PD17012_15 Datasheet, PDF (117/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17012, 17P012
12.2 Basic Timer 0
12.2.1 Outline of basic timer 0
Figure 12-2 illustrates basic timer 0.
Basic timer 0 is used as a timer by detecting the status of a flip-flop that is set at fixed intervals (100, 250,
5, or 1 ms), using the BTM0CY flag (RF: address 17H, bit 0).
The contents of the flip-flop correspond to the BTM0CY flag.
If the BTM0CY flag is read first after power-on reset, 0 is always read. After that, the flag is set to 1 at fixed
intervals.
If the CE pin goes high from low, CE reset is effected in synchronization with the timing at which the BTM0CY
flag is set next.
Therefore, a power failure can be detected by reading the contents of the BTM0CY flag at system reset
(power-on reset or CE reset).
For details of power failure detection, refer to 22. RESET.
Figure 12-2. Outline of Basic Timer 0
Clock select block
BTM0CK0 flag
BTM0CK1 flag
4.5 MHz
Divider
Selector
Flip-flop
BTM0CY flag
Remarks 1. BTM0CK1 and BTM0CK0 (bits 1 and 0 of the basic timer clock select register: refer to Figure
12-3) set the time intervals at which the BTM0CY flag is set.
2. BTM0CY (bit 0 of the basic timer 0 carry FF judge register: refer to Figure 12-4) detects the
status of the flip-flop.
Data Sheet U10101EJ4V0DS
115