crc blocking

[Elektrika]

Greetings from a Nordic newbie!

I am currently merging an existing AD 433MHz transceiver with a nRF51422 so that I can read an ANT+ heartrate monitor to our existing functionality.

My big question is, can I loose my existing processor.

Right now, I need to process incoming data 1 bit a time from a AD 433MHz radio, at a rate of 1200 baud. So on every cycle from the existing radio I do a CRC comparison of my incoming data (which I need to que) with my CRC block.

This poses two problems:

1. Can I deterministically respond to the external radios 1200Hz interrupt while the S110 firmware is running? This seems to be in the order of 400uS so it seems I am ok.

and

2. How long will the nRF51422 block my access to the CRC module? I assume the firmware will lock me out and vice versa so that we do not stand on each others data (is it that easy?).

Thanks in advance Steve

[Anders Strand]

Hello.

You cannot use the crc block of the nRF51 radio to generate crc's for you. It will generate crc's for radio packets going out, and radio packets coming in. The latter ones you can extract, but i dont think this will be of use to you.

You can compute crc's in software, it should not demand much computing.

Since you will get radio interrupts from the 433 MHz at 1200 baud, this will be an interrupt roughly every 800 us (if i understood you correctly). If you take a look at chapter 11.2 of the softdevice s210 specification you will see that the softdevice will occupy the cpu from time to time. These tasks can take about 400 us.

I think you should be able to sucessfully detect all 433 MHz interrupts, but this should be tested.

-Anders