PIC18F2221 MICROCHIP [Microchip Technology], PIC18F2221 Datasheet - Page 125

• Manufacturer Part Number: PIC18F2221
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

11.0
The Timer0 module incorporates the following features:
• Software selectable operation as a timer or
• Readable and writable registers
• Dedicated 8-bit, software programmable
• Selectable clock source (internal or external)
• Edge select for external clock
• Interrupt-on-overflow
REGISTER 11-1:
© 2007 Microchip Technology Inc.
counter in both 8-bit or 16-bit modes
prescaler
TIMER0 MODULE
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
T0CON: TIMER0 CONTROL REGISTER
Legend:
R = Readable bit
-n = Value at POR
bit 7
TMR0ON: Timer0 On/Off Control bit
1 = Enables Timer0
0 = Stops Timer0
T08BIT: Timer0 8-Bit/16-Bit Control bit
1 = Timer0 is configured as an 8-bit timer/counter
0 = Timer0 is configured as a 16-bit timer/counter
T0CS: Timer0 Clock Source Select bit
1 = Transition on T0CKI pin
0 = Internal instruction cycle clock (CLKO)
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
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.
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
001 = 1:4
000 = 1:2
TMR0ON
R/W-1
Prescale value
Prescale value
Prescale value
T08BIT
R/W-1
R/W-1
T0CS
W = Writable bit
Preliminary
‘1’ = Bit is set
R/W-1
T0SE
The T0CON register (Register 11-1) controls all
aspects of the module’s operation, including the
prescale selection. It is both readable and writable.
A simplified block diagram of the Timer0 module in 8-bit
mode is shown in Figure 11-1. Figure 11-2 shows a
simplified block diagram of the Timer0 module in 16-bit
mode.
PIC18F4321 FAMILY
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
R/W-1
PSA
T0PS2
R/W-1
x = Bit is unknown
T0PS1
R/W-1
DS39689E-page 123
T0PS0
R/W-1
bit 0