RE: I2C TWI

Abrar — Fri, 07 Jan 2022 06:07:05 GMT

#define TWI_INSTANCE_ID 0 // create a ID constant

static volatile bool m_xfer_done = false;

static const nrf_drv_twi_t m_twi = NRF_DRV_TWI_INSTANCE(TWI_INSTANCE_ID);

void twi_handler(nrf_drv_twi_evt_t const* p_event, void * p_context)
{
switch (p_event-> type)
{
case NRF_DRV_TWI_EVT_DONE:
break;

m_xfer_done = true;
break;

default:
break;
}
}

// a function to initialize the twi(i2c)
void twi_master_init(void)
{
ret_code_t err_code;

const nrf_drv_twi_config_t twi_config = {
.scl = 27,
.sda = 26 ,
.frequency = NRF_DRV_TWI_FREQ_100K,
.interrupt_priority = APP_IRQ_PRIORITY_HIGH,
.clear_bus_init = false

err_code = nrf_drv_twi_init(&m_twi, &twi_config, NULL, NULL);

APP_ERROR_CHECK(err_code);
nrf_drv_twi_enable(&m_twi);
}

s8 BNO055_I2C_bus_write(u8 dev_addr, u8 reg_addr, u8 *reg_data, u8 cnt)
{

ret_code_t err_code;
s32 BNO055_iERROR = BNO055_ZERO_U8X;
u8 array[I2C_BUFFER_LEN];
u8 stringpos = BNO055_ZERO_U8X;
m_xfer_done = false;
array[BNO055_ZERO_U8X] = reg_addr;

err_code =nrf_drv_twi_tx(&m_twi, BNO055_I2C_ADDR1,array,I2C_BUFFER_LEN,false );

while (m_xfer_done == false)
{
}

if (NRF_SUCCESS != err_code)
{
return false;
}

for (stringpos = BNO055_ZERO_U8X; stringpos < cnt; stringpos++)
{
array[stringpos + BNO055_I2C_BUS_WRITE_ARRAY_INDEX] = *(reg_data + stringpos);
}
}

s8 BNO055_I2C_bus_read(u8 dev_addr, u8 reg_addr, u8 *reg_data, u8 cnt)
{
ret_code_t err_code;

m_xfer_done = false;
s32 BNO055_iERROR = BNO055_ZERO_U8X;
u8 array[I2C_BUFFER_LEN] = { BNO055_ZERO_U8X };
u8 stringpos = BNO055_ZERO_U8X;

array[BNO055_ZERO_U8X] = reg_addr;

err_code= nrf_drv_twi_tx(&m_twi, BNO055_I2C_ADDR1, array, 1, true );

while (m_xfer_done == false)
{}
if (NRF_SUCCESS != err_code)
{
return false;
}
m_xfer_done=false;

err_code=nrf_drv_twi_rx (&m_twi,BNO055_I2C_ADDR1,reg_data, cnt);
while (m_xfer_done == false)
{}
if (NRF_SUCCESS != err_code)
{
return false;
}
for (stringpos = BNO055_ZERO_U8X; stringpos < cnt; stringpos++)
{
*(reg_data + stringpos) = array[stringpos];
}

return (s8)BNO055_iERROR;
}

Is this one correct?

RE: I2C TWI

Stian Røed Hafskjold — Thu, 06 Jan 2022 14:53:12 GMT

Hi, you should start out with an I2C sample from the SDK, to see how it works, and then do the necessary modifications.

If you are using the nRF5 SDK, you can start with this sample: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/twi_sensor_example.html?cp=8_1_4_6_43

For Zephyr, you can probably start with one of the sensor applications that uses I2C: http://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/samples/sensor/sensor.html