MDot as SPI master and introducing delays between writes.

[Ajay K]

I have two development kits based on arm processors which are mbed enabled. One of the kits is the Multitech’s mdot UDK kit and the other is the Nordics nrf52_dk.

The mdot behaves as the SPI master and the nrf52 the SPI slave. I am using the out of box MBED SPI and SPI slave API’s to communicate between the two devices. I have managed to get the applications on both the devices to communicate over SPI.

The Master and SPI slave, have been configured for 8 bit data, in Mode 0 with a 1MHz clock rate.

With the MBED SPI API, in order to read a byte from slave, I need to write a byte..

However in the SPI master (i.e. in the mdot) I have to introduce a delay as much as half a second/to almost second between each of my writes to successfully read anything from the NRF52, otherwise either I lose data that is sent from the NRF52 or it seems like NRF52 doesn’t respond to master writes.

Is there anything I need to configure in mdot to ensure the data is transmitted without introducing delays between transmissions to receive data from nrf52 without any issues.

Thanks,
Ajay

[Leon Lindenfelser]

Hi Ajay,

Have you put a scope on the SPI lines to see what is happening? Does the master drive the MOSI line as expected? Does the slave drive the MISO line as expected?

Kind regards,
Leon

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