DT_Interrupts - TMR1 Issue With 16F88

[Tabsoft]

For the 16F88 I see that you are not setting the OSCCON register which is leaving the oscillator rate at its POR default.
This coupled with your TMR0 setup and the Timer0 counter is making your LED stay on or off for over a minute.

By default the OSCCON register is set to %00000000
Which is 31.250 kHz Internal RC Oscillator Frequency (probably not what you want), and Oscillator mode defined by config bits FOSC<2:0> (which is correct)

You have the OPTION_REG register set to the following:
OPTION_REG = OPTION_REG & $80 | 1 which does this.
OPTION_REG = $FF (default) & $80 | 1 = $81 which does this.
PORTB pull-ups = disabled
Interrupt Edge = on falling edge of RB0/INT pin
TMR0 clock = Internal instruction cycle clock
Prescaler = set to TMR0
Prescaler = 1:4

Now you have Timer0 setup the following way by not setting the OSCCON and OPTION_REG registers set the way you do.

Internal instruction cycle = 1/[Processor Frequency /4] = 1/(31250/4) = 128us
Timer0 = 8bit timer
Timer0 Prescaler = 4
Timer0 Overflow Interrupt = Internal instruction cycle x Prescaler x 2^8 = 128us x 4 x 256 = 131ms
So your Timer0 Interrupt fires every 131ms.

Time to toggle LED2: T0Count x Timer0 Overflow Interrupt = 512 x 131ms = 67.11 seconds.
So your LED will toggle ~67 on/off.


For the 16F628 by default the internal oscillator runs at 4Mhz so the Internal instruction cycle is this.
Internal instruction cycle = 1/[Processor Frequency /4] = 1/(4000000/4) = 1us
Timer1 = 16bit timer
Timer1 prescaler = 8

Timer1 Overflow Interrupt = Internal instruction cycle x Prescaler x 2^16 = 1us x 8 x 65536 = .524 seconds
So your LED will toggle ~.524 seconds on/off, which is what you would expect.

To correct your issues you should set the OSCCON and OPTION_REG registers to setup a Timer0 interrupt that you would expect and adjust the Timer0 counter in the interrupt handler appropriately to adjust the on/off rate you are looking for.