TS80C51RA2-VIA Atmel, TS80C51RA2-VIA Datasheet - Page 48

• Manufacturer Part Number: TS80C51RA2-VIA
• Description: IC MCU 8BIT 256BYTE 40MHZ 40-DIP
• Manufacturer: Atmel
• Series: 80Cr

Specifications of TS80C51RA2-VIA

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40/30MHz
• Connectivity: UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Type: ROMless
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

TS80C51RA2/RD2
TS83C51RB2/RC2/RD2
TS87C51RB2/RC2/RD2
6.11. ONCE
The ONCE mode facilitates testing and debugging of systems using TS80C51Rx2 without removing the circuit
from the board. The ONCE mode is invoked by driving certain pins of the TS80C51Rx2; the following sequence
must be exercised:
While the TS80C51Rx2 is in ONCE mode, an emulator or test CPU can be used to drive the circuit Table 26.
shows the status of the port pins during ONCE mode.
Normal operation is restored when normal reset is applied.
48
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
TM
Weak pull-up
Mode (ON Chip Emulation)
PSEN
Table 25. External Pin Status during ONCE Mode
Port 0
Float
Weak pull-up
Port 1
Weak pull-up
Port 2
Weak pull-up
Port 3
Rev. C - 06 March, 2001
XTAL1/2
Active