[SOLVED] Serial Communication without UART

[TiagoRibeiro]

Hello,
I need start a project with pic18f4680, but he has only one USART. So my doubt is ... I can establish serial communication with other peripherals without using any function of the embedded pic as USART, SPI or I ² C?
How i can do this using C?

Thanks and waiting for the answer.

 

[barry]

You can write your own UART code. There's plenty of information on the web for the appropriate algorithms; there might even be some C-code out there. For the receive channel for example, you basically need to look for a start bit, read in 8 data bits, and then look for a stop bit. Easy-peazy.

But if you're using SPI or I2C, you can have multiple slaves on one bus, you don't need a separate UART for each device.

 

[TiagoRibeiro]

Thank you Barry, hear this is very good.. i will search in the web sample codes to do this in C

 

[TiagoRibeiro]

sorry but i dont find anything in the web..:-(..please show me some code sample or give links to see how do that...
thanks

 

[barry]

sorry but i dont find anything in the web..:-(..please show me some code sample or give links to see how do that...
thanks

I don't know how you search the web, but it took me 10 seconds to find these. Did actually search "UART C-code" ????


http://www.pjrc.com/teensy/uart.html
http://ww1.microchip.com/downloads/en/DeviceDoc/uartintc.readme.pdf
http://www.atmel.com/images/doc4346.pdf

 

[bigdogguru]

You also might find searching for "bitbang UART", "softUART" or "software UART" helpful.

Example: **broken link removed**


BigDog

 

[TiagoRibeiro]

thank you Bigdog,
This was the information I was looking for ..
I did not know find what I needed, now with your help it is possible
thanks again

 

[buffallo]

Yes, you can always do bit banging on the UART. I prefer writing such 'time-critical' routines in assembler though. Here are some good examples.

http://www.piclist.com/techref/microchip/rs232.htm

Regards

 

[TiagoRibeiro]

hello. I managed to make my software UART send a string.
But now I am unable to set the baud rate.
I searched for it and found many examples in asm ( delay functions TXbit, RXbit, Halfbit),
but I'm new in C language and is the only one I know, so I could not understand very well.
My doubt is I have to create routines for reading and writing bit by bit?
Can someone explain to me how to do this?

 

[barry]

The baud rate is simply controlled by how fast you toggle your bits. A simple timer (or timer routine) can take care of that.