[SPIM+TIMER+PPI] Issue regarding the handlers for SPIM and TIMER.

Question

Hello,

I am programming BLE with the nRF52840-DK. [Toolchain Manager: v1.3.0, IDE: Visual Studio Code (VSCode), SDK: ncs v2.6.0, window11 pro]

< Simple Code Explanation >

1. The ADC (SLAVE) and nRF52840 DK (MASTER) communicate via SPIM.

2. A command is sent to the ADC at regular intervals defined by 'TIME_TO_WAIT_US'.

The TIMER is used to measure the intervals and PPI is used to start SPIM.
The command buffer includes tx_buf_array and tx_buf_array_2. (nRF52840 DK -> ADC)
tx_buf_array is a command for ADC initialization.
tx_buf_array_2 is a command to retrieve ADC data and is intended to be sent repeatedly.
The SPIM handler exists to modify Tx_PTR and to signal the end of SPIM.
The TIMER handler exists to signal the end of the TIMER.

< my issue>

If TIME_TO_WAIT_US is less than 10, SPIM communication does not work properly. (ADC spec: Maximum SCLK frequency is 25 MHz)

I think a lot of time is being consumed in the handler. I'm not sure exactly what the problem is.

I want SPIM to work properly when 'TIME_TO_WAIT_US' is 5~6.

Could you give me some advice?

- Below is my code for the handler part:

void spim1_handler(nrfx_spim_evt_t const * p_event, void * p_context) {   
	//LOG_INF("spim1_handler[%d] - TXD.PTR: 0x%08X", spi_counter, spim1_inst.p_reg->TXD.PTR);
	if(spim1_inst.p_reg->TXD.PTR == (uint32_t)&tx_buf_array_2[17] + 2) {
        spim1_inst.p_reg->TXD.PTR = (uint32_t)tx_buf_array_2[0];
    } else if(spim1_inst.p_reg->TXD.PTR == (uint32_t)&tx_buf_array[30] ) {
        spim1_inst.p_reg->TXD.PTR = (uint32_t)tx_buf_array_2[0];
    }
	if(spi_counter == MAX_SPI_COUNT){
		spi_disable(spim1_inst.p_reg);
        k_sem_give(&sem_condition1);
    }
    spi_counter++;
}

void timer0_handler(nrf_timer_event_t event_type, void * p_context){   
	if(spi_counter == MAX_SPI_COUNT){
		timer_disable(&timer0_inst);
        k_sem_give(&sem_condition2); 
    }
}

- Below is my code for the ppi part:

    /*   PPI  Setting  */
    uint32_t gpiote_task_addr = nrfx_gpiote_out_task_address_get(&gpiote_inst ,SS_PIN_MASTER);    
    uint32_t timer_start_compare_event_addr = nrfx_timer_compare_event_address_get(&timer0_inst, NRF_TIMER_CC_CHANNEL0);
    uint32_t spi_start_task_addr   = nrfx_spim_start_task_address_get(&spim1_inst);
    uint32_t spi_end_evt_addr = nrfx_spim_end_event_address_get(&spim1_inst);

    // Timer reaches the desired tick -> GPIOTE toggle(off), SPI start
    error = nrfx_gppi_channel_alloc(&ppi_channel_spi_start);
    nrfx_gppi_channel_endpoints_setup(ppi_channel_spi_start, timer_start_compare_event_addr, gpiote_task_addr);
    nrfx_gppi_fork_endpoint_setup(ppi_channel_spi_start, spi_start_task_addr);

    // SPI tx-rx transmission ends -> GPIOTE toggle(on)
    error = nrfx_gppi_channel_alloc(&ppi_channel_spi_end);
    nrfx_gppi_channel_endpoints_setup(ppi_channel_spi_end, spi_end_evt_addr, gpiote_task_addr);

[SPIM+TIMER+PPI] Issue regarding the handlers for SPIM and TIMER.

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