PIC Help

All bets are off if the chip's damaged. Generally I find that they just won't read or program, the programmer gives an error.

The 20P should work fine in place of the 04P, the number refers to the max clock speed (MHz).

Great i'll grab one tomorrow. Thanks for the quick reply, and fingers crossed that's all there is wrong.

Usually nothing at all. Most good programmers will give you an error as they attempt to verify the data written.

The -20P is identical, just a higher rated clock speed. But you can't substitute say a 16F628A chip which is the same pinout as the 16F84A.

16F84 is also slightly different from 16F84A

Dave.

OK i manged to make it to jaycar before they closed. I got a 16F84A-20/P to replace the 16F84A-04/P.

Programmed it up, but in the project, it doesn't work at all.

With the original PIC, all the lights come on, but nothing works. With the new one, none of the lights come on at all.

The programmer i have does verify the program after it has written to the chip. Now, the weird thing is that sometimes the programmer doesn't read the data off the chip properly. I'm not sure if this is a software glitch, or a hardware glitch or that the "new" PIC i got is faulty. I am also assuming that the code i downloaded from the silicon chip website in the HEX file is correct...

I got it to program, verify more than once, but sometimes it brings up the wrong data like there's a bad connection or something, but it does program and verify, i just have to remove/reinsert it a few times into the ZIF.

Tried multiple times inserting into the socket in the project and it doesn't seem to want to work. Bah so frustrating. Not worth another $10 i don't think.

Thanks for the help.

Unlikely that the chip would have been faulty on receipt. It could have been damaged by residual faults in the tacho when you inserted it, something like a regulator fault that's put 12 volts onto it. If you want to proceed, the first thing to do is to load a simple test program such as an LED flasher into the PIC, and verify that the processor functions autonomously, ie. with just a 5V PSU and a 47n cap across the supply. That will also prove your programming setup.

Besides being very frustrating, inserting PICs into suspect hardware is a fine way to run down your stock of chips, you really need to first do everything you can to verify that the rest of the tacho is OK. For starters, check that all the socket voltages are between 0 and 5V without the chip inserted. Good luck.

messagenews: snipped-for-privacy@g3g2000pre.googlegroups.com...

It should be correct, but not all HEX files contain the appropriate configuration fuse info required to set the PIC up correctly (oscillator source, interrupts, watchdog timer etc). It all depends on if the original programmer included those (a good programmer would have). You can check and set them manually in the programmer, but you have to know what they are originally supposed to be.

Unlikely to be the chip at fault, most likely a dodgy universal programmer. What brand and model is it?

Dave.

Thanks Bruce,

First check i did was make sure regulation at Pin 4 and 14 was at +5V and it was (5.015). These were listed as the recommended test points in the initial power up procedure in the manual for the kit to make sure it was OK before inserting the PIC for the first time. Its possible other areas have been damaged for sure and i'll look into that closer. There is no specific physical damage that i can see at this stage, but of course there doesn't need to be burn marks for a component to have failed.

I'll start to have a look around for a simple program like an LED flasher to program to it. This is my first time working with a PIC so its all fairly foreign to me, but research always clears away the fog, and hopefuly learn something new along the way.

Thanks again.

Thanks Dave,

I also have the ASM source here from the Siliconchip website (But no tools to re-compile it, nor do i know how at this point).

When programming the chip there are 3 separate tabs in the software that can be separately modified "code memory" "data memory" and "user ID memory". When programming i had to program each of the 3 window separately to completely program the chip as per the whole hex file. Programming juts the code memory (as i initially did) made not changes to the data memory which i initially thought was the reason it didn't work.

The programmer is one of these, it ain't a cheap one (compared to some ebay $15 jobs) so i hope its not considered 'too' dodgy. Although obviously its not a $2000 one that RS sells. lol. I've had no issues with it for programming the AM29F010 chips that i most commonly use, but its barely done any work really.

Thanks.

The MPLAB tools are free from the Microchip website. These will allow you to write and assemble programs for PIC microcontrollers, as well as debug them in an internal simulator before programming your target device.

Is the clock internal (4MHz) or an external one?

messagenews: snipped-for-privacy@40g2000prx.googlegroups.com...

I just checked the ASM source code. The config bits are set in the code by this line near the top: " __config _XT_OSC & _WDT_OFF & _PWRTE_ON"

That means the correct (and required) config fuse settings will be automatically compiled into the .HEX file. So there should be no worries there, you should be able to just load the HEX file and program. But before you program check the chip config settings in your programmer software, they should have been set to "XT_OSC" ON and "WDT" set to OFF.

Ah yes, another "Willem" programmer knock-off. You are right in that it's not "too dodgy", but is still a low end non-professional programmer. Problems are to be expected. If your chip doesn't program and read reliably in that then it's 99% certain to be the programmer. The chips are usually go/no-go.

Dave.

Just downloaded it and will give it a shot. There is an external clock,

4.000mhz.

messagenews: snipped-for-privacy@40g2000prx.googlegroups.com...

I also noticed the source code is designed for the old 16F84, not the

16F84A. It's defined in these lines here: list P=16F84 #include "p16f84.inc"

I can't remember the exact difference between them but I think there were some differences. Doesn't explain your programmer going a bit flaky though.

Dave.

The original kit may have been designed for that and they have simply not updated the code on the website although providing a later model PIC with the currently packaged parts. date code on the sticker on the pic indicates middle of 2005 it was programmed.

I feel a little silly realising this now, however while researching this stuff i have found that when a chip is set for code protection, it will read all 0's, which is exactly what is happening to the original PIC. so maybe its not "dead" afterall... there is an LM358 opamp on the board too which i'm going to replace as its a cheap part just in case as it is in the path of components that were damaged. Going to pickup a few bits and pieces to play with the PIC i got anyways, make sure the program stuff is working etc.

Thanks.

messagenews: snipped-for-privacy@u18g2000pro.googlegroups.com...

Ah yes, it does that! Simply disable to write protect bit in the programmer settings and try again. The code itself doesn't know nor care if the write protect bit is on or off. Good programmers will write all the bits, verify them once, and *then* program the write protect bit, making further readback or verification impossible. But you can always erase and program over it again.

Dave.

"What The" schreef in bericht news:jraal.9858$ snipped-for-privacy@news-server.bigpond.net.au...

You'd make sure that your programmer is set to the chip you're programming. There are differences between original and -A devices that may cause problems. Most programmers I know, are able to identify the inserted PIC. There are known differences between the programming specifications of the

16F628 and the 16F628A. I'm not sure about the 16F84.

If you have the source code, it may be worthwhile to convert to the

16F628(A). It's a cheaper chip and not absolete.

petrus bitbyter

Thanks petrus,

Yes the programmer won't let you do any operation until you have selected the chip from the listings and it then shows a diagram of where it should be placed in the ZIF to be properly read and whether or not an adapter is required for the chip selected.

That's a possible solution to change the chip but at this point in time i'm not sure if the problem is the PIC now. I have repalced the OP amp as well as that is on the input signal path and the (failure to) function is the same. I'm at the point now where it could be one of the transistors or another small discrete component like a zener that is broken and to be honest, i don't have the will to tear the thing apart to fix it and sell it off. I was hoping it was an easy/cheap fix.

Thanks.

What The wrote: ...

Do you want to get rid of it as it is? Let me know ttp105 at yahoo.com.au if you want.

Tom