ATMEGA48A-MMHR Atmel, ATMEGA48A-MMHR Datasheet - Page 52

• Manufacturer Part Number: ATMEGA48A-MMHR
• Description: IC MCU AVR 4K FLASH 28QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA48A-MMHR

• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Speed: 20MHz
• Number Of I /o: 23
• Eeprom Size: 256 x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 512 x 8
• Program Memory Size: 4KB (4K x 8)
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: I²C, SPI, UART/USART
• Core Size: 8-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8271C–AVR–08/10
mode bit (WDIE) are locked to 1 and 0 respectively. To further ensure program security, altera-
tions to the Watchdog set-up must follow timed sequences. The sequence for clearing WDE and
changing time-out configuration is as follows:
1. In the same operation, write a logic one to the Watchdog change enable bit (WDCE) and
2. Within the next four clock cycles, write the WDE and Watchdog prescaler bits (WDP) as
The following code example shows one assembly and one C function for turning off the Watch-
dog Timer. The example assumes that interrupts are controlled (e.g. by disabling interrupts
globally) so that no interrupts will occur during the execution of these functions.
ATmega48A/48PA/88A/88PA/168A/168PA/328/328
WDE. A logic one must be written to WDE regardless of the previous value of the WDE
bit.
desired, but with the WDCE bit cleared. This must be done in one operation.
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