(1) Setting of music frequency (controlled by registers R0 ~ R5)
The frequencies of the square wave generated by the music generators for the
three channels (A,B and C) are controlled by registers R0 through R5. R0 and
R1 control channel A, R2 and R3 are used for channel B, and R4 and R5 control
channel C. The oscillation frequency fT is obtained in the following manner
from the value of the register TP(decimal).
fT = fMaster
-------
16TP
fMaster is the frequency of the master clock (this is the input click
frequency when
SEL is high, and 1/2 of this frequency when low).
Rough tone adjustment Fine tone adjustment
register Channel register
R1 A R0
R3 B R2
R5 C R4
B7 B6 B5 B4 B3 B2 B1 B0 B7 B6 B5 B4 B3 B2 B1 B0
\---------/| \ /
Not used | \ /
| |
TP11 TP10 TP9 TP8 TP7 TP6 TP5 TP4 TP3 TP2 TP1 TP0
12 bit oscillation frequency setting value (TP)
(2) Setting of noise generator (controlled by register R6)
The noise frequency fN is obtained from the register value NP(decimal) in the
following manner.
fN = fMaster (fMaster if the frequency of the master clock)
-------
16NP
Noise frequency register R6
B7 B6 B5 B4 B3 B2 B1 B0
\------/| \
Not used| \
| |
NP4 NP3 NP2 NP1 NP0
5 bit noise frequency setting value (NP)
(3) Settings of mixer and I/O ports (controlled by register R7)
The mixer is used to combine music and noise components. The combination is
determined by bits B5 ~ B0 of register R7. Sound is output when a '0' is
written to the register. Thus, when both the noise and tone are '0', the
output is combined by the mixer. When the noise is '0' and the tone is '1',
only the noise signal is output. When the noise is '1' and the tone is '0',
music (square wave) is output. Nothing is output when both the noise and tone
are '1'. Selection of input/output for the I/O ports is determined by bits B7
and B6 of register R7. Input is selected when '0' is written to the register
bits.
I/O port and mixer setting register R7
B7 B6 B5 B4 B3 B2 B1 B0
/ /| |\ \
/ / | | \ \
I/O Noise Tone
B A C B A C B A
(Input is selected for I/O port when '0', and noise or tone can be output
when '0')
Version: v005
22
Date: 22.05.2012
