C8051F502-IMR Silicon Laboratories Inc, C8051F502-IMR Datasheet - Page 275

• Manufacturer Part Number: C8051F502-IMR
• Description: MCU 8-Bit C8051F50x 8051 CISC 64KB Flash 2.5V/3.3V/5V 32-Pin QFN EP T/R
• Manufacturer: Silicon Laboratories Inc

Specifications of C8051F502-IMR

• Package: 32QFN EP
• Device Core: 8051
• Family Name: C8051F50x
• Maximum Speed: 50 MHz
• Ram Size: 4.25 KB
• Program Memory Size: 64 KB
• Operating Supply Voltage: 2.5|3.3|5 V
• Data Bus Width: 8 Bit
• Program Memory Type: Flash
• Number Of Programmable I/os: 25
• Interface Type: I2C/SPI/UART
• On-chip Adc: 32-chx12-bit
• Operating Temperature: -40 to 125 °C
• Number Of Timers: 4

26.2. Timer 2
Timer 2 is a 16-bit timer formed by two 8-bit SFRs: TMR2L (low byte) and TMR2H (high byte). Timer 2 may
operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T2SPLIT bit (TMR2CN.3) defines
the Timer 2 operation mode.
Timer 2 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 2 (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.
26.2.1. 16-bit Timer with Auto-Reload
When T2SPLIT (TMR2CN.3) is zero, Timer 2 operates as a 16-bit timer with auto-reload. Timer 2 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 2
reload registers (TMR2RLH and TMR2RLL) is loaded into the Timer 2 register as shown in Figure 26.4,
and the Timer 2 High Byte Overflow Flag (TMR2CN.7) is set. If Timer 2 interrupts are enabled (if IE.5 is
set), an interrupt will be generated on each Timer 2 overflow. Additionally, if Timer 2 interrupts are enabled
and the TF2LEN bit is set (TMR2CN.5), an interrupt will be generated each time the lower 8 bits (TMR2L)
overflow from 0xFF to 0x00.
26.2.2. 8-bit Timers with Auto-Reload
When T2SPLIT is set, Timer 2 operates as two 8-bit timers (TMR2H and TMR2L). Both 8-bit timers oper-
ate in auto-reload mode as shown in Figure 26.5. TMR2RLL holds the reload value for TMR2L; TMR2RLH
holds the reload value for TMR2H. The TR2 bit in TMR2CN handles the run control for TMR2H. TMR2L is
always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 2 Clock Select bits (T2MH and T2ML in CKCON) select either SYSCLK or
the clock defined by the Timer 2 External Clock Select bit (T2XCLK in TMR2CN), as follows:
External Clock / 8
SYSCLK / 12
SYSCLK
T2XCLK
0
1
M
H
T
3
Figure 26.4. Timer 2 16-Bit Mode Block Diagram
M
T
3
L
CKCON
T
M
H
2
M
T
2
L
0
1
M
T
1
M
T
0
S
C
A
1
S
C
A
0
TR2
TCLK
Rev. 1.2
Overflow
TL2
TMR2RLL TMR2RLH
TMR2L
To SMBus
TMR2H
Reload
C8051F50x/F51x
To ADC,
SMBus
TF2CEN
T2SPLIT
T2XCLK
TF2LEN
TF2H
TF2L
TR2
Interrupt
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