4mhz! You don't believe in making things easy do you.
I believe it can be done on any pin, without any hardware modules, CCP or Timer, and no Interrupts.but I'm still curious to see if this can be done without the HPWM module
Last time, we used the CCP module to create the 120khz, then used XOUT to turn that output on and off. But during that 1ms period that it's sending a "1", the XOUT command is just spinning it's wheels in a PAUSEUS 1000.
Instead of just sitting there letting the hardware do all the work, why not just create the frequency in software for 1ms and be done with it.
Once again, I've never done this, but maybe I can get lucky twice in a row.
For a 120khz signal of 1ms in duration, we need to create 120 cycles.
Each cycle is 8.3333 us (1/120,000).
@ 4mhz it doesn't divide perfectly, so the closest we can get is an 8us cycle which ends up at 125khz. I hope that's close enough.
First off, in your main program, make a variable like this to use for counting the cyclesCode:LoopCounter VAR BYTE $20 SYSTEM
Now let's go back to the PBPPIC14.lib file. Un-Comment the LOWT line that we had commented previously. This gives back control of the TRIS register to the XOUT command.And, change the xout1loop that we modified before, to this ...Code:ifdef XOUT_USED LIST XOUT2 movlw 2 ; Default to 2 cycles XOUT movwf R2 ; Save number of cycles movf RR1, W ; Get data port movwf FSR ; Put it into FSR movf RM1, W ; Get data bit mask call LOWT ; Set data to low, outputThen, using it should be like normal again ...Code:xout1loop movlw 120 ; 120khz for 1ms = 120 cycles movwf LoopCounter xout120loop ; ---- 1 cycle of the 120khz --------------------- movf RM1, W ; 1 Get data bit mask iorwf INDF, F ; 2 Set the bit nop ; 3 waist some time comf RM1, W ; 4 Get inverted data bit mask andwf INDF, F ; 5 Clear the bit decfsz LoopCounter, F ; 6 Are we done yet? goto xout120loop ; 8 NO. Do it again.Once again, Fingers crossedCode:XOUT PORTB.3,PORTA.0,[house\lightsOff]
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