generate baud clk signal

[vinniewryan]

I'm working with the MCP2122 'Serial to IR Encoder/Decoder' which has a 16XCLK input pin. I need to somehow generate a baud clk signal from a pin on my 16f684 to connect to the 16XCLK pin on the IR chip. Is there an easy way to do this? I read through the CCS Manual and found "SYNC_MASTER" under '#use RS232' configuration which says "Makes the RS232 line a synchronous master, making
the receive pin a clock out, and the data pin the data
in/out.", but when I tried to use configuration, I got an error "USE parameter value is out of range H/W USART required". Any suggestions?

Compiler V4.033

Thanks!
_________________
Vinnie Ryan

[PCM programmer]

Change your PIC to a 16F688. It's a 14-pin package, but it has a
hardware UART.

[vinniewryan]

I tried changing it to 16f688 but I'm still getting the same error..


This is my current config:

[PCM programmer]

You have to use the hardware pins, on C4 and C5. Check the pinout
diagram in the data sheet.

[vinniewryan]

Thanks PCM, I ordered some 16f688's today. I'm just trying to send ADC data from pic to pic via IR.
_________________
Vinnie Ryan

[FvM]

Unfortunately, your idea of using SYNC_MASTER mode doesn't work, I think.

IrDA needs to interface to a standard asynchronous UART, but must be supplied with a 16x bit clock, 153600 kHz for 9600 baud. With a PIC processor you need an additional timer output for the CLKx16, and the crystal frequency must allow it. E.g. a standard UART crystal like 3.686 MHz and multiples of it will work. If you don't have free timer resources, you can use a hardware frequency divider.

It should be noticed, than you can get IrDA chips from other vendors that have programmable baud generators, e.g. from Vishay.

More advanced processors like PIC24 have built-in IrDA interfaces.

[vinniewryan]

Thanks for the responses. After snooping around some more, I found a nifty document on Microchip's website titled "AN946" which provides all the info about generating the clock signal. A simple Timer2/CCP is all that's needed, generating a clock signal of 16X the desired baud rate.

Thanks again!
_________________
Vinnie Ryan