Theory of Operation: VOCON Board

2-33

 

 

INTERNAL MIC

Bias (R531,

R533, C519, C521) and Input

(R540, C522)

EXTERNAL MIC

Bias (R563,

R565, C547, C548) and Input

(R566, C549)

TP214

R555

EEPOT U509

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0 - 50K, 256 taps

 

 

 

 

 

 

 

 

MIC_OUT

 

 

 

 

 

MICIN

MIC PREAMP

 

GCAP II IC U501

 

 

_NEG

A3

 

 

 

 

 

 

 

 

 

 

Gain =

 

 

 

 

 

 

 

-14dB to 16dB

 

 

 

 

 

 

 

 

 

PGA

 

CODEC A/D

HP FILTER

 

 

MUX

-7 to +8dB

 

 

in 1dB steps

13-bit

 

cutoff = 200HZ

 

 

 

 

 

 

 

Set at 6dB

 

 

 

AUX_MIC

MIC PREAMP

 

 

 

 

 

 

_NEG

A5

 

 

 

 

 

 

 

Gain =

 

 

 

 

 

LP FILTER

 

-14dB to 16dB

 

 

 

 

 

 

 

 

 

 

 

cutoff = 3.5KHZ

 

 

 

 

 

 

 

 

 

AUX_OUT

 

 

 

 

 

R561

EEPOT U509

GCAP_CE, SCKB

CODEC_TX

CODEC_FSYNC

 

 

 

 

 

 

0 - 50K, 256 taps

SPI_MISOB

4

 

 

 

 

 

SPI_MOSIB

 

 

CODEC_DCLK

 

 

 

 

 

 

4

Patriot GPIO

Patriot SPIB

Patriot SAP/BBP

 

Flipper

 

 

PB4, PB5,

 

 

 

 

U301

 

EEPOT_CS_EXT*

PB6, PB7

 

 

 

 

 

 

 

 

 

 

 

EEPOT_CS*

 

 

 

3

TX_SSI_FSYNC

 

EEPOT_U_D*

 

 

 

 

EEPOT_INC*

 

 

 

 

TX_SSI_CLK

 

 

 

 

 

 

TX_DATA

 

 

 

 

 

 

RF D/A

 

 

 

 

 

 

 

U203

 

 

 

 

 

 

 

(On RF Board)

 

 

 

 

 

 

 

 

 

MAEPF-27418-A

Figure 2-11. VOCON Transmit Audio Path

2.5.5.2 Receive Audio Path

Refer to Figure 2-12. The receive audio data comes from the Abacus III IC U500 through the RF interface connector P201 pin 12 (RX_DATA) to the dual-core processor SRDB pin. The DSP decodes the data and sends it out through the CODEC_RX line to the GCAP II IC RX pin. The CODEC filters and converts the digital data into an analog audio signal, which, in turn, is sent to a programmable gain amplifier. The dual-core processor programs a multiplexer to route the audio signal to the A4 amplifier, which has a fixed gain of 3.5 dB. The output of the A4 amplifier is pin

EXTOUT.

From the EXTOUT pin, the audio signal goes through the pre-amplifier U502 and then to the audio power amplifier U503, which together provide approximately 30 dB of gain. The dual-core processor selects whether the amplified audio is routed to the internal speaker or the external speaker.

6881094C12-A

November 11, 2004

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Motorola SSETM 5000 service manual Receive Audio Path, Gcap II IC U501