Radio TX truncation

RE: Radio TX truncation

bbrittain — Wed, 20 Jul 2022 17:06:42 GMT

While figuring out exactly how many bytes were exactly transmitted I realized my other radio was actually picking up the whole transmission sequence!

The issue here is, surprisingly, not my code but the 802.15.4 chip on my linux box! I have no idea what I'm gonna do about that but I've confirmed now that this is working as intended. Thanks so much for trying to help

RE: Radio TX truncation

Kenneth — Wed, 20 Jul 2022 13:16:34 GMT

And the transmit/receive buffers are a static volatile array that is not somehow reused by the compiler? How many bytes can you succesfully transmit before it start to truncute the data?

Kenneth

RE: Radio TX truncation

bbrittain — Wed, 20 Jul 2022 13:13:53 GMT

Unfortunately not. It's 7 bytes zeroed at the end, not two. Additionally, even though the radio peripheral sets the CRC I've been including it as part of the PHR field length since the spec specifies "the PHY data will be a MAC frame of N-2 octets since two octets will occupy a CRC field. "

RE: Radio TX truncation

Kenneth — Wed, 20 Jul 2022 11:49:16 GMT

I can find from the datasheet: "The total usable payload (PSDU) is 127 octets, but when CRC is being used, this is reduced to 125 octets of usable payload."

Can that explain what you see?

Kenneth

RE: Radio TX truncation

bbrittain — Tue, 19 Jul 2022 16:40:25 GMT

The PHR length field in the PPDU is set the same way it is for the smaller packets and never exceeds 127. The buffer pointed at by the packetptr contains the expected bits. The CRC is calculated correctly by the hardware (as verified by being received on the other side!)