Multiple PICs on usart network

[ardhuru]

Thanks, Andy.

Actually, there's nothing to it, really.

Just set up the Rx and Tx routines as shown in the graphic (substitute the pin you're actually using in place of the C.6 I've shown) and call Tx before each transmission, and Rx before receiving (or more accurately, after each transmission).

So, at any time, only one guy is transmitting.

And, make sure the pin you're using is set for digital I/O, of course.

Anand

[andymuller]

Thanks, Andy.

Actually, there's nothing to it, really.

Hello Anand,

Thank you very much buddy in advance for your replying me.

In brief, I am beginner at PIC world, and absolutely not expert such as you bro.

Would you mind if you share an applicable sample here (for Master and slaves), please?

I would deeply appreciate for your understanding and most valuable support.

Regards,

Andy

[Demon]

test post to open a closed thread (I have a pending post)

can be deleted once another post is added (thread auto-closes if I remove this one)

[Ioannis]

I can post here just fine. I see it opened.

Ioannis

[DaveP]

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

[Demon]

I can post here just fine. I see it opened.

Ioannis

Me too. But if I removed my post, the thread closed again.

[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.