UPD17073 NEC, UPD17073 Datasheet - Page 82

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UPD17073

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

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Part Number:
UPD17073GB-572-1A7-A
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12. TIMER
12.1 General
system clock (75 kHz).
12.2 Basic Timer 0
12.2.1 General
the BTM0CY flag (BANK1 of RAM: address 51H, bit 0).
set to “1” at fixed time intervals.
failure can be detected.
82
Remark BTM0CY (bit 0 of basic timer 0 carry register: refer to Figure 12-2) detects the status of the flip-flop.
The timers are used to control the program execution time.
As shown in this figure, the PD17013 is provided with the following two timers:
• Basic timer 0
• Basic timer 1
The basic timer 0 is used to detect the status of a flip-flop that is set at fixed time intervals.
The basic timer 1 is used to issue an interrupt request at fixed time intervals.
The basic timer 0 can also be used to detect a power failure. The clock of each timer is generated by dividing the
Figure 12-1 outlines the basic timer 0.
The basic timer 0 is used as a timer by detecting the status of a flip-flop which is set at fixed time intervals, by using
The content of the flip-flop corresponds to the BTM0CY flag on a one-to-one basis.
The set time for BTM0CY flag (BTM0CY flag set pulse) is 125 ms (8 Hz).
If the BTM0CY flag is read for the first time after power-ON reset, its content is always “0”. After that, the flag is
If the CE pin goes high, CE reset is effected when the BTM0CY flag is set next time.
By reading the content of the BTM0CY flag at system reset (power-ON reset and CE reset), therefore, a power
For details on power failure detection, refer to 20. RESET.
75 kHz
Divider
Figure 12-1. Outline of Basic Timer 0
125 ms (8 Hz)
Basic timer
0 carry FF
Set/clear
BTM0CY flag
PD17072,17073

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