C8051F313R Silicon Labs, C8051F313R Datasheet - Page 199

• Manufacturer Part Number: C8051F313R
• Description: 8-bit Microcontrollers - MCU 8KB 10ADC
• Manufacturer: Silicon Labs

Specifications of C8051F313R

• Product Category: 8-bit Microcontrollers - MCU
• Core: 8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 25 MHz
• Program Memory Size: 8 KB
• Data Ram Size: 1.25 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 2.7 V to 3.6 V
• Package / Case: QFN-28
• Mounting Style: SMD/SMT
• A/d Bit Size: 10 bit
• A/d Channels Available: 17
• Data Rom Size: 128 B
• Interface Type: I2C, SMBus, SPI, UART
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 25
• Number Of Timers: 5
• On-chip Dac: No
• Processor Series: C8051
• Program Memory Type: Flash
• Factory Pack Quantity: 1500
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 2.7 V

17.3. Timer 3
Timer 3 is a 16-bit timer formed by two 8-bit SFRs: TMR3L (low byte) and TMR3H (high byte). Timer 3 may
operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T3SPLIT bit (TMR3CN.3) defines
the Timer 3 operation mode.
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal oscillator drives the system clock while Timer 3 (and/or the PCA) is clocked by an external preci-
sion oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
17.3.1. 16-bit Timer with Auto-Reload
When T3SPLIT (TMR3CN.3) is zero, Timer 3 operates as a 16-bit timer with auto-reload. Timer 3 can be
clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the
16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 3
reload registers (TMR3RLH and TM32RLL) is loaded into the Timer 3 register as shown in Figure 17.4,
and the Timer 3 High Byte Overflow Flag (TMR3CN.7) is set. If Timer 3 interrupts are enabled, an interrupt
will be generated on each Timer 3 overflow. Additionally, if Timer 3 interrupts are enabled and the TF3LEN
bit is set (TMR3CN.5), an interrupt will be generated each time the lower 8 bits (TMR3L) overflow from
0xFF to 0x00.
External Clock / 8
SYSCLK / 12
SYSCLK
T3XCLK
0
1
Figure 17.6. Timer 3 16-Bit Mode Block Diagram
M
H
T
3
M
T
3
L
CKCON
M
H
T
2
M
T
2
L
0
1
M
T
1
M
T
0
S
C
A
1
S
C
A
0
TR3
TCLK
Rev. 1.7
TMR3RLL TMR3RLH
TMR3L
C8051F310/1/2/3/4/5/6/7
TMR3H
Reload
To ADC
T3SPLIT
TF3LEN
T3XCLK
TF3H
TF3L
TR3
Interrupt
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