
PIC18F1230/1330
2009 Microchip Technology Inc.
DS39758D-page 107
12.0
TIMER0 MODULE
The Timer0 module has the following features:
Software selectable as an 8-bit or
16-bit timer/counter
Readable and writable
Dedicated 8-bit software programmable prescaler
Clock source selectable to be external or internal
Interrupt on overflow from FFh to 00h in 8-bit
mode and FFFFh to 0000h in 16-bit mode
Edge select for external clock
simplified block diagram of the Timer0 module in 16-bit
mode.
writable register that controls all the aspects of Timer0,
including the prescale selection.
REGISTER 12-1:
T0CON: TIMER0 CONTROL REGISTER
R/W-1
TMR0ON
T016BIT
T0CS
T0SE
PSA
T0PS2
T0PS1
T0PS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
TMR0ON:
Timer0 On/Off Control bit
1
= Enables Timer0
0
= Stops Timer0
bit 6
T016BIT
: Timer0 16-Bit Control bit
1
= Timer0 is configured as an 8-bit timer/counter
0
= Timer0 is configured as a 16-bit timer/counter
bit 5
T0CS
: Timer0 Clock Source Select bit
1
= Transition on T0CKI pin input edge
0
= Internal clock (FOSC/4)
bit 4
T0SE
: Timer0 Source Edge Select bit
1
= Increment on high-to-low transition on T0CKI pin
0
= Increment on low-to-high transition on T0CKI pin
bit 3
PSA
: Timer0 Prescaler Assignment bit
1
= TImer0 prescaler is NOT assigned. Timer0 clock input bypasses prescaler.
0
= Timer0 prescaler is assigned. Timer0 clock input comes from prescaler output.
bit 2-0
T0PS2:T0PS0
: Timer0 Prescaler Select bits
111
= 1:256 Prescale value
110
= 1:128 Prescale value
101
= 1:64 Prescale value
100
= 1:32 Prescale value
011
= 1:16 Prescale value
010
= 1:8
Prescale value
001
= 1:4
Prescale value
000
= 1:2
Prescale value