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fastlink30
Joined: 14 May 2007
Posts: 33
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| Bootloader problem |
 Posted: Wed Jun 20, 2007 12:55 pm |
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i'm using this bootloader http://www.microchipc.com/PIC16bootload/
ccs 4.033
pic16f876
the problem is the continous reset of the pic, but only if i load the program with the booloader, if i load the program without the bootloader is all ok
the problem is the first 4 byte of code, if i try to see what happend in program memory i see the first lines for the bootloader correctly, but the first 4 lines of the program is disappeared overrides bt the bootlader.
is possible tell the compiler to not use the program memory from 0-4?
i tried with #org, but no luck |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jun 20, 2007 1:19 pm |
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Are you sure that's the problem ? I remember using this bootloader
years ago, and I don't recall that there was a problem with using
interrupt routines in the application code.
I do remember that the default state for the bootloader HEX file
(and their ASM source code) was to have LVP enabled. You need
to set your programmer to disable LVP when you program the bootloader
code into your PIC.
They even have a FAQ question on this. Though, for a 16F876 the
PGM pin is on pin B3.
| Quote: |
Q Why does my circuit keep resetting? Or not start up at all?
By default, if you have Low Voltage Programming (LVP) enabled, touching pin RB4 will reset the micro. In the worst case, a bad logic level on RB4 will keep the micro in reset. |
So, re-program the bootloader HEX file into the PIC, but disable LVP
in the Config bits options settings in your programmer. |
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Guest
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| Posted: Wed Jun 20, 2007 1:36 pm |
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yes, i know about LVP, is disabled.
the problem is present only if i use the bootloader, otherwise all goes fine
watchdog & related interrupt are disabled
these are the first line of the bootloader only
NOP
BSF 0xa,0x3
BSF 0xa,0x4
GOTO 0x732
program:
NOP
MOVLW 0x8
MOVWF 0xa
GOTO 0
MOVWF 0x7f
these are the lines after load the program with bootloader
NOP
BSF 0xa,0x3
BSF 0xa,0x4
GOTO 0x732
MOVWF 0x7f
then... the program start anyway, but randomly the pic reset & return code 27 from reset_cause()
i have inserted a printf("AA"); in the main procedure, sometimes i see text, sometimes nothing |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jun 20, 2007 1:47 pm |
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Post a little application program that demonstrates the problem.
Make the program be as small as possible. Make it be ten lines
of code, max. Post all #include, #use, #fuses statements. |
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fastlink30
Joined: 14 May 2007
Posts: 33
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| Posted: Thu Jun 21, 2007 1:18 am |
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| Code: |
#include <16F876.h>
//#device icd=false
#use delay(clock=10000000)
#use rs232(baud=19200,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)
#fuses NOWDT,HS, NOPUT, NOPROTECT, noBROWNOUT, NOLVP, NOCPD, NOWRT, NODEBUG
#org 0x1F00, 0x1FFF void loader16F876(void) {} //protect bootloader code for the 8k 16F876/7
void main()
{
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_spi(SPI_SS_DISABLED);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
//port_b_pullups(false);
printf("test");
while(TRUE) {
output_b(0);
output_low(pin_a0);
output_low(pin_a1);
output_low(pin_a2);
delay_ms(500);
output_b(0xff);
output_high(pin_a0);
output_high(pin_a1);
output_high(pin_a2);
delay_ms(500);
};
}
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Thu Jun 21, 2007 4:36 am |
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| Quote: | the problem is the first 4 byte of code, if i try to see what happend in program memory i see the first lines for the bootloader correctly, but the first 4 lines of the program is disappeared overrides bt the bootlader.
is possible tell the compiler to not use the program memory from 0-4?
i tried with #org, but no luck |
Some background information: on power up the program starts execution at address 0, this is the reset vector.
The bootloader is located at a high address in memory and should be the first thing to start at power up. This is achieved by placing a long jump at address 0 - 4.
Now there is a conflict between the bootloader and your application as they both want to use these same 4 bytes.
