Unable to read acceleration of BMA456

[sat3_3]

Hi,

I want to read only the raw sensor values, but it doesn't work. I'm using an 8-bit MCU, so I'd like to read data with the minimum configuration. It seems possible according to the topics below, but could you please tell me what I am missing?

https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BMA456-without-configuration-file/td-p/5...

chip_ID is being read correctly.

#define BMA4_ACC_X_LOW                            UINT8_C(0x12)
#define BMA4_ACC_X_HIGH                           UINT8_C(0x13)

uint8_t data, status = 0;

i2c_single_byte_write(BMA4_I2C_ADDR_PRIMARY, BMA4_POWER_CONF_ADDR, 0x00);
delay_ms(1);

i2c_single_byte_write(BMA4_I2C_ADDR_PRIMARY, BMA4_POWER_CTRL_ADDR, 0x04);
delay_ms(500);

status = i2c_single_byte_read(BMA4_I2C_ADDR_PRIMARY, BMA4_STATUS_ADDR); // read status = 0x90
data = i2c_single_byte_read(BMA4_I2C_ADDR_PRIMARY, BMA4_ACC_X_LOW); // read data = 0x00

[BSTRobin]

Hi sat3_3,

Thanks for your inquiry.
We conducted tests, BMA456 can read data from registers without loading configuration file.
I have attached an example on STM32 32-bit MCU for your reference.

void run_without_config_file(void)
{
int8_t rslt;
uint8_t reg_data, command_reg, status;
uint8_t data[BMA4_ACCEL_DATA_LENGTH] = { 0 };
uint16_t lsb = 0, msb = 0;
int16_t x, y, z;
uint8_t bma456_i2c_addr;

bma456_i2c_addr = BMA4_I2C_ADDR_SECONDARY;
SensorAPI_I2Cx_Read(BMA4_CHIP_ID_ADDR, &reg_data, 1, &bma456_i2c_addr);
PDEBUG("Chip ID:0x%02x\r\n", reg_data);

command_reg = 0xB6;
SensorAPI_I2Cx_Write(BMA4_CMD_ADDR, &command_reg, 1, &bma456_i2c_addr);
HAL_Delay(100);

bma456_i2c_addr = BMA4_I2C_ADDR_SECONDARY;
SensorAPI_I2Cx_Read(BMA4_CHIP_ID_ADDR, &reg_data, 1, &bma456_i2c_addr);
PDEBUG("Chip ID:0x%02x\r\n", reg_data);

reg_data = 0;
SensorAPI_I2Cx_Write(BMA4_POWER_CONF_ADDR, &reg_data, 1, &bma456_i2c_addr);
bst_delay_us(450,NULL);

reg_data = 0x04;
SensorAPI_I2Cx_Write(BMA4_POWER_CTRL_ADDR, &reg_data, 1, &bma456_i2c_addr);
bst_delay_us(2,NULL);

SensorAPI_I2Cx_Read(BMA4_STATUS_ADDR, &reg_data, 1, &bma456_i2c_addr);
PDEBUG("Status:0x%02x\r\n", reg_data);

for(int i=0;i<100;i++)
{
SensorAPI_I2Cx_Read(BMA4_DATA_8_ADDR, data, BMA4_ACCEL_DATA_LENGTH, &bma456_i2c_addr);
msb = data[1];
lsb = data[0];

/* Accel data x axis */
x = (int16_t)((msb << 😎 | lsb);
msb = data[3];
lsb = data[2];

/* Accel data y axis */
y = (int16_t)((msb << 😎 | lsb);
msb = data[5];
lsb = data[4];

/* Accel data z axis */
z = (int16_t)((msb << 😎 | lsb);

PDEBUG("data X: %d, Y: %d, Z: %d\r\n", x, y, z);
HAL_Delay(500);
}
}

[sat3_3 · Accepted solution]

Hi BSTRobin,

Thank you for your support.

I tried implementing it based on the sample code you provided, but it didn't work. The sample code uses BMA4_I2C_ADDR_SECONDARY, but will it work with PRIMARY as well? I would like to receive any other advice.

I suspected a malfunction and tried other chips, but the result was the same. I have attached the circuit diagram. Could you also check the problem with the circuit?

    uint8_t reg_data, command_reg, status;
    uint8_t data[BMA4_ACCEL_DATA_LENGTH] = { 0 };
    uint16_t lsb = 0, msb = 0;
    int16_t x, y, z;
    int8_t addr = BMA4_I2C_ADDR_PRIMARY;

    reg_data = i2c_single_byte_read(addr, BMA4_CHIP_ID_ADDR);
    DebugPrint("CHIP ID: %x\r\n", reg_data);

    i2c_single_byte_write(addr , BMA4_CMD_ADDR, 0xB6);
    delay_ms(100);

    reg_data = i2c_single_byte_read(addr, BMA4_CHIP_ID_ADDR);
    DebugPrint("CHIP ID: %x\r\n", reg_data);

    i2c_single_byte_write(addr , BMA4_POWER_CONF_ADDR, 0x00);
    delay_us(450);
    i2c_single_byte_write(addr , BMA4_POWER_CTRL_ADDR, 0x04);
    delay_us(2);

    reg_data = i2c_single_byte_read(addr, BMA4_STATUS_ADDR);
    DebugPrint("STATUS: %x\r\n", reg_data);
    delay_ms(500);

    while(1){
        data[0] = i2c_single_byte_read(addr, BMA4_ACC_X_LOW);
        data[1] = i2c_single_byte_read(addr, BMA4_ACC_X_HIGH);
        data[2] = i2c_single_byte_read(addr, BMA4_ACC_Y_LOW);
        data[3] = i2c_single_byte_read(addr, BMA4_ACC_Y_HIGH);
        data[4] = i2c_single_byte_read(addr, BMA4_ACC_Z_LOW);
        data[5] = i2c_single_byte_read(addr, BMA4_ACC_Z_HIGH);

        msb = data[1];
	lsb = data[0];

	/* Accel data x axis */
	x = (int16_t)((msb <<  | lsb);
	msb = data[3];
	lsb = data[2];
     
        /* Accel data y axis */
	y = (int16_t)((msb <<  | lsb);
	msb = data[5];
	lsb = data[4];

	/* Accel data z axis */
	z = (int16_t)((msb <<  | lsb);

	DebugPrint("data X: %d, Y: %d, Z: %d\r\n", x, y, z);
	delay_ms(500);
    }

schematic

[sat3_3]

There was a problem with the I2C library we were using. We fixed it and confirmed that BMA456 works properly.