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uU
o اأ أا UU
اا سا سا سا سا س А АИ В И ἡ И ОА
ИЕ нн М
===
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9.
SAMPLING
CIRCUIT
νο
Internal MIC
External MIC
CPU
MSM6283-02Gs
"Vin
У
τ
e
2
Line-in
MIC Amp.
Circuit
VL1
Fig. 1 Sample Sound Input Circuit
VC
Sampling Sound —
F
Input Signal
Te su fear
Sampling Start Area
E
EE
+0.315V
1
=
er
¬¬
Es
Vin (2.557V)
dU
2242N
Sampling
Start
Sampling Start Area
Fig. 2 Vin Input Trigger Level
As shown in Fig. 1, the circuit provides sampling signals to the Vin terminal of the CPU.
Resistors
100Kohm and (100 + 4.7) Kohm bias the sampling signal on 2.863V.
When the sampling sound level exceeds € 0.315V as shown in Fig. 2, the CPU starts to transmit
the sampling sound data to the RAMs during the following period.
While sampling, the CPU transmits the sampling sound data to the sampling RAMs directly.
While sampling, CPU does not output key common signals (КОО ~ KO9) so that the keyboard
becomes inoperative.
Sampled sounds are digitized in CPU and transmitted to the ВАМ.
—13—
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