Getting a PCM Output on uPSD3400

[davidm]

Posted on February 03, 2006 at 00:58

Getting a PCM Output on uPSD3400

[davidm]

Posted on May 17, 2011 at 12:10

My attempts at getting a simple PWM output on TCM5 leaves me baffled.

My Keil code on a 24MHz uPSD3434E is:-

PCACON1 = 0x00; // Disable PCA, use prescaled clock

CCON3 = 0x14; // 1:16 prescaler, PCA clock enabled

TCMMODE5 = 0x41; // fixed frequency PWM

CAPCOMH5 = 0x80; // nominal 50% duty cycle

PCACH1 = PCACL1 = 0; // zero the counter

// Set P4.6 for TCM5 use

P4SFS0 |= 0x40;

P4SFS1 &= ~0x40;

PCACON1 |= 0x40; // Enable PCA

I am not seeing any activity on P4.6 so I have missed something, perhaps others can see my obvious mistake.

To add a note: I assume interrupts are not necessary when operating the PCA for PWM output as all interaction is contained within the PCA hardware.

[davidm]

Posted on May 17, 2011 at 12:10

To answer my own post - in another software module P4SFS0 was being cleared soon after the PWM setup - effectively returning the port pin to GPIO mode. No wonder there was no PWM activity.

Lesson learnt - adjust only those attributes that are applicable to the module which in my case is P4SFS0 &= ~0xC0 and not P4SFS0 = 0 as I had.