When calling nrf_drv_twi_tx() once like in the snippet below it works, but when the function is called two or more times sequentially, it fails. However running a nrf_delay_ms() delay between the calls makes it work again.
Works
nrf_drv_twi_init(&twi, NULL, NULL);
nrf_drv_twi_enable(&twi);
nrf_drv_twi_tx(&twi, addr, &(buf[0]), buf_size, false);
Fails
nrf_drv_twi_init(&twi, NULL, NULL);
nrf_drv_twi_enable(&twi);
nrf_drv_twi_tx(&twi, addr, &(buf[0]), buf_size, false);
nrf_drv_twi_tx(&twi, addt, &(buf[0]), buf_size, false);
Works again
nrf_drv_twi_init(&twi, NULL, NULL);
nrf_drv_twi_enable(&twi);
nrf_drv_twi_tx(&twi, addr, &(buf[0]), buf_size, false);
nrf_delay_ms(10);
nrf_drv_twi_tx(&twi, addt, &(buf[0]), buf_size, false);
It fails simply by running the app_error_handler. Which spits out some corrupted data over the serial interface.
Solved
The flash IC I'm using requires a 10ms wait between each write. Therefore the IC would NACK the second write if it hasn't been 10ms since the last write.
