Lpc2000

--- In lpc2000@yahoogroups.com, "Joel Winarske" <joelw@...> wrote:
>
> > I am not able to understand why
> > 
> > T0MR0 += L_COMPAREMATCH;
> > 
> > doesn't work!!! I use other micro, such as Texas MSP430, and this
> > implementation work well! Is there a bug in micro or I have to do
> > something before read/write T0MR0???
> 
> Hmm, I'm doing this on a LPC2148 with no problem:
> 
> T0MR0 += SAMPLE_INTERVAL;
> 
> Did you check the assembler output?
> 
> 
> Joel
>

Source code is:
void vPortPreemptiveTick( void )
{
	#if portPRESCALE_VALUE != 0
		#define L_COMPAREMATCH (configCPU_CLOCK_HZ / 
configTICK_RATE_HZ) / portPRESCALE_VALUE
	#else
		#define L_COMPAREMATCH (configCPU_CLOCK_HZ / 
configTICK_RATE_HZ)
	#endif

	if (T0IR & BIT(0))
	{

    T0MR0 += L_COMPAREMATCH;

		/* Increment the tick counter. */
		vTaskIncrementTick();

		/* The new tick value might unblock a task.  Ensure 
the highest task that
		is ready to execute is the task that will execute 
when the tick ISR
		exits. */
		vTaskSwitchContext();

		/* Ready for the next interrupt. */
		T0IR = portTIMER_MATCH_ISR_BIT;
	}
	extern void vTmr0Cr0_Isr(void);
	if (T0IR & BIT(4))
	{
		vTmr0Cr0_Isr();
		T0IR = BIT(4);
	}
	VICVectAddr = portCLEAR_VIC_INTERRUPT;
}

L_COMPAREMATCH is equal to 0x1770. Checking assembler code, it seems 
correct.

Assembler generated code is:
vPortPreemptiveTick:
        PUSH        {LR}
        CFI ?RET Frame(CFA, -4)
        CFI CFA R13+4
        LDR         R0,??vPortPreemptiveTick_0  ;; 0xe0004000
        LDR         R0,[R0, #+0]
        LSL         R0,R0,#+0x1F
        BPL         ??vPortPreemptiveTick_1
        LDR         R0,??DataTable4    ;; 0xe0004018
        LDR         R1,??DataTable4    ;; 0xe0004018
        LDR         R1,[R1, #+0]
        LDR         R2,??DataTable3    ;; 0x1770
        ADD         R1,R1,R2
        STR         R1,[R0, #+0]
        _BLF        vTaskIncrementTick,vTaskIncrementTick??rT
        _BLF        vTaskSwitchContext,vTaskSwitchContext??rT
        LDR         R0,??vPortPreemptiveTick_0  ;; 0xe0004000
        MOV         R1,#+0x1
        STR         R1,[R0, #+0]
??vPortPreemptiveTick_1:
        LDR         R0,??vPortPreemptiveTick_0  ;; 0xe0004000
        LDR         R0,[R0, #+0]
        LSL         R0,R0,#+0x1B
        BPL         ??vPortPreemptiveTick_2
        _BLF        vTmr0Cr0_Isr,vTmr0Cr0_Isr??rT
        LDR         R0,??vPortPreemptiveTick_0  ;; 0xe0004000
        MOV         R1,#+0x10
        STR         R1,[R0, #+0]
??vPortPreemptiveTick_2:
        LDR         R0,??vPortPreemptiveTick_0+0x4  ;; 0xfffff030
        MOV         R1,#+0
        STR         R1,[R0, #+0]
        POP         {R0}
        BX          R0                 ;; return
        DATA
??vPortPreemptiveTick_0:
        DC32        0xe0004000
        DC32        0xfffff030
        CFI EndBlock cfiBlock7

Have you checked if interval tick is regular and corrected? Can you 
give me Timer0 settings??? Thank you in advance!
Enrico