Triggering 5 TTL clocks simultaneously

[TurboLS]

Also, I saw a blurb in the PBP manual about the fact that I can check the interrupt flag without actually enabling interrupts. If I did it that way, then I could merely do a check condition statement, similar to this, right?:

IF PORTB.2 = 1 AND INTERRUPTFLAG = 1 ' When horizontal 1 is high and reset is high

' Do the H1 > low, H2 > high, ADC conversion and the SEROUT2

[TurboLS]

OK, I checked the datasheet and the interrupt flag bit is bit 1 of the INTCON register. It also says that I have to reset it in software once an interrupt has occurred. So I was thinking if I just set the INTCON.1 = 0 right before the condition statement, then I could just wait until the INTCON.1 = 1 before clocking the horizontals. What do you think?

[Bruce]

Yep. I do this all the time.

Disable global interrupts (INTCON.7 = 0), and just monitor & reset interrupt flags as needed. Very handy.

[TurboLS]

Should I still enable the INTCON1 register? I have it set to %1001000 to use the RB0 interrupt. I have the HWPM (which is to be the interrupt source) set as follows:

HPWM 1,64,3600 ' Supposed to send HPWM 3.6KHZ at 25% duty

[TurboLS]

I tried compiling that and I get

Symbol not previously defined (INTCON1)

The updated code is as follows:

' Connect analog input to (RA0)
' Connect clocks to PORTB
' PORTB.0 is the Vphase1 clock
' PORTB.1 is the Vphase2 clock
' PORTB.2 is the Hphase1 clock
' PORTB.3 is the Hphase2 clock
' The reset will be connected to a HWPM clock pin #17
' Connect pin 2 from the DB9 connector to PORTC.6
' Have a +5V source ready to touch PORTA.2 to trigger clocking process

include "modedefs.bas"

' Define ADCIN parameters
Define ADC_BITS 8 ' Set number of bits in result
DEFINE OSC 20 ' Sets clock speed to 20Mhz
Define ADC_CLOCK 4 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS

HPWM 1,64,3600 ' Supposed to send HPWM 3.6KHZ at 25% duty

INTCON1 = %1001000 ' Enable RB0 Interrupt
INTCON.7 = 0 ' Disables global interrupts
TRISA = %11111111 ' Set PORTA to all input
ADCON1 = %00001101 ' Set PORTA analog, except for pin 2
TRISB = %00000000 ' Set PORTB to all output
Pause 500 ' Wait .5 second
Pause 500 ' Wait .5 second

horizpulse var byte
vertpulse var byte
adval var byte ' Create adval to store result

horizpulse = 1 ' Initialize counters, initial states
vertpulse = 1
PORTB.0 = 0
PORTB.1 = 0
PORTB.2 = 1
PORTB.3 = 0

buttonloop:
IF PORTA.2 = 1 then
GOTO vertloop
else
GOTO buttonloop ' Waits for 5V that signals shutter is closed
ENDIF
vertloop:
horizpulse = 1
PORTB.0 = 1
PAUSEUS 139
PORTB.0 = 0
PORTB.1 = 1
PAUSEUS 139
PORTB.0 = 1
PORTB.1 = 0
PAUSEUS 139
PORTB.0 = 0
PAUSEUS 270
vertpulse = vertpulse + 1
IF vertpulse < 512 THEN
GOTO horizloop
ELSE
GOTO buttonloop
ENDIF
horizloop:
INTCON.1 = 0 ' Resets interrupt flag to 0
Resetcheck: ' Loops back to make sure
PAUSEUS 2 ' the PORTB.2 goes low and
IF INTCON.1 = 0 THEN ' PORTB.3 goes high as close
GOTO Resetcheck ' to the external trigger's
ELSE ' rising edge as possible
ENDIF
PORTB.2 = 0
PORTB.3 = 1
PAUSEUS 139
PORTB.3 = 0
PORTB.2 = 1
PAUSEUS 15
ADCIN 0, adval ' A/D 8 bit value from PORTA.0 into adval
SEROUT2 PORTC.6,16416,[BIN8 adval,13,10] ' Output 8 bit word serially to PC from C.6
PAUSEUS 87
horizpulse = horizpulse + 1
IF horizpulse < 784 THEN
GOTO horizloop
ELSE
PAUSEUS 270
GOTO vertloop
ENDIF
END

[Bruce]

There is no INTCON1 register. That would be why you get the error. Look at your datasheet.

To monitor interrupt "flag bits" you do not need to enable any interrupt enable bits or global interrupts.

Any event or condition that will trigger the interrupt, will set the interrupts flag bit. This happens regardless of whether you have "any" interrupt enabled or disabled.

A "Flag bit" indicates that an interrupt event occurred.

The interrupt "Enable bit" allows program execution to branch to the interrupt vector address (if global interrupts are enabled) when the flag bit is set by the event that caused the interrupt.

You can setup the RB0/INT0 on the 18F4520 to set the interrupt flag bit on a low-to-high or high-to-low transition on RB0/INT0. See the datasheet under INTCON2.

Then all you need to do is monitor INTCON.1 (this means INTCON register bit #1 NOT INTCON1) which is the "flag bit" inidicating the transition (event) on RB0/INT0 has occured.

After reading this bit, then reset it (clear it to 0) so you can check it again later to see if the event has happend again.

[TurboLS]

OK, I checked the manual and bit 6 controls the external 0 flag. I set it to '1' for the rising edge.

INTCON2 = %0100000 ' External Interrupt Flag on Rising Edge

Do I have to set the PORTB pull up enable bit?

Also, RB0 will be read as an input (wired from the HWPM pin 17), so I will have to reconfigure my TRISB register to accept an input on PORTB, right?

thanks again for the help.