Issues when programming PIC16F877A

[jonw0224]

I think I messed up a PIC16F877A with my programmer. I was building a circuit mixed analog and digital that included a PIC16F877A. I powered up the circuit to test the analog part of the circuit on my breadboard, but at the same time powered up the PIC16F877A.

RB6, RB7, and MCLR were floating. I'm pretty sure RB3 was hooked to an input so it was floating also. Later, I couldn't program the chip.

The programmer I am using is a "Classic Tait" which I built. It still programs a PIC16F84A just fine. I have never programmed a PIC16F877A with my programmer before, but I was under the impression that it was programmed in the same way as the PIC16F84A (I'm using high voltage programming). Is that correct?

Could I have damaged the chip by floating the programming pins?

I'm probably going to buy another PIC16F877A just to make sure, but I wanted to see if any of you had any input...

 

[btbass]

I've plugged them in the wrong way round on a couple of occasions, the bloody thing got realy hot!
But it still worked ok once I plugged it in correctly.
They are pretty hardy chips, I doubt if a floating input would bother it much?

 

[hill]

mclr pic16f877a

I think I messed up a PIC16F877A with my programmer. I was building a circuit mixed analog and digital that included a PIC16F877A. I powered up the circuit to test the analog part of the circuit on my breadboard, but at the same time powered up the PIC16F877A.

RB6, RB7, and MCLR were floating. I'm pretty sure RB3 was hooked to an input so it was floating also. Later, I couldn't program the chip.

The programmer I am using is a "Classic Tait" which I built. It still programs a PIC16F84A just fine. I have never programmed a PIC16F877A with my programmer before, but I was under the impression that it was programmed in the same way as the PIC16F84A (I'm using high voltage programming). Is that correct?

Could I have damaged the chip by floating the programming pins?

I'm probably going to buy another PIC16F877A just to make sure, but I wanted to see if any of you had any input...

You have to make sure that the programmer software you're using really supports A part. As far as I know, the A part uses different programming algorithm than non-A part.

 

[metal]

pic16f877 winpic

Hello

jonw0224

I think you messed up with a connection or so, try to make sure your connections are right and tight.



btbass:

I agree with you, I have bothered PIC16F84A many times, it seems that it doesn't want to get damaged, some times I don't put it in the socket the right way, it gets hot, burns my finger, when it gets cold, I put it the right way, and program it !!

 

[fuzzzy]

pic16f876 mclr floating

Hi,

I can say, according to my experince that Programming A devices is harder than others. so I think you have problems with your programmer.

I used a Programmer to program Pic16f84A and it worked pretty good.
Then I tryed to program PIC16F876A with the same programmer but I couldnt manage it. I had to change my chip in PIC16F876 (without A) that can be programmed easily by my programmer.

I suggest you to change programmer. Try to use JDM properly modifyed to program A devices.
You can see schematic in this link:

 

[jonw0224]

winpic pic16f877

I've done a little more testing and here's what I found:

The input impedance on the MCLR pin is around 100 ohms. My programmer pulls the voltage up with a 3906 PNP transistor, so it's getting around 4-5V on MCLR instead of the full 12V. Still, the MCLR pin should have a much higher impedance (the 16F84A impedance on MCLR is out of range on my DVM). It is possible I supplied 12V to VSS while testing the other part of my circuit. Mistakes happen. It is also possible that I got a bad chip.

Still, the points you bring up may lead me to believe that my programmer won't work with this new chip. While I wait on my chip, I have some programming application notes from Microchip I need to read. Thanks.

 

[metal]

picall fpp

Hello

I think you got a bad chip, I think so because MCLR generally consumes a couple of 100uA as I remeber, also you can't measre the impedance of MCLR of the PIC.

Regards

 

[Jack// ani]

pic16f877 work mclr

Yep, MCLR pins takes only a few uA current, it needs only a 13V voltage to put it into programming mode until you are using LVP mode. Appears that yous chip is dead!!

Good luck

 

[jonw0224]

prog test pic16f877a

You have to make sure that the programmer software you're using really supports A part. As far as I know, the A part uses different programming algorithm than non-A part.

It turns out hill is correct. My programmer software (FPP from David Tait) doesn't support the A part and the PIC16F87XA has a different programming algorithm than the PIC16F87X. So even if my chip worked (which at first it probably did) my programmer software wouldn't have. The PIC16F84 and the PIC16F84A have the same programming algorithm. That's why I could program a PIC16F84A. I'm going to migrate to IC-PROG. It should support my programmer, but I haven't tried it out yet. Thanks again.

 

[metal]

pic16f87xa mclr

Hello

Hint:

If you have already built Standard tait programmer, then, when you use ICProg, all you have to do is invert Vdd and Vpp if you are using SN7407. If you are using SN7406, then I recommend you to go for SN7407

Regards

 

[jonw0224]

pic programmer 2n3906 sn7406

Hi guys, thanks for all your help, but I've got one more question...

I got a new PIC16F877 and PIC16F877A. I can program and verify the PIC16F877 with IC-PROG and my programmer. However, I appear to be able to program the PIC16F877A but NOT verify it (I loaded a test program to blink an LED once a second and it works, but IC-PROG won't verify the chip). Has anyone else had this experience?

 

[master_slave]

programmer sn7406

I think your programmer is the problem. I can't say much, but I had problems with Tait's programmer when it comes to verify failed. I use the programmer circuit from the Olimex ICSP programmer and IC-Prog and both never failed, well, in my case.

 

[metal]

tait classic verify failed

Hello jonw0224
I got exactly the same problem today, when trying to program PIC16F877A with ICProg, and verify it, I get ann error, trying to read the PIC gives me all 3FFF except for the first location which is filled with 3ef8.

I see that there is nothing wrong with the hardware, its the software problem, PICALL, EPICWIN, ICPROG, WINPICPROG, and WINPIC all failed to program PIC16F877A.

I tried to use WINPIC800 and it woked perfectly, so, this will solve the problem at the mean time.

Good luck

 

[comsians]

jonw0224

There a problem came with me by using PIC16F877

My two controllers are out of orders by programming it through proper professional programmer

i think programming 16f84 is easy but a problem came in 16f877

 

[jonw0224]

PIC16F877 Problem

I see there has been some recent activity on this thread.

I found that if I set ICPROG to verify DURING programming (instead of program and then verify) that it programs and verifies the PIC16F877A correctly.

Unfortunately, ICPROG won't read my code back to me :-( I see similar things that metal sees when I try to read.

 

[metal]

Re: PIC16F877 Problem

Hello jonw0224

I did avoid mentioning this to let you go with WinPIC800, I see you discovered this your self now, I noticed that ICProg won't read PIC16F877A, but if you configure it to verifiy while programming only, then things will stay fine.

Any way, I did not mention this because I had WinPIC800 programming and verifying during programming and verifying after programming, that will be much better chioce indeed.

Also another unforeseen issue to you jonw0224, if you still facing problems, you better ground RB3 to avoid unexpected behaviour, please download the datasheets, and read in chapter 14 about special CPU stuff, go for LVP stuff and you will read that you bettter ground RB3 if you want high voltage programming.

Good Luck

 

[jonw0224]

PIC16F877 Problem

metal-

Thanks again for all the help. I have been grounding RB3, thanks for the advise. I downloaded WinPIC800 and it works nicely.

-jonw0224

 

[metal]

Re: PIC16F877 Problem

Hello

I am glad to hear that you did it

Good luck