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Jerson,

Thanks for that advice. My problem is solved!

I can strongly recommend DIPtrace. It has excellent linked schematic and PCB layout functions. My only criticism would be that library function and designing custom components is over-complicated....

I have a serial connection from a MAX232 on my PIC board to an RS232 port on my PC. The data are used in a PC graphics and PIC-control application, using both the TX and RX lines.

Is there any...

Thanks for the response folks! I need to determine the EXACT frequency difference between the 2 channels, with frequencies in the 2MHz range. Both frequencies are changing continuously and are close...

I am using an 18F252 to count pulses into Timer0 and Timer1. The following is that part of the program for pulse counting into Timer0 for 100ms. Similar bits of code are used to control Timer1, as...

A big thanks again Mister_e. Indeed PortC.3 is analogue too. Sorry I missed that! The datasheet could be much clearer on issues like this or, as Nomad says, such pearls of port configuration wisdom...

Yes, I also did a search for ANSEL in the datsheet and found nothing of much use.

Although it works in this example, I am still unclear why ANSEL has any effect on the behaviour of LEDs on PortC.3...

Yup, that solved the problem!

Now I realy must try to understand what ANSEL actually does ....

A BIG thanks again to Mister_E!

I am using a 16F688, with internal clock enabled and only 2 port connections: to LED1 and LED2 on PortC.

This trivial program shows a problem I have found with the Port addressing:

...

Thanks for the speedy reply. I'll set the clock as you suggest.

With the MeLABS programmer the options are MCLR Pin Function = Reset or =Input Pin. Do you mean that the programmer should be...

Using tips from this forum my 16F188 program starts with the following code:

CMCON0=%0000111 'Comparators off. (NOTE: CMCON=7 does not work!)
OSCCON.3=1 'Use internal clock. NOTE: PIC...

I have had brilliant help from David Barker (Mecanique) and Charles Leo (MElabs) about this problem.

The solution is: In MicroCode Studio, click View - Compile And Program Options, then on the...

Yes, it is in the Microcode Studio combo box! I select this processor but the error appears!

Downloading this patch from Melabs and running it produces the same "Nothing to do" error message. I have had no problem compiling for other 16F*** and 18F*** PIC devices.

Thanks for the idea. I downloaded the patch program and ran it. However, the program replies:

"Nothing to do! The files are already updated."

So no solution I'm afraid!

I am using PBP V2.45 with Microcode Studio V2.45A. When I try to compile a program for the 16F688, Microcode Studio gives the error message:

Error in parameter "16F688"

This happens even when...

So it seems the average answer is YES XOR NO! Yup, if I accidentally re-assign an unused grounded pin as output and make it high then we have a problem. To be safe I'll tie all unused pins low via...

Sorry to go over old ground but I would appreciate some clarification. Various threads on this forum advise that all unused PIC pins should be configured as inputs and tied to ground to improve...

Yes, the program has a header line defining this oscillator frequency. The problem is solved as described before.

Thanks Melanie and Mister E for your kind advice - that was extremely helpful, as I will explain:

The crystal capacitors were actually 33 pF (!) but I changed them to 22pF and this improved the...

My circuit uses an 18F252 with 20MHz low profile crystal and 33nF capacitors for the clock. Power comes from a 7V bench supply, through a standard 7805 regulator and a MAX232 is used for serial to a...

Many thanks Sayzer and Charles for the final WORD (!). All clear now. I can now program a device until it (almost) bursts.

Thanks for the clues, Charles.

However, I am still a little bit confused. For example, suppose I change to a 16F676, which the data sheet says has "1024 Flash Words" of program space. Do these...

I need help in understanding how to select a PIC with the flash program memory size to accommodate my PBP-compiled programs.

For example, Microcode Studio tells me that one of my small programs...

Problem has been completely solved, as you suggested, by putting 0.1uF ceramic caps spanning the power supply lines to the PIC and the MAX232 on my breadboard. Thanks for the solution.
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