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Re: [avr-gcc-list] Bootloader question

From: Eric Pasquier
Subject: Re: [avr-gcc-list] Bootloader question
Date: Fri, 14 Dec 2007 10:10:29 +0100

Did you check that your treatment is not too long and that you do not have a problem with nested interrupt ?
How is your interrupt treatment ?
Is it possible to set the timer frequency differently to avoid the "mod3 % 40" test ?

Eric Pasquier

----- Original Message ----- From: "Scott Morken" <address@hidden>
To: <address@hidden>
Sent: Friday, December 14, 2007 9:26 AM
Subject: [avr-gcc-list] Bootloader question


I have an application that jumps to the bootloader using this function (it's a slightly modified avr109 bootloader made by atmel): void (*funcptr)( void ) = (void *)0x3800; // Set up function pointer to the bootloader start.

I call it when a command is sent over the serial port, making this code run:
wdt_disable();//disable watchdog
cli();//disable all interrupts
for(counter = 0; counter<20000; counter ++)
                      funcptr();//goto bootloader

It has been working great until some code was added to my application. Now it will not enter the bootloader properly when I send the command. I suspect the chip is crashing before it gets to the funcptr(); line. I have narrowed down the code to about 10 lines in a timer overflow interrupt, when I comment it out it works fine. Here are the suspect lines. All of the arrays are floats and the capital letter variables are integers:

if ((mod3 % 40) == 0) //we are here 25x per second, for 25Hz sampling rate filter code

      //1st order, 7Hz -3dB lowpass, 25Hz sampling filter
       xv4[0] = xv4[1];
       xv4[1] = (float)GEN_V_DIV_ADC / 1.827271946;

       yv4[0] = yv4[1];
       yv4[1] = (xv4[0] + xv4[1]) + (-0.0945278312 * yv4[0]);

       GEN_V_DIV_ADC_FILTERED = yv4[1];

       //1st order, 3Hz -3dB lowpass, 25Hz sampling filter
       xv5[0] = xv5[1];
       xv5[1] = (float)SUPERCAP_DIV_ADC / 3.525711689;

       yv5[0] = yv5[1];
       yv5[1] = (xv5[0] + xv5[1]) + (0.4327386423 * yv5[0]);



Does anyone know of a reason why it would crash?


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