Your suggestion of forcing your program not to use the first 4 addresses is one way to solve this conflict but has the disadvantage that you need two different versions of your program, one for standalone use and one version for use in combination with a bootloader.
Shane Tolmie uses a different approach for the address conflict which has the advantage that you don't have to change a thing to your program whether being used with or without a bootloader. On program writing the bootloader monitors the addresses to program. If the address range 0-4 is detected these four bytes are written to a reserved memory space inside the bootloader.
What happens at power up now is that the first 4 bytes contain a jump instruction to the bootloader. The bootloader executes normally and when finished executes the 4 bytes it has saved on flash writing time.
A nice and clean mechanism with only two minor drawbacks:
1) In order for this to work the first four bytes generated by the compiler must always contain a long jump. This is true for most compilers including CCS.
2) This only works reliable on processors where the flash memory can be programmed with single bytes. True for (most) PIC16 processors, but the PIC18 is written in blocks of 64 or more bytes.
Summary: The first four bytes of your program in memory are changed on purpose.
I checked your program in v3.249 to start with a long jump in the first 4 locations, this is true. I don't have v4.033 so can't check this for you.
Check the troubleshouting list at the bootloader's website for what a long jump looks like in assembly. |
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fastlink30
Joined: 14 May 2007
Posts: 33
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| Posted: Thu Jun 21, 2007 5:43 am |
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first assembly lines of the program
| Code: |
CCS PCM C Compiler, Version 4.033, 6xxxx 21-giu-07 13.26
Filename: C:\main.lst
ROM used: 159 words (2%)
Largest free fragment is 2048
RAM used: 8 (2%) at main() level
9 (2%) worst case
Stack: 2 worst case (1 in main + 1 for interrupts)
*
0000: MOVLW 00
0001: MOVWF 0A
0002: GOTO 023
0003: NOP
.................... #include <16F876.h>
.................... //////// Standard Header file for the PIC16F876 device ////////////////
.................... #device PIC16F876
.................... #list
....................
.................... //#device icd=false
.................... #use delay(clock=10000000)
000E: MOVLW 22
000F: MOVWF 04
0010: BCF 03.7
0011: MOVF 00,W
0012: BTFSC 03.2
0013: GOTO 022
0014: MOVLW 03
0015: MOVWF 78
0016: CLRF 77
0017: DECFSZ 77,F
0018: GOTO 017
0019: DECFSZ 78,F
001A: GOTO 016
001B: MOVLW 3C
001C: MOVWF 77
001D: DECFSZ 77,F
001E: GOTO 01D
001F: GOTO 020
0020: DECFSZ 00,F
0021: GOTO 014
0022: RETLW 00
.................... #use rs232(baud=19200,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)
....................
.................... #fuses NOWDT,HS, NOPUT, NOPROTECT, noBROWNOUT, NOLVP, NOCPD, NOWRT, NODEBUG
.................... #org 0x1F00, 0x1FFF void loader16F876(void) {} //protect bootloader code for the 8k 16F876/7
*
1F00: RETLW 00
....................
.................... void main()
.................... {
*
0023: CLRF 04
0024: BCF 03.7
0025: MOVLW 1F
0026: ANDWF 03,F
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Jun 21, 2007 12:01 pm |
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Your code is doing a "long jump". It sets up PCLATH and then it does
a GOTO. I don't see a problem there.
But look at Shane's FAQ, here:
http://www.microchipc.com/PIC16bootload/PIC_bootloader_FAQ.php
In Section 4, he talks about the need for a long jump at the start.
He says:
| Quote: | | This section only applies to bootloader v6-52 and below. |
So he must be doing something different now, because he's up v9-50.
I would read his FAQ in detail.
What programmer are you using to put the bootloader code into the PIC ?
He says there's a problem if you use ICD2. He wants you re-assemble
the bootloader ASM code. |
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fastlink30
Joined: 14 May 2007
Posts: 33
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| Posted: Thu Jun 21, 2007 1:52 pm |
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i also read the faq, but no response
i'm using picstart+
i'm trying to make new bootloader to solve the problem |
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