RS232 Bitwise

Shoebie · Joined: 07 Nov 2007 Posts: 5

I am using a PIC16F876, not by choice, I would have preferred the 877. However, here is my problem. I am already using the built in uart, however, I need a second RS232 output. I have done this in assembly, but would like to accomplish this in C. Here is my simple code, which generates the wrong duration pulses when looked at with a scope.

jecottrell · Joined: 16 Jan 2005 Posts: 559 Location: Tucson, AZ

Instead of trying to code your own software UART, wouldn't you rather use the CCS feature to handle it? I'm assuming you don't know that you can do that?

Guest · Posted: Wed Nov 07, 2007 10:10 pm

I use the PIC uart for another task. I need to send out another rs232 string for a differnt task and have to use another port besides RC6 and 7. The port I can use is RC2.

Thanks for the reply. I use the internal uart when I can. Just this time, I need 2, and the 876 doesn't have 2.

Ttelmah · Guest

You are missing the point.
The CCS code, supports use of both the hardware UART, and generation of 'software' UARTs. If you use the two hadware pins in the #use RS232 statement, it generates short code to use the hardware UART. However if you use exactly the same line, but on pins that do not have the hardware UART, it _automatically_ generates software serial code. Hence you can use (for example):

Shoebie · Joined: 07 Nov 2007 Posts: 5

I'll give that a try. I didn't realize you could set up 2 uart software modules.

Thanks!

rnielsen · Joined: 23 Sep 2003 Posts: 852 Location: Utah

You can have, pretty much, as many software TX pins as you want. RX pins are a different matter since you need, constantly, loop on it to watch for data coming in. I've used multiple TX pins on the same PIC with no problems. You just need to use the STREAM to tell the compiler which TX pin you want to use for that particular print statement.

Ronald