RE: Delay time bewteen two transfer

Jørn — Mon, 29 May 2017 14:40:45 GMT

Hello pikachu

The time it takes for a transfer depends on your transfer rate, in your case 125kb/s, and the amount of data you are transmitting. In the example it transmits the text "Nordic", where each letter is represented with 8 bits. This should give a minimum transfer time of approximately 6*8/125000=384us.

In the spi example you refer to you have the

    while (!spi_xfer_done)
    {
        __WFE();
    }

In the main loop. This flag is set in the spi_event_handler which is called upon an spi event, such as transfer complete. This way it waits until the previous transfer is complete before attempting a new one. I recommend reading the SPI section of the nRF51 reference manual, for specifics on timing you can see the electrical specifications of the nRF51xxx product specification (the development kit uses nRF514222.

Best regards

Jørn Frøysa