TWI doesn't work when a handler is set

RE: TWI doesn't work when a handler is set

Jørgen Holmefjord — Wed, 31 Jan 2018 09:35:33 GMT

What is not called? The interrupt handler? I recommend that you post a new thread where you described your code and the issue in more details. This will make it easier to help you get your issue sorted out.

RE: TWI doesn't work when a handler is set

Steph van Schalkwyk — Tue, 30 Jan 2018 19:54:41 GMT

I'm getting the same problem. I've removed all NRF_LOG_* from the interrupt handler, but it still isn't called.

const nrf_drv_twi_config_t twi_SI7021_config = {
       .scl                = ARDUINO_SCL_PIN,
       .sda                = ARDUINO_SDA_PIN,
       .frequency          = NRF_TWI_FREQ_100K,
       .interrupt_priority = APP_IRQ_PRIORITY_LOW, // I've tried HIGH
       .clear_bus_init     = false
    };

err_code = nrf_drv_twi_init(&m_twi, &twi_SI7021_config, twi_handler, NULL);

RE: TWI doesn't work when a handler is set

MartinBL — Thu, 11 Jan 2018 10:21:37 GMT

A little late to the party, but for future readers I just answered a similar question here:

NRF_LOG_FLUSH() is a blocking function and if you are using UART as backend this is using interrupts while printing messages. Hence, you are triggering interrupts from within an interrupt context and this might cause priority issues. If you are using RTT as backend it will not use interrupts the same way, but since NRF_LOG_FLUSH() is blocking and since it takes a significant amount of time to format a string you should never flush in an interrupt context. NRF_LOG_FLUSH() is intended to be used only in main context.

RE: TWI doesn't work when a handler is set

zolotiyeruki — Tue, 25 Jul 2017 19:04:08 GMT

It appears that having NRF_LOG_FLUSH() in the event handler is what causes the problem. I don't know the precise root cause, but I suspect that it has something to do with calling it from within what is effectively an ISR. Removing that statement allowed the code to run as expected.

RE: TWI doesn't work when a handler is set

zolotiyeruki — Tue, 25 Jul 2017 19:03:40 GMT

RE: TWI doesn't work when a handler is set

zolotiyeruki — Tue, 25 Jul 2017 16:00:58 GMT

Here's the nrf_drv_twi_config_t:

    const nrf_drv_twi_config_t twi_lm75b_config = {
   .scl                = ARDUINO_SCL_PIN,
   .sda                = ARDUINO_SDA_PIN,
   .frequency          = NRF_TWI_FREQ_100K,
   .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
   .clear_bus_init     = false
};

I actually used the twi_scanner code as the basis for my main.c, although there's little resemblance left after all my edits :) I'll try modifying the twi_sensor example and see if I have any more luck.

RE: TWI doesn't work when a handler is set

Knut Auvor Grythe — Tue, 25 Jul 2017 06:52:48 GMT

I don't see anything particularly wrong with the way you're initializing twi, although you're not sharing the contents of your nrf_drv_twi_config_t. Your main() doesn't have logic for waiting for the interrupt, but I assume you know that. Have you considered starting with the examples/peripheral/twi_sensor example in the SDK? It's a relatively simple interrupt-based TWI example.