RE: TWI slave

Kenneth — Mon, 28 Oct 2024 13:06:27 GMT

Hello,

Have you taken a look at the twi slave example?
https://docs.nordicsemi.com/bundle/sdk_nrf5_v17.1.0/page/twi_master_with_twis_slave_example.html

This example emulate an I2C eeprom, so I would think reading and writing is supported.

Kenneth

RE: TWI slave

Junichi — Fri, 25 Oct 2024 11:45:14 GMT

The TWI slave handler is created and executed as follows:

void twis_event_handler(nrf_drv_twis_evt_t const * p_event)
{
static bool address_received = false; // Track whether the register address was received

switch (p_event->type)
{
case NRFX_TWIS_EVT_READ_REQ:
// If there is a read request from the master
nrf_drv_twis_tx_prepare(&m_twis, &m_twi_register[m_register_address], TWI_BUFFER_SIZE - m_register_address);
NRF_LOG_INFO("Read request: register address = 0x%02X", m_register_address);
break;

case NRFX_TWIS_EVT_WRITE_REQ:
if (!address_received) {
// If the register address has not yet been received, prepare to receive the register address
NRF_LOG_INFO("Preparing to receive register address...");
nrf_drv_twis_rx_prepare(&m_twis, &m_register_address, 1);
} else {
// If register address received, prepare to write data
NRF_LOG_INFO("Register address received: 0x%02X", m_register_address);
if (m_register_address < TWI_BUFFER_SIZE) {
NRF_LOG_INFO("Preparing to write data to register 0x%02X", m_register_address);
nrf_drv_twis_rx_prepare(&m_twis, &m_twi_register[m_register_address], TWI_BUFFER_SIZE - m_register_address);
} else {
NRF_LOG_ERROR("Invalid register address: 0x%02X", m_register_address);
}
}
break;

case NRFX_TWIS_EVT_WRITE_DONE:
if (!address_received) {
// If register address was received
address_received = true; // Set flag
NRF_LOG_INFO("Register address 0x%02X received", m_register_address);
} else {
// If data was written
address_received = false; // Reset flag
NRF_LOG_INFO("Data written to register 0x%02X: 0x%02X", m_register_address, m_twi_register[m_register_address]);
}
break;

case NRFX_TWIS_EVT_READ_DONE:
NRF_LOG_INFO("Read completed");
break;

case NRFX_TWIS_EVT_READ_ERROR:
NRF_LOG_ERROR("TWIS EVT READ ERROR");
break;

case NRFX_TWIS_EVT_WRITE_ERROR:
NRF_LOG_ERROR("TWIS EVT WRITE ERROR");
break;

case NRFX_TWIS_EVT_GENERAL_ERROR:
NRF_LOG_ERROR("TWIS EVT GENERAL ERROR");
break;

default:
break;
}
}

Read works fine from the master side, but Write gives NRFX_TWIS_EVT_GENERAL_ERROR
and does not write to the register properly.
Please tell me the problem with the source.

RE: TWI slave

Turbo J — Tue, 15 Oct 2024 11:30:05 GMT

The code shown is incomplete, but I missed it when glancing over it.

The idea is to give the WRITE_REQ event a bigger buffer than one byte - and then to handle it in the "WRITE_DONE" event when there was >1 byte transmitted.

I recommend an oscilloscope / logic analyser. You should have seen the NACK in the write transaction on the bus since the buffer was too small.

RE: TWI slave

Junichi — Tue, 15 Oct 2024 10:45:37 GMT

Thank you for your answer.

Please give me a bit more detail.

RE: TWI slave

Turbo J — Tue, 15 Oct 2024 08:27:09 GMT

Error is in code not shown.