How to prevent STOP bit after a TWI rx command?

RE: How to prevent STOP bit after a TWI rx command?

bearsh — Tue, 18 Jun 2024 15:22:49 GMT

a little bit late to the party

cor10 did the suggestion of Kenneth work for you? I have a similar problem to solve...

RE: How to prevent STOP bit after a TWI rx command?

cor10 — Wed, 17 Nov 2021 00:18:09 GMT

Hi Kenneth,

Thank you for your response! I will look into setting this up, much appreciated.

I have one last question to address for this project I am starting on, and although it is still related to I2C/TWI, it is a different topic, so I created a new ticket: https://devzone.nordicsemi.com/f/nordic-q-a/81811/i2c-reads-writes-how-to-communicate-with-a-7bit-i2c-slave-that-has-a-16bit-memory-map

Any feedback on this new ticket would be super appreciated. Thanks again

RE: How to prevent STOP bit after a TWI rx command?

Kenneth — Mon, 15 Nov 2021 13:30:36 GMT

Hi,

I have tried to look at the driver, but I can't find that your use case is supported. It looks like all defined macros that show usage of twi transfer all ends with a stop condition and a stop interrrupt.

My suggestion would be to create a new macro, for instance based on the implementation of NRFX_TWIM_XFER_RX:

    case NRFX_TWIM_XFER_RX:
        nrf_twim_rx_buffer_set(p_twim, p_xfer_desc->p_primary_buf, p_xfer_desc->primary_length);
        nrf_twim_shorts_set(p_twim, NRF_TWIM_SHORT_LASTRX_STOP_MASK);
        p_cb->int_mask = NRF_TWIM_INT_STOPPED_MASK;
        start_task = NRF_TWIM_TASK_STARTRX;
        nrf_twim_task_trigger(p_twim, NRF_TWIM_TASK_RESUME);
        break;

But instead you should not enable the STOPPED interrupt mask and not enable the lastrx to stop shortcut. Likely you should instead enable the LASTRX interrupt mask, and not have any shortcuts enabled. Then in the twim_irq_handler() you would want to add handling of the LASTRX interrupt, this should be similiar to handling the STOPPED interrupt (;check and clear event, disable interrupt, and possible call the callback handler).

Best regards,
Kenneth