I will try to make this question as short as possible. I'm making a "quiz box" that displays the first two of any 20 players that buzz in. I'm using a pic16f77. The program scans 20 ports (buttons) and displays the first two numbers (1-20) on four single digit 7-segment LED displays via a display driver. Also, a speaker buzzes after the first player has buzzed in. Everything works great except for this one "little" bug. When I first turn on the power, the displays get set to zero's and the program starts scanning the buttons. If I first push a button in the teens (10-19) the first digit is always wrong. For example, in stead of displaying 12, it displays 32 or 72. Next I push a button (1-9) and it displays correctly. If I reset the program and push the same buttons in the same order, the problem occurs again. However, if I reset the program and first push a button (1-9), then push a button (10-20), it displays correctly and every time thereafter until the power switch is toggled off then on again. The same thing happens when I turn the power on and first press a button (1-9) then a button (10-19) - it displays incorrectly until I reverse the order. I push one (10-19) then one (1-9) and everything works fine. So, everytime I want to use it, I have to "intialize" it to get past the bug before it will work right. This problem is very perplexing. The program debugs fine. There is absolutely no reason for the mc to be spitting out these goofy numbers. Does anyone have any idea, hardware or software, what could be causing this problem? I hope this wasn't too confusing. Thanks in advance. Steve
pic16f77 acting goofy
Started by ●December 16, 2004
Reply by ●December 16, 20042004-12-16
> So, everytime I want to use it, I have to "intialize" it to get past > the bug before it will work right. This problem is very perplexing. > The program debugs fine. There is absolutely no reason for the mc to > be spitting out these goofy numbers. Does anyone have any idea, > hardware or software, what could be causing this problem? I hope this > wasn't too confusing. Thanks in advance.This problem is best fixed by single stepping in an emulator or in a simulator. I would be surprised if it was not a S/W problem. -- Best Regards, Ulf Samuelsson ulf@a-t-m-e-l.com This is a personal view which may or may not be share by my Employer Atmel Nordic AB
Reply by ●December 16, 20042004-12-16
mcki0127@hotmail.com wrote:> I will try to make this question as short as possible. I'm making a > "quiz box" that displays the first two of any 20 players that buzz in. > I'm using a pic16f77. The program scans 20 ports (buttons) and > displays the first two numbers (1-20) on four single digit 7-segment > LED displays via a display driver. Also, a speaker buzzes after the > first player has buzzed in. Everything works great except for this one > "little" bug. > > When I first turn on the power, the displays get set to zero's and the > program starts scanning the buttons. If I first push a button in the > teens (10-19) the first digit is always wrong. For example, in stead > of displaying 12, it displays 32 or 72. Next I push a button (1-9) and > it displays correctly. If I reset the program and push the same > buttons in the same order, the problem occurs again. However, if I > reset the program and first push a button (1-9), then push a button > (10-20), it displays correctly and every time thereafter until the > power switch is toggled off then on again. > > The same thing happens when I turn the power on and first press a > button (1-9) then a button (10-19) - it displays incorrectly until I > reverse the order. I push one (10-19) then one (1-9) and everything > works fine. > > So, everytime I want to use it, I have to "intialize" it to get past > the bug before it will work right. This problem is very perplexing. > The program debugs fine. There is absolutely no reason for the mc to > be spitting out these goofy numbers. Does anyone have any idea, > hardware or software, what could be causing this problem? I hope this > wasn't too confusing. Thanks in advance. > > SteveIt sounds like you have forgotten to initialize a register. Namely, the one that holds the most-significant digit. Check your initialization code. Noel
Reply by ●December 16, 20042004-12-16
mcki0127@hotmail.com wrote: <snip>> > When I first turn on the power, the displays get set to zero's and the > program starts scanning the buttons. If I first push a button in the > teens (10-19) the first digit is always wrong. For example, in stead > of displaying 12, it displays 32 or 72. Next I push a button (1-9) and > it displays correctly. If I reset the program and push the same > buttons in the same order, the problem occurs again. However, if I > reset the program and first push a button (1-9), then push a button > (10-20), it displays correctly and every time thereafter until the > power switch is toggled off then on again. > > The same thing happens when I turn the power on and first press a > button (1-9) then a button (10-19) - it displays incorrectly until I > reverse the order. I push one (10-19) then one (1-9) and everything > works fine. > > So, everytime I want to use it, I have to "intialize" it to get past > the bug before it will work right. This problem is very perplexing. > The program debugs fine.?!