PIC18F2221-E/ML Microchip Technology, PIC18F2221-E/ML Datasheet - Page 139

• Manufacturer Part Number: PIC18F2221-E/ML
• Description: 4KB, Flash, 512bytes-RAM, 25I/O, 8-bit Family,nanoWatt 28 QFN 6x6mm TUBE
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2221-E/ML

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 25
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 10x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

14.0
The Timer2 timer module incorporates the following
features:
• 8-bit timer and period registers (TMR2 and PR2,
• Readable and writable (both registers)
• Software programmable prescaler (1:1, 1:4 and
• Software programmable postscaler (1:1 through
• Interrupt on TMR2 to PR2 match
• Optional use as the shift clock for the MSSP
The module is controlled through the T2CON register
(Register 14-1), which enables or disables the timer
and configures the prescaler and postscaler. Timer2
can be shut off by clearing control bit, TMR2ON
(T2CON<2>), to minimize power consumption.
A simplified block diagram of the module is shown in
Figure 14-1.
REGISTER 14-1:
© 2009 Microchip Technology Inc.
respectively)
1:16)
1:16)
module
TIMER2 MODULE
bit 7
bit 6-3
bit 2
bit 1-0
bit 7
Unimplemented: Read as ‘0’
T2OUTPS<3:0>: Timer2 Output Postscale Select bits
0000 = 1:1 Postscale
0001 = 1:2 Postscale
•
•
•
1111 = 1:16 Postscale
TMR2ON: Timer2 On bit
1 = Timer2 is on
0 = Timer2 is off
T2CKPS<1:0>: Timer2 Clock Prescale Select bits
00 = Prescaler is 1
01 = Prescaler is 4
1x = Prescaler is 16
Legend:
R = Readable bit
-n = Value at POR
T2CON: TIMER2 CONTROL REGISTER
PIC18F2221/2321/4221/4321 FAMILY
U-0
—
T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0
R/W-0
R/W-0
W = Writable bit
‘1’ = Bit is set
R/W-0
14.1
In normal operation, TMR2 is incremented from 00h on
each clock (F
clock input gives direct input, divide-by-4 and divide-by-
16 prescale options. These are selected by the prescaler
control bits, T2CKPS<1:0> (T2CON<1:0>). The value of
TMR2 is compared to that of the Period register, PR2, on
each clock cycle. When the two values match, the com-
parator generates a match signal as the timer output.
This signal also resets the value of TMR2 to 00h on the
next cycle and drives the output counter/postscaler (see
Section 14.2 “Timer2 Interrupt”).
The TMR2 and PR2 registers are both directly readable
and writable. The TMR2 register is cleared on any
device Reset, while the PR2 register initializes at FFh.
Both the prescaler and postscaler counters are cleared
on the following events:
• a write to the TMR2 register
• a write to the T2CON register
• any device Reset (Power-on Reset, MCLR Reset,
TMR2 is not cleared when T2CON is written.
Watchdog Timer Reset or Brown-out Reset)
Timer2 Operation
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
R/W-0
OSC
/4). A 4-bit counter/prescaler on the
R/W-0
x = Bit is unknown
R/W-0
DS39689F-page 139
R/W-0
bit 0