Author Topic: PIC PWM slave problem  (Read 1613 times)

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Offline step_s

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PIC PWM slave problem
« on: April 08, 2016, 01:41:08 pm »
Hi there EEVbloggers.
I'm trying to make a synchronous buck-converter, and is controlling it from a PIC16F1574

In order to do this I need to make PWM2 run as a slave to PWM1, to make them match, but I'm having some trouble here.

Code: [Select]
    OSCCON = 0b11110000; //Setup for the internal Oscillator
    TRISA = 0b00011000; //TrisA I/O register
    TRISC = 0b00011000; //TrisC I/O register

    //PWM 1 setup   
    PWM1CLKCON = 0b00000000; //Setting clock
    PWM1PRH = 0b00000000; //Period
    PWM1PRL = 0b01000000;
    PWM1DCH = 0b00000000; //Duty Cycle
    PWM1DCL = 0b00100000;
    PWM1PHH = 0b00000000; //Phase
    PWM1PHL = 0b00000000;
    RA2PPS = 0b00000011; //Set RA2 as output
    PWM1CON = 0b10000000; //Enable PWM1
     //PWM 2 setup
    PWM2CLKCON = 0b00000000; //Setting clock   
    PWM2PRH = 0b00000000; //Period
    PWM2PRL = 0b01000000;
    PWM2DCH = 0b00000000; //Duty Cycle
    PWM2DCL = 0b00100000;
    PWM2PHH = 0b00000000; //Phase
    PWM2PHL = 0b00000000;
    PWM2OFCON = 0b00000000; //Off-set mode
    PWM2CON = 0b10100000; //Enable PWM2

    RC0PPS = 0b00000100; //Set RC0 as output

The PWM2OFCON is here mode 00 = independent, and the two PWMs work, running independently, at the same frequency.
If I then want to make the mode "One-shot slave run mode" then PWM2 has no output. . . It's constantly low.
All the other modes will result in the same problem.

Anyone who know what is going on?
Thanks in advance.

Online JPortici

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Re: PIC PWM slave problem
« Reply #1 on: April 09, 2016, 08:12:03 am »
Look at the chip's errata. Not sure if it address your problem but there is an entry named "Continuous Run Slave Offset Mode Anomaly" for the PWM module

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