1.0 INTRODUCTION
The UT69RH051 is a radiation-tolerant 8-bit microcontroller
that is pin equivalent to the MCS-51 industry standard
microcontroller when in a 40-pin DIP. The UT69RH051’s static
design allows operation from 1Hz to 20MHz. This data sheet
describes hardware and software interfaces to the UT69RH051.
2.0 SIGNAL DESCRIPTION
V
DD
:
+5V Supply voltage
V
SS
:
Circuit Ground
Port 0 (P0.0 - P0.7):
Port 0 is an 8-bit port. Port 0 pins are used
as the low-order multiplexed address and data bus during
accesses to external program and data memory. Port 0 pins use
internal pullups when emitting 1’s and are TTL compatible.
Port 1 (P1.0 - P1.7):
Port 1 is an 8-bit bidirectional I/O port with
internal pullups. The output buffers can drive TTL loads. When
the Port 1 pins have 1’s written to them, they are pulled high by
the internal pullups and can be used as inputs in this state. As
inputs, any pins that are externally pulled low sources current
because of the pullups. In addition, Port 1 pins have the alternate
uses shown in table 1.
Port 2 (P2.0 - P2.7):
Port 2 is an 8-bit port. Port 2 pins are used
as the high-order address bus during accesses to external Program
Memory and during accesses to external Data Memory that uses
16-bit addresses (i.e., MOVX@DPTR). Port 2 uses internal
pullups when emitting 1’s in this mode. During operations that
do not require a 16-bit address, Port 2 emits the contents of the
P2 Special Function Registers (SFR). The pins have internal
pullups and drives TTL loads.
Port 3 (P3.0 - P3.7):
Port 3 is an 8-bit bidirectional I/O port with
internal pullups. The output buffers can drive TTL loads. When
the Port 3 pins have 1’s written to them, they are pulled high by
the internal pullups and can be used as inputs in this state. As
inputs, any pins that are externally pulled low sources current
because of the pullups. In addition, Port 3 pins have the alternate
uses shown in table 2.
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Port
Pin
P1.0
P1.1
Table 1. Port 1 Alternate Functions
Alternate
Name
T2
T2EX
ECI
CEX0
CEX1
CEX2
CEX3
CEX4
Alternate Function
External clock input to Timer/
Counter 2
Timer/Counter 2 Capture/Reload
trigger and direction control
External count input to PCA
External I/O for PCA capture/
compare Module 0
External I/O for PCA capture/
compare Module 1
External I/O for PCA capture/
compare Module 2
External I/O for PCA capture/
compare Module 3
External I/O for PCA capture/
compare Module 4
Table 2. Port 3 Alternate Functions
Port
Pin
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
Alternate
Name
RXD
TXD
INT0
INT1
T0
T1
WR
RD
Alternate Function
Serial port input
Serial port output
External interrupt 0
External interrupt 1
External clock input for Timer 0
External clock input for Timer 1
External Data Memory write
strobe
External Data Memory read strobe
2
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