Forwarded because the tag was wrong, corrected now.

Sean

>X-Warning: mitvma.mit.edu: Host pool-141-152-153-173.norf.east.verizon.net
>            claimed to be cv-server.CRED-USA.local
>X-Mailer: Microsoft Outlook, Build 10.0.2627
>Importance: Normal
>X-OriginalArrivalTime: 13 Jan 2003 02:29:04.0799 (UTC)
>                        FILETIME=[8AA442F0:01C2BAAB]
>Date:         Sun, 12 Jan 2003 21:29:04 -0500
>Reply-To: williams.engineering@verizon.net
>Sender: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
>X-PH: V4.1@mailhub3
>From: James Williams <williams.engineering@verizon.net>
>Organization: Williams Engineering
>Subject: [PIC] PWM Refuses to change frequency once set for the first time
>To: PICLIST@MITVMA.MIT.EDU
>
>Hello,
>
>I am going crazy here now and I don't know what is going on.  When I
>setup my PWM frequency for the first time for a 20KHz frequency, it
>works fine, however when I dynamically try to change the frequency to
>5KHz, it does not change the frequency.  It continues to remain at
>20KHz.  I have even tried to hard code the prescale and PR2 registers to
>see if my variables where being changed.  Even the hard coded values
>does not change the PWM frequency once it has been set for the first
>time.
>
>Here is the code I have be trying to work out.
>;TRICKEL_PRESCALE = 0x03
>;TRICKEL_DUTY_L = B'00110000'
>;TRICKEL_DUTY_H = 0x04
>;TOSC = 40MHz
>
>;Turn off the timer and disable the PWM by clearing CCP1CON
>;Move 0x03 into T2CON for a prescale of 16
>
>             BCF                  T2CON,TMR2ON,A
>             CLRF    CCP1CON,A
>             MOVFF TRICKEL_FREQ_PERIOD,PR2
>             ;Now set up the period.
>             MOVLW            B'00000011'
>             ;ANDWF           TRICKEL_PRESCALE,W,BANKED
>             IORLW  B'11111100'
>             ANDWF            T2CON,F,A
>;Set the duty cycle
>             MOVFF TRICKEL_DUTY_H,CCPR1L
>             MOVLW            B'11001111'
>             ANDWF            CCP1CON,W,A
>             IORWF TRICKEL_DUTY_L,W,BANKED
>             MOVWF           CCP1CON,A
>;Turn on timer
>             BSF                  T2CON,TMR2ON,A
>             MOVLW            B'00001100'
>;Turn on PWM without affecting the LSB of duty cycle.
>             IORWF CCP1CON,F,A              ;Clears the MSB and set for
>PWM mode
>
>Now,  you would assume that this would change the period or frequency of
>the PWM to 5KHz, but it doesn't.
>Now, if I first setup the frequency for 5KHz for the first time, then it
>is good, but then when I try to change from 5KHz to 20KHz the same
>problem occurs.  This above code works for the first attempt and there
>affect the PIC PWM refuses to change frequency.  I am pulling my hair
>out here and I don't have much left.  There has got to be a catch
>somewhere and I am missing it.
>
>--
>http://www.piclist.com hint: PICList Posts must start with ONE topic:
>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads