I am new to the Pic world.

Here is what I am trying to do. I want to program a RTTY Ham transmitter using a FT18F2620 driving an AH 9834 DDS... But one big problem I had not been able to solve. The length of the timer1 interrupt. I need 22 MS . I am using D. Taylor's code to load the offset value into the timer.. The value computes out to 10541 at 1:2 prescaler... which is $292B

bcf T1CON,TMR1ON ; Turn off timer
movlw LOW(Timerset) ; 1 instruction cycle
addwf TMR1L,F ; 1 instruction cycle
movlw HIGH(Timerset) ; 1 instruction cycle
addwfc TMR1H,F ; 1 instruction cycle
bsf T1CON,TMR1ON ; 1 instruction cycle - Turn TIMER1 back on

The timer runs at its own speed. I can't seem to change the duration . The settings are shown below I have re-read the spec sheet a good many times.. I have tried settings from 0 to 65000.... It always interrupts at the same time duration...

Timerset = $292B ' 22 ms with prescale of 1:2 dec 10541
T1CON = 0 ' ZERO OUT THE TIMER REG
T1CON.5 = 0 'Prescale 00 = 1:1, 01 = 1:2
T1CON.4 = 1 ' 10 = 1:4 , 11 == 1:8
T1CON.0 = 0 'timer on = 1 timer off = 0
TMR1H = $29 'Timer1 set to 22ms
TMR1L = $2B 'Timer1 set to 22ms
RCON.7 = 1 'Enable priority levels on interrupts (IPEN)
TMR1IE VAR PIE1.0 'Enabel timer interrupt. (TMR1IE0)
TMR1IF VAR PIR1.0 'interrut flag bit (TMR1IF)
TMR1IE = 1 'enable timer
IPR1.0 = 1 'Timer1 interrupt priority high (TMR1IP)
PIE1.0 = 1 'Timer1 interrupt enable (TMR1IE)

I have a second interrupt handler for the keyboard to load an input buffer. That appears to be working well... I set it at low priority and the timer one to high priority.

I hope someone can tell me where I have gone wrong...I just can't change the time between interrupt. the timer has selected some value, and won't change... HELP!!!

Jack W0KPH

My Thanks to Joe Rocci for the hardward....