Timepiece Timer Control Register - Fujitsu MB90420/5 (A) Series Hardware Manual

MB90420/5 (A) SERIES F

18.2.1 Timepiece timer Control Register

The timepiece timer control register performs starting/stopping of the timepiece timer, control of interrupts,
and setting of the external output pins.
n Timer control register
Timepiece timer control
register higher
Address: 000059
H
Read/write
Initial value
Timepiece timer control
register lower
Address: 000058
H
Read/write
[bits 15 to 8] INT3 to INT0, INTE3 to INTE0: Interrupt flag and interrupt enable flag
INT0 to INT3 are interrupt flags. These flags are set when an overflow occurs in the second, minute, or
hour counters. When an INT bit is set when the INTE bit that corresponds to the INT bit is 1, the
timepiece timer issues an interrupt signal. These flags are designed to issue an interrupt signal in
seconds, minutes, hours, or days.
Writing 0 to the INT bit clears the INT flag (INT bit), but writing 1 to the INT bit is meaningless. When a
read-modify-write instruction is executed for the INT bit, 1 is read.
[bits 7 to 5] TST2 to TST0: Test bits
These bits are provided for device tests. In user applications, these bits must be set to 000.
[bit 2] UPDT: Rewrite bit
The UPDT bit is provided to change the value of the second/minute/hour counter.
To change the value of the counter, write the change data to the second/minute/hour register and then
set the UPDT bit to 1. The register value is loaded into the counter when the next CO signal is issued
from the 21-bit prescaler. The UPDT bit is reset by hardware when the value of the counter is rewritten.
However, when setting by software and resetting by hardware occur concurrently, the UPDT bit is not
reset.
Writing 0 to the UPDT bit is meaningless. When a read-modify-write instruction is executed for the UPDT
bit, 0 is read.
Caution: When the UPDT bit is set when the second counter indicates 59 seconds, the value of the
counter is not changed and the UPDT bit is cleared. Consequently, the value of the counter
should be changed using the ST bit.
[bit 1] OE: Output enable bit
When the OE bit is set to 1, the WOT external pin functions as an output pin for the timepiece timer. In
other cases, the WOT external pin can be used as general-purpose I/O or as other peripheral blocks.
[bit 0] ST: Start bit
When the ST bit is set to 1, the timepiece timer loads the second/minute/hour value from each register
and starts operation. When the ST bit is reset to 0, all counters and prescalers are reset to 0 and stop.
2
MC-16LX FAMILY 16-BIT MICROCONTROLLERS HARDWARE MANUAL
bit 15 bit 14 bit 13
INTE3 INT3 INTE2
(R/W) (R/W) (R/W)
(0) (0) (0)
bit 7 bit 6 bit 5
TST2 TST1 TST0
(R/W) (R/W) (R/W)
18-6
bit 12 bit 11 bit 10
INT2 INTE1 INT1
(R/W) (R/W) (R/W)
(0) (0) (0)
bit 4 bit 3 bit 2
–– –– UPDT
— — (R/W)
Bit No.
bit 9 bit 8
INTE0 INT0 WTCRH
(R/W) (R/W)
(0) (0)
Bit No.
bit 1 bit 0
0E ST WTCRL
(R/W) (R/W)