UPD17073 NEC, UPD17073 Datasheet - Page 118

• Manufacturer Part Number: UPD17073
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
• Manufacturer: NEC

14.7 Serial Interface Operation
14.7.1 Timing chart
14.7.2 Operation of clock counter
edge of the clock pin has been detected. When the value of the clock counter reaches “8”, it is reset to “0” at the next
rising edge of the clock pin. After the clock counter has been reset to “0”, the serial communication is placed in the
wait status.
Clock counter
118
Remarks <1> Initial status (general-purpose input port)
The timing of each operation of the serial interface is described below.
This timing is applicable to both 2-wire and 3-wire modes.
Figure 14-5 shows a timing chart.
Shift clock
The initial value of the clock counter is “0”. The value of the clock counter is incremented each time the falling
The conditions under which the clock counter is reset are as follows:
(1)
(2)
(3)
(4)
Serial data
SIOTS
At power-ON reset
When clock stop instruction is executed
When “0” is written to SIOTS flag
If shift clock rises while wait status is released and present value of clock counter is “8”
<2> Start condition satisfied by general-purpose I/O port
<3> Wait released
<4> Wait timing
<5> General-purpose input port mode set
<6> Stop condition satisfied by general-purpose I/O port
<1> <2>
<3>
0
La
Figure 14-5. Timing Chart of Serial Interface
1
D7
1
2
D6
2
3
D5
3
6
7
D1
7
INT
8
8
<4>
D0
0
PD17072,17073
<5>
D7
1
<6>