AT89C5131A-PUTUM Atmel, AT89C5131A-PUTUM Datasheet - Page 68

• Manufacturer Part Number: AT89C5131A-PUTUM
• Description: IC 8051 MCU FLASH 32K USB 32QFN
• Manufacturer: Atmel
• Series: AT89C513xr

Specifications of AT89C5131A-PUTUM

• Core Processor: C52X2
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: I²C, SPI, UART/USART, USB
• Peripherals: LED, POR, PWM, WDT
• Number Of I /o: 18
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
• Core: 8051
• Processor Series: AT89x
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 48 MHz
• Data Ram Size: 1.25 KB
• Number Of Programmable I/os: 34
• Number Of Timers: 16 bit
• Operating Supply Voltage: 2.7 V to 5.5 V
• Mounting Style: SMD/SMT
• Height: 0.95 mm
• Interface Type: 2-Wire, EUART, SPI, USB
• Length: 7 mm
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Width: 7 mm
• For Use With: AT89OCD-01 - USB EMULATOR FOR AT8XC51 MCUAT89STK-10 - KIT EVAL APPL MASS STORAGEAT89STK-05 - KIT STARTER FOR AT89C5131
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Converters: -
• Lead Free Status / Rohs Status: Details

14.5
68
PCA Watchdog Timer
AT89C5130A/31A-M
Figure 14-6. PCA PWM Mode
An on-board watchdog timer is available with the PCA to improve the reliability of the system
without increasing chip count. Watchdog timers are useful for systems that are susceptible to
noise, power glitches, or electrostatic discharge. Module 4 is the only PCA module that can be
programmed as a watchdog. However, this module can still be used for other modes if the
watchdog is not needed. Figure 14-4 shows a diagram of how the watchdog works. The user
pre-loads a 16-bit value in the compare registers. Just like the other compare modes, this 16-bit
value is compared to the PCA timer value. If a match is allowed to occur, an internal reset will be
generated. This will not cause the RST pin to be driven low.
In order to hold off the reset, the user has three options:
The first two options are more reliable because the watchdog timer is never disabled as in option
#3. If the program counter ever goes astray, a match will eventually occur and cause an internal
reset. The second option is also not recommended if other PCA modules are being used.
Remember, the PCA timer is the time base for all modules; changing the time base for other
modules would not be a good idea. Thus, in most applications the first solution is the best option.
This watchdog timer won’t generate a reset out on the reset pin.
1. Periodically change the compare value so it will never match the PCA timer
2. Periodically change the PCA timer value so it will never match the compare values, or
3. Disable the watchdog by clearing the WDTE bit before a match occurs and then re-
enable it
ECOMn
CAPPn
Enable
CAPNn MATn TOGn PWMn ECCFn
Overflow
PCA Counter/Timer
8-bit Comparator
CCAPnH
CCAPnL
CL
<
≥
CCAPMn, n = 0 to 4
0xDA to 0xDE
“1”
“0”
4337K–USB–04/08
CEXn