Triggering 5 TTL clocks simultaneously

[TurboLS]

I got it down to 6 errors, all with my IF statements. Here is what I have for a generic IF line:

IF PushButtonOnPORTABIT2 = 1 THEN GOTO vertloop ELSE GOTO buttonloop

on the following line i have

ENDIF

and doing that got rid of 3 of the errors, but now I need to figure out why it doesn't like my then goto / else goto commands.

For each of my 3 if statements, I get

bad expression
bad expression or missing then

[TurboLS]

OK, i know i have been posting a lot lately, but now i am down to 2 errors, both associated with

IF PushButtonOnPORTABIT2 = 1 then

I think it has something to do with me setting the ADCON1 register incorrectly.

[TurboLS]

OK, I fixed it (I think) to where I have no compiler errors.

basically I had to change the above line to

IF PORTA.2 = 1 then

[TurboLS]

So yeah I am still stuck with the whole reset clock thing. Is there a way I can generate a clock in hardware that is not a 50% duty cycle? By using one of the timer functions perhaps?

I was also wondering approximately how fast each of the commands in my program would take to process. Knowing that, I would be able to generate the reset clock by estimating the time in usecs.

thanks again for all the input.

[mister_e]

One thing i figure is to use the OSCLKO pin and connect to RB0 or else interrupt source. Once you'll be the in the interrupt routine, you'll be able to do everything. Generate all your delay and pin level. Will be a bit tricky to get the perfect timing but not impossible.

If you want to generate a 4MHZ clock, you'll need a 8MHZ crystal. Interrupt on rising or falling edge. Interrupt routine will generate your R, H1 and H2 frequency in one shot.

Depending your crystal speed, your instruction will be executed in few msec or less.

BUT for that kind of stuff where accuracy and precision is important, you'll probably need to do your delay and some test in assembler. Assembler instruction can be executed in 1 or 2 frequency cyle. Let's say at 8MHZ, 1 intruction every (1/(8Mhz/4)) = 0.5 uSec. Can be usefull to have a PIC who have an internal PLL to multiply your cystal speed.

If you have a 8MHZ crystal, execution time will be 4 times faster so from 0.5uSec to 0.125 uSec.

[TurboLS]

The reset, H2, and H1 will be about 3.6kHz. I don't know if there is a way I can get that with the multipliers.

Is there like a table where I can calculate the execution times? I know that "time-sensitive" commands take 1 usec with a 20Mhz clock (which is what I am using).

How long do if statements and such take, jumps to different parts of the program (like when I use the GOTO commands)?

[mister_e]

if they are constant... you can use HPWM on 2 channel... 2 different duty but the same frequency. They will run in background and they will not be interfered by anything else.

OR you can use the internal TIMER1 16bit and do you delay stuff when you get TIMER1 overflow interrupt.

at 3.6 KHZ period = 277.777 uSec

let's say you'll use a 20Mhz crystal... internal frequency 5MHZ period = 0.2 uSec = 1388.888 internal clock count. We want to change state every 1/2 period. 1388.888 uSec / 2 = 694.4444 uSec. So you'll have to preload Timer1 to 65535-694 = 64841 or $FD49.

here's a snippet to produce 3 different duty cycle with TIMER1

' program to generate Multiple duty cycle @ 5 mhz on PORTC
' Use of PIC18F2220
'
@ __CONFIG _CONFIG1H, _HS_OSC_1H 
    '  HS 

@ __CONFIG _CONFIG2L, _BORV_20_2L & _BOR_ON_2L & _PWRT_ON_2L
    '  BOR Voltage - 2.0v
    '  Brown-Out Reset enabled
    '  Power-Up Timer enabled
    
@ __CONFIG _CONFIG2H, _WDT_ON_2H
    '  Watch Dog Timer enabled

@ __CONFIG _CONFIG3H, _MCLRE_ON_3H & _PBAD_DIG_3H & _CCP2MX_ON_3H & _CCP2MX_B3_3H
    '  MCLR enabled
    '  PORTB<4:0> pins reset as digital pins
    '  CCP2 pin function on RC1
    '  CCP2 pin function on RB3 (alt defn)

@ __CONFIG _CONFIG4L, _DEBUG_OFF_4L & _LVP_OFF_4L & _STVR_ON_4L
    '  DEBUGger disabled
    '  Low Voltage Prgramming disabled
    '  Stack over/underflow Reset enabled

@ __CONFIG _CONFIG5L, _CP0_OFF_5L & _CP1_OFF_5L
    '  Block 0 readable/ may be writable 
    '  Block 1 readable/ may be writable

@ __CONFIG _CONFIG5H, _CPB_OFF_5H & _CPD_OFF_5H
    '  Boot Block readable / may be writable 
    '  Data EE memory readable / may be writable

@ __CONFIG _CONFIG6L, _WRT0_OFF_6L  & _WRT1_OFF_6L
    '  Block 0 writable
    '  Block 1 writable

@ __CONFIG _CONFIG6H, _WRTC_OFF_6H & _WRTB_OFF_6H & _WRTD_OFF_6H
    '  Config registers writable
    '  Boot block writable
    '  Data EE writable 

@ __CONFIG _CONFIG7L, _EBTR0_OFF_7L & _EBTR1_OFF_7L
    '  Block 0 readable
    '  Block 1 readable

@ __CONFIG _CONFIG7H, _EBTRB_OFF_7H
    '  Boot block readable
    
    DEFINE OSC 20 
    TRISC=0
    INTCON = %01000000 ' enable peripheral interrupt
    PIE1 = %00000001   ' enable TIMER1 overflow interrupt
	TMR1L=$49
	TMR1H=$FD
    T1CON = %00000101 ' prescaler 1:1
    				  ' Clock source = Fosc/4
    				  ' start the timer1
    on interrupt goto TMR1_Overflow
    Passes	var	bit
    clear
START: 
    goto start
    
disable
TMR1_Overflow:
    T1CON.0=0 'stop timer
    PIR1.0=0 ' reset interrupt flag
    TMR1l=$49
	TMR1H=$FD
    T1CON.0=1 'start timer
	if Passes then
    	PORTC = 6
    	pauseus 69
    	PORTC = 4
    	passes= 0
	else
       	PORTC = 1
    	passes= 1
    endif
    resume
enable

you may need to adjust the value of the TIMR1L to fine tune your frequency.

To calculate or to know the time an instruction take, you can use MPLAB's stopwatch... give a great aprox of the time.