NEC PD750004, User Manual, Page: 116 / 342

96
µPD750008 USER'S MANUAL
5.2.4 Clock Output Circuit
(1) Configuration of the clock output circuit
Figure 5-20 shows the configuration of the clock output circuit.
(2) Functions of the clock output circuit
The clock output circuit outputs a clock pulse signal on the P22/PCL pin to output remote control signals
or to supply 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.
Figure 5-20. Configuration of the Clock Output Circuit
Remark The clock output circuit is designed so that pulses with short widths do not appear in enabling
or disabling clock output.
From the clock
generator
CLOM
Selector
Output
buffer
Port 2 input/
output mode
specification bit
P22 output
latch
PCL/P22
Internal bus
4
Φ
f
X
/2
3
f
X
/2
4
f
X
/2
6
PORT2.2 Bit 2 of PMGB
CLOM0 CLOM1 0 CLOM3