I am programming a PIC18F67K22 and I've set it to use a 16X4Mhz Internal RC oscillator with PLL enabled.
- High level interrupt on
TIMER0
overflow - I am using MCC18 compiler.
So how to set TIMER0
to give an interrupt at every second?
I am programming a PIC18F67K22 and I've set it to use a 16X4Mhz Internal RC oscillator with PLL enabled.
TIMER0
overflow So how to set TIMER0
to give an interrupt at every second?
The TIMER0
is a 16bits timer, so to set to interrupt every 1 second you need to set:
Prescaler @ 16
TMR0 Preload @ 3036
The equation:
$$T = \left(\frac{4}{Fosc}\right) \cdot Presc \cdot (Resolution - Preload)$$
Where:
Sample code:
// Timer0 Registers:16-Bit Mode; Prescaler=1:16; TMRH Preset=$BD;
// TMRL Preset=$DC; Freq=1,00Hz; Period=1,00 s
T0CON.TMR0ON = 1; // Timer0 On/Off Control bit: 1=Enables Timer0 / 0=Stops Timer0
T0CON.T08BIT = 0; // Timer0 8-bit/16-bit Control bit: 1=8-bit timer/counter / 0=16-bit timer/counter
T0CON.T0CS = 0; // TMR0 Clock Source Select bit: 0=Internal Clock (CLKO) / 1=Transition on T0CKI pin
T0CON.T0SE = 0; // TMR0 Source Edge Select bit: 0=low/high / 1=high/low
T0CON.PSA = 0; // Prescaler Assignment bit: 0=Prescaler is assigned; 1=NOT assigned/bypassed
T0CON.T0PS2 = 0; // bits 2-0 PS2:PS0: Prescaler Select bits
T0CON.T0PS1 = 1;
T0CON.T0PS0 = 1;
TMR0H = $BD; // preset for Timer0 MSB register
TMR0L = $DC; // preset for Timer0 LSB register
T0CON.PSA = 0
instead of T0CON.PSA = 1
. They attempted to edit you answer instead of posting a comment to bring the issue to your attention, which was rejected. Their comment was the following, in case you can't access the link above: PSA must be zero for the prescaler to be considered. This code functions improperly when this bit is set to 1.
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