> There is absolutely no reason for the mc to > be spitting out these goofy numbers.Well, there clearly must be a reason - it sounds very predictable: you have just not found the reason, yet.> Does anyone have any idea, > hardware or software, what could be causing this problem?You have enough info in the interaction to start the debug process. When a system is path dependent, but does have the ability to behave correctly, it points to a software initialise problem. Look for different variable handling, in your 'works OK' path, from the 'fails' path. It is good practice to clear all variable RAM on reset, in a 80c51 this takes 6 bytes of code - and can save a lot of other variable inits. You then code, so all 'safe defaults' are the 00 or FALSE values. -jg
Reply by ●December 16, 20042004-12-16
I did something similar with an Atmel AT90S2313 processor. Code works fine and is in use, I believe. Circuit schematics and box and source code etc. are all right here if that helps, too. Here's some of the header comments: ; This program operates a Jeopardy or college-bowl kind of game device ; where the first person to press a switch is selected, locking out the ; others. Eight contestants are supported, each by direct connection to ; an input pin. An LED lights up to indicate which switch (contestant) ; is pressed first and the rest of the contestants are then locked out. ; The buzzer emits a short burst, as well, to signal that a contestant ; has pressed their button. Not 20 buttons in this case, but extending it would be easy. In any case, the basic ideas in the code are there, too. Jon
Reply by ●December 16, 20042004-12-16
"Jim Granville" <no.spam@designtools.co.nz> wrote> When a system is path dependent, but does have the ability to behave > correctly, it points to a software initialise problem. > It is good practice to clear all variable RAM on resetZeroing ram is always a good idea at the start, but I find it most useful in debugging because it makes a memory dump easier to interpret. I develop with RAM zeroed, and then verify operation with ram set to 0FFH. Variables that are not explicitly initialized are verboten under all circumstances. If you are having weird problems then setting memory to all 1's can often make the source of the problem stand out like a sore thumb (or stamp). -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/
Reply by ●December 17, 20042004-12-17
Wow, thanks for all the help and suggestions. I'm using MPLAB IDE v6.61 with MPLAB SIM. I can step through the program and use the pin stimulus feature to check the different scenarios. The program seems to work fine, storing all the correct values in each register. I've declared two variables that keep track of the buttons pushed: flag1 and flag2. I intitialize these registers by clrf flag1 clrf flag2 Is this sufficient? In a later subroutine, those hex numbers get split into dig1a, dig1b, dig2a, and dig2b to be sent to the display driver. They are initialized the same way. I'm not exactly sure what is meant by the RAM. Is that the block of general purpose registers used to store all the variables? If that's the case, then mine starts at 020H. If I write all 0's (or 1's) to these registers, should I then run the program to the point where it's messing up, and then do a memory dump to see what each variable holds? Jon, I would like to take a look at your box design, but there doesn't seem to be a link with your message :=) Steve
Reply by ●December 17, 20042004-12-17
mcki0127@hotmail.com wrote:> Wow, thanks for all the help and suggestions. I'm using MPLAB IDE > v6.61 with MPLAB SIM. I can step through the program and use the pin > stimulus feature to check the different scenarios. The program seems > to work fine, storing all the correct values in each register. > > I've declared two variables that keep track of the buttons pushed: > flag1 and flag2. I intitialize these registers by > > clrf flag1 > clrf flag2 > > Is this sufficient? In a later subroutine, those hex numbers get split > into dig1a, dig1b, dig2a, and dig2b to be sent to the display driver. > They are initialized the same way. I'm not exactly sure what is meant > by the RAM. Is that the block of general purpose registers used to > store all the variables? If that's the case, then mine starts at 020H. > If I write all 0's (or 1's) to these registers, should I then run the > program to the point where it's messing up, and then do a memory dump > to see what each variable holds? > > Jon, I would like to take a look at your box design, but there doesn't > seem to be a link with your message :=) > > SteveDuring your initialization, did you setup your PORTs to have the correct default value? This is usually done just before a write to TRIS. It is just as important as properly initializing your variables. Noel
Reply by ●December 17, 20042004-12-17
Reply by ●December 17, 20042004-12-17
On 17 Dec 2004 09:33:19 -0800, the renowned mcki0127@hotmail.com wrote:>Yes, I also clear all the ports before writing to the TRIS registers. >SteveAssuming your program is written in assembler, this sounds like the kind of PIC bug that results from forgetting a bank select instruction somewhere. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com