hardware UART inversion success

[mskala]

Not a problem, a success

In all the previous threads, it has been pointed out that CCS uses INVERT only with software uarts on the various PICs. As far as I know the CCS command is still true, but:

In the PIC184550, rev B4 and later, check out bits RXDTP and TXCKP. They do inversion on the hardware uart. I tested RXDTP only, and it works. Just set the RXDTP bit in your code after #use_rs232.

Why is this important? In my case, I want to be able to input RS232 data from modules that may or may not contain a MAX232 chip, some just send TTL level data. (See many GPS devices.) For RX only, I have the 'hack' transistor inverting receiver circuit. If RXDTP is set properly I can receive either type of data fine. (Probably could have software figure it out on the fly but not necessary for me).

I believe several of the PIC18's have this feature now.

Just for your info,
Mark S.

[treitmey]

This is also good for me. I print debug to the inverted uart.
Before that would halt all processing.

Now I can put the message in a buffer and let the interrupt
trickle the data out at its own pace.

Great!

[PCM programmer]

I didn't know about this. Thanks. If you Google for this, you'll find
more 18F chips with the new feature:

[mskala]

This may have been out for a while. Digikey sold me B6 several months ago.

Errata for it seems to have a date of 7/2007.