DESCRIPTION OF PIN FUNCTIONS
PIN NO.
35
NAME
nEnable
SYMBOL
nEA
DESCRIPTION
Input. When high, causes the 8051's outputs to tri-
state. When low, allows the 8051 to address external
memory. Must be low to execute code from the
embedded 8051.
Input/Output. Port 0 of the 8051. Multiplexed low
order address/data bus.
+5V power supply.
36-43
44
P0.7-0.0
Power Supply
P0.7-0.0
VCC
RESET CIRCUIT FOR THE COM20051I
The power on reset circuit for the COM20051I should be designed to provide a clean, fast transition time TTL input to
the COM20051I. Sufficient signal high time on RST (pin 10) should be provided after Vcc reaches +5V DC. The
following circuit, which provides an 8ms power-on reset pulse, is recommended:
Vcc (+5V)
22uF/
10V
220
74LS14
RST (PIN 10)
SMSC DS – COM20051I
Page 6
Rev. 03/27/2000
SMSC [ SMSC CORPORATION ]
