PIC18F2431-I/SP Microchip Technology Inc., PIC18F2431-I/SP Datasheet - Page 139

• Manufacturer Part Number: PIC18F2431-I/SP
• Description: Microcontroller; 16 KB Flash; 768 RAM; 256 EEPROM; 24 I/O; 28-Pin-SPDIP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F2431-I/SP

• A/d Inputs: 5-Channel, 10-Bit
• Cpu Speed: 10 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 24
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 16K Bytes
• Ram Size: 768 Bytes
• Speed: 40 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

12.0
The Timer1 module timer/counter has the following
features:
• 16-bit timer/counter
• Readable and writable (both registers)
• Internal or external clock select
• Interrupt-on-overflow from FFFFh to 0000h
• Reset from CCP module special event trigger
• Status of system clock operation
Figure 12-1 is a simplified block diagram of the Timer1
module.
REGISTER 12-1:
 2003 Microchip Technology Inc.
(two 8-bit registers; TMR1H and TMR1L)
TIMER1 MODULE
bit 7
bit 6
bit 5-4
bit 3
bit 2
bit 1
bit 0
RD16: 16-bit Read/Write Mode Enable bit
1 = Enables register read/write of TImer1 in one 16-bit operation
0 = Enables register read/write of Timer1 in two 8-bit operations
T1RUN: Timer1 System Clock Status bit
1 = System clock is derived from Timer1 oscillator
0 = System clock is derived from another source
T1CKPS1:T1CKPS0: Timer1 Input Clock Prescale Select bits
11 =1:8 Prescale value
10 =1:4 Prescale value
01 =1:2 Prescale value
00 =1:1 Prescale value
T1OSCEN: Timer1 Oscillator Enable bit
1 = Timer1 oscillator is enabled
0 = Timer1 oscillator is shut-off
T1SYNC: Timer1 External Clock Input Synchronization Select bit
When TMR1CS = 1 (External Clock):
1 = Do not synchronize external clock input
0 = Synchronize external clock input
When TMR1CS = 0 (Internal Clock):
This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0.
TMR1CS: Timer1 Clock Source Select bit
1 = External clock from pin RC0/T1OSO/T1CKI (on the rising edge)
0 = Internal clock (F
TMR1ON: Timer1 On bit
1 = Enables Timer1
0 = Stops Timer1
Legend:
R = Readable bit
- n = Value at POR
bit 7
T1CON: TIMER1 CONTROL REGISTER
R/W-0
RD16
The oscillator inverter and feedback resistor are turned off to eliminate power drain.
T1RUN
R-0
OSC
T1CKPS1
PIC18F2331/2431/4331/4431
R/W-0
/4)
W = Writable bit
‘1’ = Bit is set
Preliminary
T1CKPS0
R/W-0
Register 12-1 details the Timer1 control register. This
register controls the Operating mode of the Timer1
module, and contains the Timer1 Oscillator Enable bit
(T1OSCEN). Timer1 can be enabled or disabled by
setting or clearing control bit TMR1ON (T1CON<0>).
The Timer1 oscillator can be used as a secondary clock
source in power-managed modes. When the T1RUN
bit is set, the Timer1 oscillator provides the system
clock. If the Fail-Safe Clock Monitor is enabled and the
Timer1 oscillator fails while providing the system clock,
polling the T1RUN bit will indicate whether the clock is
being provided by the Timer1 oscillator or another
source.
Timer1 can also be used to provide Real-Time Clock
(RTC) functionality to applications with only a minimal
addition of external components and code overhead.
T1OSCEN
R/W-0
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
T1SYNC
R/W-0
TMR1CS
x = Bit is unknown
R/W-0
DS39616B-page 137
TMR1ON
R/W-0
bit 0