Post by thread:[PIC]: 18C452 reset problems

I am writing my code in C using the MPLAB-C18 compiler. As a test, and to learn how the PIC works, I have written a small program that runs in a loop, reading a voltage from the internal A/D converter, flashes a LED (connected to PortB) at different rates depending on the voltage that was read, and then outputs (via TX on port C) the digital value over a serial connection to a computer. The LED flashes and data is output over the serial port (although the data is incorrect), but after the program runs for approximately 3 seconds, the PIC resets, which I believe may attribute to the bad serial data. I have the watchdog timer set to OFF when I program the PIC, and i'm running at 4 MHz. I tried taking the A/D and serial communications out of the loop, so that all it does is set and clear the TRIS bit and PORT bit, and it still resets after the same amount of time. Anyone have any ideas of what i could be doing incorrectly? If someone is willing to help, I can send you my code as well... Thanks! ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the sender immediately. This footnote also confirms that this email message has been swept by MIMEsweeper and Symantec Norton AntiVirus for the presence of computer viruses. ********************************************************************** -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

Could it possibly be a stack underflow reset? In assembly, you would have to check that every CALL has a RETURN. C18 *should* handle that automatically, but you know how m-chip software is. ;) Try troubleshooting by disabling stack underflow reset. If this is the problem, you'll probably see some REALLY strange results when you disable it, but at least you'll know where the problem lies. Jen -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

Correcting/clarifying myself... Each call should have exactly one return. If there's an EXTRA return somewhere, that would cause the reset. The C compiler may or may not scream at the extra return; if it doesn't, guess what? :) I'm not sure if that helps or makes things worse, but I'll take a stab at it anyway. Jen {Quote hidden}> Could it possibly be a stack underflow reset? In assembly, > you would have > to check that every CALL has a RETURN. C18 *should* handle that > automatically, but you know how m-chip software is. ;) Try > troubleshooting > by disabling stack underflow reset. If this is the problem, > you'll probably > see some REALLY strange results when you disable it, but at > least you'll > know where the problem lies. > > Jen > > -- > http://www.piclist.com hint: To leave the PICList > .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu > > -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu

On Wed, 10 Jul 2002 @spam@James.HyslopKILLspamBMWMC.COM wrote: >+5 through a 4.7K resistor. Have also tried connecting a .1uF cap between >MCLR and GND but doesn't seem to make a difference. The program loop >actually starts runnning, but will only loop a couple of times before >resetting. This sounds like the watchdog is running and you're not clearing it. Peter -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu

Is it possible that the watchdog could start running even if I disabled it in the configuration when I programmed the PIC? I took out all of the loops, and the chip still resets after about 3 seconds. Going to try assembly next or else try another chip. Also, I am currently turning on and off an LED via the below code: I am using the MPLAB C18 compiler. //set RB1 as output TRISBbits.TRISB1=0; //turn on LED on RB1 LATBbits.LATB1 = 0; PORTBbits.RB1 = 0; //wait a little Delay10KTCYx(1); //turn off LED on RB1 LATBbits.LATB1 = 1; PORTBbits.RB1 = 1; The guide was not very specific on how this should really be done. If there is a better or more efficient way of doing this, could someone please offer advice? Thanks again! {Original Message removed}

Hello, you miss a loop and another delay. A. while(1) { //set RB1 as output TRISBbits.TRISB1=0; //turn on LED on RB1 LATBbits.LATB1 = 0; PORTBbits.RB1 = 0; //wait a little Delay10KTCYx(1); //turn off LED on RB1 LATBbits.LATB1 = 1; PORTBbits.RB1 = 1; Delay(); }; _________________________________________________________________ Join the world s largest e-mail service with MSN Hotmail. http://www.hotmail.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads