TS87C54X2-VCB Atmel, TS87C54X2-VCB Datasheet - Page 33

• Manufacturer Part Number: TS87C54X2-VCB
• Description: IC MCU 8BIT 16K OTP 40MHZ 44PLCC
• Manufacturer: Atmel
• Series: 87Cr

Specifications of TS87C54X2-VCB

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40/30MHz
• Connectivity: UART/USART
• Peripherals: POR, WDT
• Number Of I /o: 32
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: OTP
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

13. ONCE
4431E–8051–04/06
TM
Mode (ON Chip Emulation)
The ONCE mode facilitates testing and debugging of systems using TS80C54/58X2 without
removing the circuit from the board. The ONCE mode is invoked by driving certain pins of the
TS80C54/58X2; the following sequence must be exercised:
While the TS80C54/58X2 is in ONCE mode, an emulator or test CPU can be used to drive the
circuit
Normal operation is restored when normal reset is applied.
Table 13-1.
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
Table 13-1
External Pin Status during ONCE Mode
Weak pull-up
shows the status of the port pins during ONCE mode.
PSEN
Port 0
Float
Weak pull-up
Port 1
Weak pull-up
Port 2
AT/TS8xC54/8X2
Weak pull-up
Port 3
XTAL1/2
Active
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