I take the TWI master example of nordic, and try to build I2C read API that can be use from otherr places.
The function look like this
uint32_t Serial_read_2BytesReg(uint8_t instance,uint8_t dev_add, uint16_t reg_add,void const * p_buffer,size_t size, nrf_twi_mngr_callback_t callback_fn )
{
uint32_t error;
nrf_twi_mngr_t * p_nrf_twi_mngr_instance;
uint8_t reg_addr_uint8[]= { ((uint8_t)(reg_add>>8)),((uint8_t)(reg_add))};
nrf_twi_mngr_transfer_t transfers[] ={
{ /* write sequence */
.p_data = reg_addr_uint8, // the reg address should be read from
.length = 2, // size of reg address in uint8_t units
.operation = (((dev_add) << 1) | 0), // address of the device include the write command
.flags = NRF_TWI_MNGR_NO_STOP // no stop continue to the read
},
{ /* read sequence */
.p_data = (uint8_t*)p_buffer, // buffer to place the receive data read
.length = size, // size of data to read in uint8 units
.operation = (((dev_add) << 1) | 1), // address of the device include the read command
.flags = 0 // stop communication
}};
nrf_twi_mngr_transaction_t NRF_TWI_MNGR_BUFFER_LOC_IND transaction =
{
.callback = callback_fn,
.p_user_data = NULL,
.p_transfers = transfers,
.number_of_transfers = sizeof(transfers) / sizeof(transfers[0])
};
switch(instance)
{
#if TWI0_ENABLED
case 0:
p_nrf_twi_mngr_instance = &m_nrf_twi_mngr_sec;
break;
#endif // TWI0_ENABLE
#if TWI1_ENABLED
case 1:
p_nrf_twi_mngr_instance = &m_nrf_twi_mngr;
break;
#endif
default:
p_nrf_twi_mngr_instance = NULL;
break;
}
if ( p_nrf_twi_mngr_instance == NULL)
{
return !NRF_SUCCESS;
}
error = nrf_twi_mngr_schedule(p_nrf_twi_mngr_instance, &transaction);
return error; // NRF_SUCCESS =0 all other error
}
When I stop before the nrf_twi_mngr_schedule I check the contain of the register especially the transfer and transaction and this is what they have in:
I have problem with the first write build.
It build the device address with write (0x74) and then the reg add is 0x240b. I get the 0x24 but then 0x70 . It continue with the device address read (0x75) and then send 2 byes clk. I see it return 0x00 and the NACK but on my SWI don't get to the callback and I jump into error on HardFault_Handler.
Is there any clue what I did wrong in the function?
Bar.
