UPD784020 Datasheet, PDF (29/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

mPD784020, 784021
Table 8-1 Port Functions
Port name
Port 0
Pin
P00-P07
Port 1
Port 2
Port 3
P10-P17
P20-P27
P30-P37
Function
• Bit-by-bit input/output setting supported
• Operable as 4-bit real-time outputs
(P00-P03, P04-P07)
• Capable of driving transistors
• Bit-by-bit input/output setting supported
• Capable of driving LEDs
• Input port
• Bit-by-bit input/output setting supported
Port 6
Port 7
P60-P63
P66, P67
P70-P77
• Output-only port
• Bit-by-bit input/output setting supported
• Bit-by-bit input/output setting supported
Pull-up specification by software
Specified as a batch for all pins placed in
input mode.
Specified as a batch for all pins placed in
input mode.
Specified for the 6 bits (P22-P27) as a batch.
Specified as a batch for all pins placed in
input mode.
Specified as a batch for all pins placed in
input mode.
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8.2 CLOCK GENERATOR
A circuit for generating the clock signal required for operation is provided. The clock generator includes a frequency
divider; low current consumption can be achieved by operating at a lower internal frequency when high-speed
operation is not necessary.
Fig. 8-2 Block Diagram of Clock Generator
X1
fXX
Oscillator
1/2
1/2
1/2
1/2
X2
fXX/2
UART/IOE
INTP0 noise eliminator
Oscillation settling timer
Remark fXX : Oscillator frequency or external clock input
fCLK: Internal operating frequency
fCLK
CPU
Peripheral circuits
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