C8051F314R Silicon Labs, C8051F314R Datasheet - Page 213

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C8051F314R

Manufacturer Part Number
C8051F314R
Description
8-bit Microcontrollers - MCU 8KB 10ADC
Manufacturer
Silicon Labs
Datasheet

Specifications of C8051F314R

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
LQFP-32
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
29
Number Of Timers
5
On-chip Dac
No
Processor Series
C8051
Program Memory Type
Flash
Factory Pack Quantity
500
Supply Voltage - Max
3.6 V
Supply Voltage - Min
2.7 V
Note that the 8-bit offset held in PCA0CPH4 is compared to the upper byte of the 16-bit PCA counter. This
offset value is the number of PCA0L overflows before a reset. Up to 256 PCA clocks may pass before the
first PCA0L overflow occurs, depending on the value of the PCA0L when the update is performed. The
total offset is then given (in PCA clocks) by Equation 18.4, where PCA0L is the value of the PCA0L register
at the time of the update.
The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH4 and
PCA0H. Software may force a WDT reset by writing a ‘1’ to the CCF4 flag (PCA0CN.4) while the WDT is
enabled.
18.3.2. Watchdog Timer Usage
To configure the WDT, perform the following tasks:
The PCA clock source and Idle mode select cannot be changed while the WDT is enabled. The watchdog
timer is enabled by setting the WDTE or WDLCK bits in the PCA0MD register. When WDLCK is set, the
WDT cannot be disabled until the next system reset. If WDLCK is not set, the WDT is disabled by clearing
the WDTE bit.
The WDT is enabled following any reset. The PCA0 counter clock defaults to the system clock divided by
12, PCA0L defaults to 0x00, and PCA0CPL4 defaults to 0x00. Using Equation 18.4, this results in a WDT
timeout interval of 256 system clock cycles. Table 18.3 lists some example timeout intervals for typical sys-
tem clocks.
Disable the WDT by writing a ‘0’ to the WDTE bit.
Select the desired PCA clock source (with the CPS2-CPS0 bits).
Load PCA0CPL4 with the desired WDT update offset value.
Configure the PCA Idle mode (set CIDL if the WDT should be suspended while the CPU is in Idle
mode).
Enable the WDT by setting the WDTE bit to ‘1’.
Write a value to PCA0CPH4 to reload the WDT.
Equation 18.4. Watchdog Timer Offset in PCA Clocks
Offset
=
256 PCA0CPL4
Rev. 1.7
C8051F310/1/2/3/4/5/6/7
+
256 PCA0L
213

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