Digital & Audio Section - Motorola MTP700 Detailed Service Manual

TRANSCEIVER 400 MHz
Digital & Audio Section
The digital section (see Figure 4.1-5) contains the radio's RedCap2 RISC processor, DSP
(embedded within), external memories and GCAP3. The DSP has its own processing
memory. GCAP3 contains switching and linear regulators, audio preamplifiers, 13-bit
CODEC, A/D and D/A Converters, and interfaces with an external Audio Amplifier for
receive audio.
RedCap2 controls the receive/transmit frequencies, power levels, display, keypad, acces-
sories, MMI, and other radio functions. This microprocessor can be operated through the
RS232 interface by a personal computer to program the Flash memory with firmware and
codeplug.
The DSP performs the functions of audio filtering, ACELP speech coding, Forward Error
Correction and digital modulation. The GCAP3's CODEC handles the analog-to-digital
and digital-to-analog conversions on audio signals.
The power distribution is supported by the Global Control Audio Power (GCAP3) IC. This
IC supplies power to the radio using step-down PWM regulator supplying 1.875 VDC to
the RedCap2 core, supplying V3 linear regulator 2.775VDC to the external memories,
display and RedCap2 peripheral modules, supplying V2 to GCAP3 internal logic, internal
audio amplifier and A/D converter. The regulator's power-down mode is controlled by the
RedCap2, which senses the ON or OFF condition.
INT_SPKR
EXT_SPKR
INT_EAR
Vibrator
Side Data
EXT_MIC
SIDE_SWB+
On/Off
Vol knob
MTP700 Portable Radio / Detailed Service Manual
RF Section
Audio
PA
GCAP3
24-pin
Connector
REDCAP2
REDCAP2
Figure 4.1-5 Digital Section - Block Diagram
TETRA
TXE
BBP
SPIA
REDCAP2
SIDE_OPT_SEL3
(from 24-pin connector)
SOFT_TURN_OFF
SPIB
Reset
Buffer
BOT_SWB+
CE_ON_OFF
Headset/Keyfail
INT_MIC
SIDE_OPT_SEL1
(from 24-pin connector)
SIDE_OPT_SEL2
(from 24-pin connector)
Display
40-pin
Connector
Keypad
FLASH 4M x 16 bit
SRAM 512k x 16 bit
OPT SEL
JTAG
16-pin
Connector
USB/RS232
4.1 - 9