You can download a newer (actually two: 3.3.1 and 3.4.0) GCC from my webpage. I'm not a GCC expert, but I know they've fixed a serious ARM bugs in their IRQ handling around 3.3.0. You might be hitting it.
-- Regards, Andras Tantos
Hello group,
>
> I'm curently trying to get familiar with the ARM7 by building some
> example-projects for a LPC2106-controller. One such project is the
blinky_irq
example from Keil which should demonstrate the use of interrupts and of
the
LPC2xxx vectored interrupt controller. I'm using gcc-3.2.1 with binutils3.13.1
and newlib 1.11.0 . So far I had no problems with these tools and I was
able to
build and succesfully run some small demonstrator programs (without
interrupts)
on my LPC2106 board. For the blinky_irq example program I use the linker
script
and startup.s files (with adjustment for the Flash and RAM sizes of the
LPC2106)
that came with the source code from Keil's download area. Since the
program
didn't work I stripped it from all unnecessary functionality (main() is
> essentially an empty loop now) and simply let the timer ISR toggle a LED
on
GPIO24. That worked initially, but after some time (~ 3 minutes) the LED
stopped
toggling. I suspected that somwhere I'm loosing memory such that after
some time
I'm out of RAM. Hence, I took a look at the disassembled code and saw that
the
ISR is messing up the IRQ-mode stack pointer, loosing seven words each
time the
ISR is invoked.
> Since the ISR entry and exit codes are automatically generated by the
compiler I
suspect a bug in gcc. On the other hand, since this would be a very severe
> failure other users should have come across it, too. Does anybody of you
know
that error (i.e. should I change to another gcc version) or am I missing
> something (e.g. gcc options)?
> Below you'll find the build commands used, the sources of the program and
the
disassembled ISR code.
>
> TIA,
> Jens
>
> ------build commands-----------------------------
> $ make blinky_irq.hex
> arm-elf-as -mcpu=arm7tdmi -gstabs Startup.s -o Startup.o
> Startup.s: Assembler messages:
>
> arm-elf-gcc -c -g -I. -mcpu=arm7tdmi Time.c -o Time.o
> arm-elf-gcc -c -g -I. -mcpu=arm7tdmi Blinky.c -o Blinky.o
> arm-elf-gcc -T Flash.ld -nostartfiles -Lgcc -L. -o blinky_irq.elf
Startup.o
Time.o Blinky.o
> arm-elf-objcopy -I elf32-littlearm -O ihex blinky_irq.elf blinky_irq.hex
>
> ------sources------------------------------------
>
/***************************************************************************
***/
/**/
/* BLINKY.C: LED Flasher*/
/**/
/***************************************************************************
***/
> #include "LPC210x.h"
> #include "Timer.h"
>
> extern long volatile timeval; /*ISR counter variable*/
>
> void wait (void) { /* wait function, not used
actually */
unsigned long i;
>
> i = timeval;
> while ((i + 10) > timeval){
> }; /* wait 100ms */
> }
>
> int main (void) {
>
> IODIR = 0xFF000000; /* P1.31..24 defined as
Outputs */
> init_timer();
>
> while (1) { /* Loop forever */
> }
> }
>
>
/***************************************************************************
***/
/**/
/* TIME.C: Time Functions for 10Hz Clock Tick*/
/**/
/***************************************************************************
***/
> #include "LPC210x.h"
> #include "Timer.h"
>
> long volatile timeval; //counter for wait-routine
>
> void tc0 (void) __attribute__ ((interrupt)); // Generate Interrupt
>
> /* Setup the Timer Counter 0 Interrupt */
> void init_timer (void) {
> VICVectAddr0 = (unsigned long)tc0; // set interrupt vector
in 0
VICVectCntl0 = 0x20 | 4; // use it for Timer 0
Interrupt
VICIntEnable = 0x00000010; // Enable Timer0
Interrupt
> TIMER0_MR0 = 5898239; // 100mSec =
> (0.1*4*14,7456E6)-1 counts
> TIMER0_MCR = 3; // Interrupt and Reset on
MR0
TIMER0_TCR = 1; // Timer0 Enable*/
> }
>
>
> /* Timer Counter 0 Interrupt executes each 100ms @ 4x14,7456 MHz CPU Clock
void tc0 (void) {
> /* timeval++;*/
> if((IOPIN&0x01000000) == 0x00000000){
> IOSET = 0x01000000;
> }else{
> IOCLR = 0x01000000; //toggle GPIO24
> }
> TIMER0_IR = 1; // Clear interrupt flag
> VICVectAddr = 0; // Acknowledge Interrupt
> }
>
> -------------------disassebled ISR (with some
comments)---------------------
...
> 00000278 :
> ; --ip is stored on stack but not restored at ISR exit (see below)!!
> 278: e52dc004 str ip, [sp, -#4]!
> 27c: e1a0c00d mov ip, sp
> 280: e24ee004 sub lr, lr, #4 ; 0x4
> ; --write-back further decrements sp. This is not corrected on ISR exit!!
> ; --btw: why is pc stored on the stack anyway and why is ip with it's new
> ; --contents pushed onto the stack, too??
> 284: e92dd80c stmdb sp!, {r2, r3, fp, ip, lr, pc}
> 288: e24cb004 sub fp, ip, #4 ; 0x4
> 28c: e3a0320e mov r3, #-536870912 ; 0xe0000000
> 290: e283390a add r3, r3, #163840 ; 0x28000
> 294: e5933000 ldr r3, [r3]
> 298: e2033401 and r3, r3, #16777216 ; 0x1000000
> 29c: e3530000 cmp r3, #0 ; 0x0
> 2a0: 1a000004 bne 2b8
> 2a4: e3a0324e mov r3, #-536870908 ; 0xe0000004
> 2a8: e283390a add r3, r3, #163840 ; 0x28000
> 2ac: e3a02401 mov r2, #16777216 ; 0x1000000
> 2b0: e5832000 str r2, [r3]
> 2b4: ea000003 b 2c8
> 2b8: e3a032ce mov r3, #-536870900 ; 0xe000000c
> 2bc: e283390a add r3, r3, #163840 ; 0x28000
> 2c0: e3a02401 mov r2, #16777216 ; 0x1000000
> 2c4: e5832000 str r2, [r3]
> 2c8: e3a0320e mov r3, #-536870912 ; 0xe0000000
> 2cc: e2833901 add r3, r3, #16384 ; 0x4000
> 2d0: e3a02001 mov r2, #1 ; 0x1
> 2d4: e5832000 str r2, [r3]
> 2d8: e3e03d3f mvn r3, #4032 ; 0xfc0
> 2dc: e243300f sub r3, r3, #15 ; 0xf
> 2e0: e3a02000 mov r2, #0 ; 0x0
> 2e4: e5832000 str r2, [r3]
> ; --registers are restored, pc is loaded with (lr-4) and cpsr is restored
> ; --so this causes a return to the user code. But ip is not restored to
it's
; --initial value but to the value that was assigned to ip after it was
saved
; --on the stack. And, sp is not restored to it's initial value!!
> 2e8: e95b980c ldmdb fp, {r2, r3, fp, ip, pc}^ ;
>
>
>