That's fine, there is no reason not to use it. Except that unless the work is directly related to the PWM, it might be better to do it in a Timer interrupt. For certain, no PWM calculations need to be done in an interrupt.

Richard

An Engineer's Guide to the LPC2100 Series

Thanks for the link, I will take a look.

I plan to use the ISR to do some work down the road, so I do need it.

Probably the best sample code around for the LPC2148 is at
LPC2148 Demo Code Overview http://www.jcwren.com/arm

LPC2148 Demo Code Overview http://www.jcwren.com/arm The latest demo code version is 1.44, dated 12-Jan-2009 View the latest README file Download the latest tar+gzip'ed version (Linux) Download the latest zipped version (Windows)

View on www.jcwren.com http://www.jcwren.com/arm
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Among other things, there is no need for an interrupt handler to create PWM and it usually isn't necessary to reconfigure the ADC just to start a conversion.

Read over JC's code and see if it helps.

Richard

Please ignore this. I posted here and thought it got cancelled, so I sent an email with the same problem.

I am writing some code for the LPC2148. I have some working ADC code using AD0.3 on P0.30. After adding PWM using PWM5 on P0.21 with match interrupts, the ADC always returns 0. I have been unable to determine why. Any help would be appreciated. Here is the code for each:

ADC Code:
// Select P0.30 as AD0.3
PINSEL1 |= (1 << 28);

int GetADCResult(void)
{
int result = 0;

// Perform ADC acquire and conversion
// Initialize ADC converter
AD0CR = (1<<3) // Use channel 3
| ((15-1) << 8) // 4.0MHz Clock (60.0MHz / 15)
| (1<<21) // Power up ADC
| (0<<16); // Burst Mode off

AD0CR |= (0<<26) | (0<<25) | (1<<24); // start conversion
while((AD0DR3 & (1<<31)) == 0);

// Get the result from bits 6 to 15
result = (AD0DR3>>6) & 0x3FF;

return result;
}

PWM Code:

void InitPWM(void)
{
// ----- Configure PWM interrupt (slot 8) -----

// PWM Interrupt is an IRQ interrupt so clear bit
VICIntSelect &= ~(1 << 8);
// Set PWM interrupt to slot 0 and enable slot
VICVectCntl0 = (1<<5) | 8;
// Set the address of ISR for slot 0
VICVectAddr0 = (unsigned) PWM_ISR;

// ---- PLL0 has been setup with CCLK 60Mhz and PCLK also = 60Mhz.
// === Configure P0.21 for Output as PWM5 ============= // Period: 4 ms
// Duty Cycle: 12.5%
// Pulse duration: 0.5 ms
// ----------------
PINSEL1 = (1 << 10); // Select PWM5 output for P0.21
PWMPCR = 0x0; // Select Single Edge PWM
PWMPR = PWM_PRESCALE-1; // 1 micro-second resolution
PWMMR0 = 400; // 400 ticks i.e 400*1us = 4ms period duration
PWMMR5 = 50; // 0.5 ms Initial pulse duration i.e width
PWMMCR = (1<<1) | (1<<0) // Reset PWMTC and interrupt on PWMMR0 match
| (1<<15); // interrupt on PWMMR5 match
PWMLER = (1<<0) | (1<<5); // update MR0 and MR5
PWMPCR = (1<<13); // Enable PWM output for PWM5
PWMTCR = (1<<1) ; //Reset PWM Timer and Prescale counters
// Enable
PWMTCR = (1<<0) | (1<<3); // enable counters and PWM Mode output
}
void PWM_ISR(void)
{
long regVal = PWMIR;

// Check PWM Interrupt Register to determine which match
// generated the interrupt.
if (PWMIR & (1<<0)) // PMMMR0 match - beginning of period
{
// Do X
}
else if (PWMIR & (1<<9)) // PWMMR4 match - beginning of pulse
{
// Do Y
}

PWMIR = regVal; // Clear Interrupt Register
VICVectAddr = 0x0; //End of ISR
}