C8051F988-GM Silicon Laboratories Inc, C8051F988-GM Datasheet - Page 309

• Manufacturer Part Number: C8051F988-GM
• Description: IC MCU 8BIT 4KB FLASH 24QFN
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F9xxr

Specifications of C8051F988-GM

• Program Memory Type: FLASH
• Program Memory Size: 4KB (4K x 8)
• Package / Case: 24-UQFN Exposed Pad, 24-HUQFN
• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 17
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 10x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: C8051F9x
• Core: 8051
• Data Ram Size: 512 B
• Interface Type: I2C, SMBus, Enhanced UART, Enhanced SPI
• Maximum Clock Frequency: 7 KHz
• Number Of Programmable I/os: 17
• Number Of Timers: 4
• Operating Supply Voltage: 2.4 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: C8051F996DK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 10 Channel
• On-chip Dac: 10 bit, 4 Channel
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1959-5

26.4. Watchdog Timer Mode
A programmable watchdog timer (WDT) function is available through the PCA Module 2. The WDT is used
to generate a reset if the time between writes to the WDT update register (PCA0CPH2) exceed a specified
limit. The WDT can be configured and enabled/disabled as needed by software.
With the WDTE bit set in the PCA0MD register, Module 2 operates as a watchdog timer (WDT). The
Module 2 high byte is compared to the PCA counter high byte; the Module 2 low byte holds the offset to be
used when WDT updates are performed. The Watchdog Timer is enabled on reset. Writes to some
PCA registers are restricted while the Watchdog Timer is enabled. The WDT will generate a reset
shortly after code begins execution. To avoid this reset, the WDT should be explicitly disabled (and
optionally re-configured and re-enabled if it is used in the system).
26.4.1. Watchdog Timer Operation
While the WDT is enabled:






While the WDT is enabled, writes to the CR bit will not change the PCA counter state; the counter will run
until the WDT is disabled. The PCA counter run control bit (CR) will read zero if the WDT is enabled but
user software has not enabled the PCA counter. If a match occurs between PCA0CPH2 and PCA0H while
the WDT is enabled, a reset will be generated. To prevent a WDT reset, the WDT may be updated with a
write of any value to PCA0CPH2. Upon a PCA0CPH2 write, PCA0H plus the offset held in PCA0CPL2 is
loaded into PCA0CPH2 (See Figure 26.11).
PCA counter is forced on.
Writes to PCA0L and PCA0H are not allowed.
PCA clock source bits (CPS2–CPS0) are frozen.
PCA Idle control bit (CIDL) is frozen.
Module 2 is forced into software timer mode.
Writes to the Module 2 mode register (PCA0CPM2) are disabled.
PCA0CPL2
C
D
L
I
W
D
E
T
PCA0MD
W
D
C
L
K
PCA0CPH2
C
P
S
2
Figure 26.11. PCA Module 2 with Watchdog Timer Enabled
Write to
C
P
S
1
C
P
S
0
E
C
F
8-bit Adder
Enable
Adder
Enable
Rev. 1.0
PCA0CPH2
Comparator
PCA0H
8-bit
C8051F99x-C8051F98x
Match
PCA0L Overflow
Reset
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