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A comment on PJON 12.0 – Networking freedom for hackers, makers and experimenters. Parent comment

Re:PJON 12.0 – Networking freedom for hackers, makers and ex... by Animats on Saturday November 02, 2019 @05:50PM (#21430346)
There's an optional 8-bit CRC and sequence number, with a single bit ACK.[1] This is even weaker than ARCnet, circa 1977, one of the earliest protocols for talking to low-end devices.

This is for talking to things like lightbulbs with some US$0.50 CPU inside. It's for really low end devices. It's best for idempotent operations that can be requested repeatedly without harm and are timeout-tolerant.

[1] https://github.com/gioblu/PJON/blob/master/specification/PJO...

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Re:PJON 12.0 – Networking freedom for hackers, makers and ex... by filar on Saturday November 02, 2019 @06:09PM (#21430455)
Small correction: Using CRC is not optional. Setting the crc flag makes it use CRC32 even for very small packets. The default is to use CRC8 for packets of a few bytes and then upgrade to CRC32 over a small size threshold. This is to minimize the size of otherwise tiny packets.

Also, the ACK implementation depends on the strategy (physical media type), and it is not a single bit but a single byte, and it seems to me to be robust. I am sure the creator, gioblu, has some more comments about this.

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