16f688 uart problems still

leem · Joined: 16 Jan 2008 Posts: 7

Hello,
I have been trying to program a 16f688 with the hardware uart enabled however It doesn't seem to work. I have looked all over this forum and noticed a mention that v3.2 of the compiler was screwed up and did not work. My question is what version of the compiler did they finally fix this or haven't they. I have tried it in version 4.038 and it seems to not work. If I just use pins A4 and A5 for a software uart, that works.

Thanks.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Try the following simple test program. lt uses the hardware UART pins.
See if it works.

leem · Joined: 16 Jan 2008 Posts: 7

Thanks PCM. That worked. I guess I should have actually programmed a pic before I posted. I was running the code in the oshonsoft Pic Simulator and it didn't display anything. I tried your example and it also didn't work in the simulator either, but works fine if I program a chip. hmmm 2nd possible bug I have found in that software.

Thanks again

Gigalite · Guest

This code doesn't seem to work at a 20MHz oscillator. Is there a #FUSES missing? Have somebody worked with the 16f688 uart at 20MHz that can provide a working code?

Ttelmah · Guest

Some obvious ones:
1) Internal RC oscillator, 8MHz max. - need to use 'HS' for an external 20MHz crystal, instead of INTRC_IO.
2) Voltage. 4.5v _minimum_, for 20MHz operation, as against 3v, for 8MHz operation.

Best Wishes