Multiple PICs on usart network

[DaveP]

This comm scheme sounds like ISO-9141. Been around for years.

[Demon]

This comm scheme sounds like ISO-9141. Been around for years.

I saw a mention further up the thread about 1-wire comm.

OBD-II signal protocols. ISO 9141-2. This protocol has an asynchronous serial data rate of 10.4 kbit/s. It is somewhat similar to RS-232; however, the signal levels are different, and communications happen on a single, bidirectional line without additional handshake signals.

https://en.wikipedia.org/wiki/On-boa...hake%20signals.


I'm planning on using standard 2-wire hardware USART.

[Ioannis]

OBD-II signal protocols. ISO 9141-2. This protocol has an asynchronous serial data rate of 10.4 kbit/s. It is somewhat similar to RS-232; however, the signal levels are different, and communications happen on a single, bidirectional line without additional handshake signals.

https://en.wikipedia.org/wiki/On-boa...hake%20signals.


I'm planning on using standard 2-wire hardware USART.

Car automakers had to do it with better electrical characteristics I guess.

I'd also choose 2 wires USART classic setup. Tested and guarrateed to work just fine.

Ioannis

[Demon]

...The last byte (13) will not go thru properly because the tranceiver chip is switched from Tx to Rx mode in the middle of it....

/Henrik.

The original project was just a personal home alarm system.

But now I'm designing a controller for flight sim that I plan on marketing. I'm considering using a combination of everything said in this thread, including your comment.

- separate TX and RX lines.
- tri-state busy line for slaves.
- tri-state busy line for master (for future expansion).
- enable/disable TX in slaves.
- add an extra byte in transmission so no data is lost during transition between enable/disable (if I can't identify exactly how to avoid dropping that byte).
- slaves only talk when spoken to by master.
- prefix in communication identifies which slave is targeted.
- slaves can "raise their hand" to speak using slave busy line.
- basic checksum.
- highest speed supported by 16F1455, 16F1937, 16F18855 and 16F18877.
- two 4K7 pull-up resistors on master (or maybe 10K, remains to be determined).

That's pretty much what I have identified to start.

[Demon]

For those that are curious about 1-wire communication, check out Dallas 1-wire:

https://ww1.microchip.com/downloads/...S00002658B.pdf

[Ioannis]

Interesting article.

Thanks for sharing.

Ioannis

[andymuller]

For those that are curious about 1-wire communication, check out Dallas 1-wire:

https://ww1.microchip.com/downloads/...S00002658B.pdf

Thank you Demon
Valuable data
Appreciate.