AT89C51RB2-3CSUL Atmel, AT89C51RB2-3CSUL Datasheet - Page 79

• Manufacturer Part Number: AT89C51RB2-3CSUL
• Description: MCU 8051 16K FLASH 3V 44-PLCC
• Manufacturer: Atmel
• Series: 89Cr

Specifications of AT89C51RB2-3CSUL

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-PLCC
• Processor Series: AT89x
• Core: 8051
• Data Bus Width: 8 bit
• Data Ram Size: 1280 B
• Interface Type: UART, SPI
• Maximum Clock Frequency: 60 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 2.7 V to 5.5 V
• Mounting Style: Through Hole
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• For Use With: AT89STK-11 - KIT STARTER FOR AT89C51RX2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -

ONCE
Chip Emulation)
4180E–8051–10/06
™
Mode (ON
The ONCE mode facilitates testing and debugging of systems using AT89C51RB2/RC2
without removing the circuit from the board. The ONCE mode is invoked by driving cer-
tain pins of the AT89C51RB2/RC2; the following sequence must be exercised:
•
•
While the AT89C51RB2/RC2 is in ONCE mode, an emulator or test CPU can be used to
drive the circuit. Table 61 shows the status of the port pins during ONCE mode.
Normal operation is restored when normal reset is applied.
Table 61. External Pin Status during ONCE Mode
Weak pull-up
Pull ALE low while the device is in reset (RST high) and PSEN is high.
Hold ALE low as RST is deactivated.
ALE
Weak pull-up
PSEN
Port 0
Float
Weak pull-up
Port 1
Weak pull-up
AT89C51RB2/RC2
Port 2
Weak pull-up
Port 3
XTAL1/2
Active
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