Toshiba TLCS-900/L1 Series Manual page 219

(2) Alarm generator
The alarm function generates 8 kinds of alarm waveform having a modulation
frequency 4096 Hz determined by the low-speed clock (32.768 kHz). And this
waveform is reversible by setting a value to a register.
By connecting a loud speaker outside, alarm tone can sound easily.
5 kinds of fixed cycle (1 Hz, 2 Hz, 64 Hz, 512 Hz and 8192 Hz) interrupts are
generated by the free-run counter, which is used for alarm generator.
(Operation)
At first, MELALMC<MELALM> have to be set as 0 in orders to select alarm
waveform as output
MELALMC<FC1:0> register, and clear internal counter. Finally alarm pattern has to
be set on 8-bit register of ALM. If it is inverted output-data, set <ALMINV> as invert.
Followings are example program, setting value of alarm pattern and waveform of
each setting value.
(Setting value of alarm pattern)
Setting Value for
ALM Register
00H
01H
02H
04H
08H
10H
20H
40H
80H
Other
(Example program)
In case of outputting AL2 pattern (31.25 ms/8 times/1 s)
LD (MELALMC), C0H
LD (ALM), 02H
waveform from MLDALM.
Alarm Waveform
0 fixed
AL1 pattern
AL2 pattern
AL3 pattern
AL4 pattern
AL5 pattern
AL6pattern
AL7 pattern
AL8 pattern
Undefined
(do not set)
; set output alarm waveform
; free-run counter start
; set AL2 pattern, start
91C824-217
TMP91C824
Then 10 be set on
2008-02-20