W741L250 Datasheet, PDF (11/86 Pages) Winbond – 4-BIT MICROCONTROLLER

W741L250
If the Timer 1 clock input is FT, then:
Desired Timer 1 interval = (preset value +1) / FT
Desired frequency for MFP output pin = FT ÷ (preset value + 1) ÷ 2 (Hz)
Preset value: Decimal number of Timer 1 preset value, and
FOSC: Clock oscillation frequency
1. MR1.3 = 1
2. MOV TM1, #I
MOV TM1, #I
MOV TM1H, R
4
MOV TM1L, R
8
Underflow
signal
4
External clock
via RC.0
Fosc/64
Fosc
MR1.0
MR1.1
FT
Auto-reload buffer
Enable
8 bits
8-bit Binary
Down Counter
(Timer 1)
Disable
Reset
Set MR1.3 to 1
MOV TM1, #I
1. MR1.3 = 0
2
circuit
Reset
MFP signal
S
Q
R
EVF.7
1. Reset
2. INT 7 accept
3. CLR EVF, #80H
4. Set MR1.3 to 1
5. MOV TM1, #I
MR1.2
MFP
output pin
Figure 6. Organization of Timer 1
For example, when FT equals 32768 Hz, depending on the preset value of TM1, the MFP pin will
output a single tone signal in the tone frequency range from 64 Hz to 16384 Hz. The relation between
the tone frequency and the preset value of TM1 is shown in the table below.
C
C#
TD
D#
OE
F
N F#
G
E G#
A
A#
B
Tone
frequency
130.81
138.59
146.83
155.56
164.81
174.61
185.00
196.00
207.65
220.00
233.08
246.94
3
TM1 preset value &
MFP frequency
7CH
131.07
75H
138.84
6FH
146.28
68H
156.03
62H
165.49
5DH
174.30
58H
184.09
53H
195.04
4EH
207.39
49H
221.40
45H
234.05
41H
248.24
Tone
frequency
261.63
277.18
293.66
311.13
329.63
349.23
369.99
392.00
415.30
440.00
466.16
493.88
4
TM1 preset value &
MFP frequency
3EH
260.06
3AH
277.69
37H
292.57
34H
309.13
31H
327.68
2EH
372.36
2BH
390.09
29H
420.10
26H
443.81
24H
442.81
22H
468.11
20H
496.48
Tone
frequency
523.25
554.37
587.33
622.25
659.26
698.46
739.99
783.99
830.61
880.00
932.23
987.77
5
TM1 preset value &
MFP frequency
1EH
528.51
1CH
564.96
1BH
585.14
19H
630.15
18H
655.36
16H
712.34
15H
744.72
14H
780.19
13H
819.20
12H
862.84
11H
910.22
10H
963.76
Note: Central tone is A4 (440 Hz).
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Publication Release Date: March 1998
Revision A2