I'm having difficulty setting up a PWM output for a LPC2214 (P0.21
pin as PWM5 single-edge output) for a 50% duty cycle continuous
pulse. I've seen a Keil LPC21xx example referencing a "PWMEMR"
register (at address 0xE001403C) used to set the state of the match
outputs. I can't find any reference to this in IAR or Philips
documentation. The curious thing is that with the following setup
code the PWM5 output will eventually begin to work (after several
minutes running from internal flash or from a debug session in
external RAM) . Is there anything that I'm missing (either in
substance or sequence) in the following setup code for "reliable"
operation?
void main(void)
{
PINSEL1 |= 0x00000400; // set P0.21 pin is set for PWM5 output
function
PWMTCR = 0x0000000A; // disable PWM counter, reset PWM Timer and
Prescale counters, enable PWM mode
PWMPR = 0x00000001; // PWM prescale counter division scaler value
( / 2 ???) ???
PWMPCR = 0x00002000; // enable PWM5 output (single-edge control)
PWMMCR = 0x00000002; // reset PWM timer on PWMMR0 count match ???
PWMMR0 = 0x00000100; // set PWM match count value (for ~= 7 KHz @
14.7456 MHz XTAL) ???
PWMMR5 = 0x00000080; // set PWM match 5 count value (1/2 PWM match
0 ???) ???
PWMLER = 0x00000021; // set PWM0 and PWM5 latch enables
PWMTCR = 0x00000009; // take PWM timer counter out of reset and
enable PWM counter
while (1); // output forever...
}
