I am new to FreeRTOS and Thread/Bluetooth. We have an NXP FRDM KW41Z demo module running the thread wireless protocol and bluetooth stacks based on FreeRTOS. We have a requrement where we need to add an SPI interface to communicate with an external device based on the existing application under FreeRTOS . I was wondering if anyone knows of any application notes/turorial/tips/advice to the get SPI communication running. I would be most grateful for any input please. Thanks a lot.
Is this a general SPI question (in which case I would recommend starting
with Wikipedia), a question specific to the SPI on the NXP chip (in
which case I would recommend the datasheet for the part, or any
application notes from NXP), or a question on using a NXP (or other) SPI
driver with FreeRTOS?
Thank you so much for getting back to me.
Although I am familiar with general SPI operation, we have an NXP FRDM KW41Z SDK as mentioned above and there are references to SPI in the code provided that came with the SDK…I guess my question is, do I need to create my own tasks from scratch to handle SPI communication via FreeRTOS?..e.g. set up a tasks to transmit and receive SPI data? … or are FreeRTOS libraries normally provided to handle serial communications?..if so how do “inform” or “initialise” FreeRTOs to include handling serial communication tasks etc…for example I couldn’t find an interface that allows me to specify SPI protocol parameters (eg number of data bits for example)
Thanks a lot
I would not normally create a task specifically to handle serial
communication, but call the serial input an output functions (normally
provided by the MCU vendor) inline from whichever task needed to perform
the IO. I’m sure NXP will have examples of this in their libraries.
In an ideal case there would be DMA like facilities on the serial
peripheral to handle the transactions for you and just provide you will
a buffer of received data. More usually you can handle serial IO
transactions in interrupts, so you start the transaction with a function
call, then use interrupts generated by the transaction to keep the
input/output bytes inputting/outputting until the end of the message,
then use an interrupt safe FreeRTOS function to unblock a task that was
waiting for the transaction to complete.
You can see the examples on the following pages for some ideas:
Hi Richard,
OK, I will go through the links provided and also have a look at what functions NXP have already implemented.
Thanks a lot for your help.
Para