UPD75518 NEC, UPD75518 Datasheet - Page 60

• Manufacturer Part Number: UPD75518
• Description: 4 BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC

60
4.3 CLOCK OUTPUT CIRCUIT
(1) Configuration of the clock output circuit
(2) Functions of the clock output circuit
Remark The clock output circuit is designed so that pulses with short widths do not appear in enabling
Fig. 4-17 shows the configuration of the clock output circuit.
The clock output circuit outputs a clock pulse signal on the P22/PCL pin for remote control or for supplying
clock pulses to a peripheral LSI device.
The procedure for outputting a clock pulse signal is as follows:
(a) Select a clock output frequency, and disable clock output.
(b) Write a 0 in the P22 output latch.
(c) Set the output mode for port 2.
(d) Enable clock output.
or disabling clock output.
From the clock
generator
f
f
f
X
X
X
/2
/2
/2
CLOM3
3
4
6
0
4
Fig. 4-17 Configuration of the Clock Output Circuit
CLOM1
Selector
CLOM0
CLOM
Internal bus
P22 output
latch
PORT2.2
Output
buffer
Port 2 input/
output mode
specification bit
Bit 2 of PMGB
PCL/P22
PD75518(A)