read.
I think that the magnetometer's power setting may have been stuck in read-once mode or off mode. I'm sharing my code, I would be very happy if you can help.
The text was updated successfully, but these errors were encountered: