Kenwood NXR-700 Service Manual page 79

■ Start-up of each Control Block
• Main MPU Block
Component elements:
· Main MPU: IC703
· Flash memory: IC702
· SDRAM: IC704 and IC707
· LAN IC: IC719
· RTC: IC701
Overview of Start-up Operation:
When MPU reset line logic switches as high, the MPU
starts reading the program from the fl ash memory and ex-
pands the program to SDRAM. Linux OS begins operation
on the SDRAM after main MPU transfers the program. Main
MPU works usage of Linux OS codes. The other higher-
level applications software to the Linux OS will also be
expanded in SDRAM. On starting up, main MPU verify the
status of the registers in LAN IC except SDRAM which is
purpose of backup data even if abnormal symptom detects
in either LAN IC or SDRAM, the start-up process is not af-
fected by this error; main MPU behaves operation as if it
works properly. To express another word, either Flash mem-
ory or SDRAM has defective, a circuit behaves as if main
MPU happens malfunction. After executing all initialization
routines, the Main MPU verifies the operational status of
each MPU then transmits/ receives the operation transfer
command set to from the Modem control MPU (IC325) and
the RF control MPU (IC34) using 115.2kbps UART commu-
nications.
• RF Control MPU Block
Component elements:
· RF control MPU: IC34
· Flash memory: IC17
· DSP: IC37
Overview of Start-up Operation:
When the RF control MPU (IC34) reset line logic switches
as high, this MPU reads the boot program from the internal
ROM of MPU and then initializes the peripheral devices. Af-
ter this boot process completes, the MPU starts working with
the programs (application programs) stored in fl ash memory
(IC17) to process the preprogrammed tasks. During the pro-
cess, the MPU transfers the program to the DSP IC (IC37).
It also verifi es the operating status of DSP at certain interval.
After a series of processes completes, the RF control
MPU verifi es the operational status and then transmits and
receives the operation transfer command set to/from Main
MPU (IC703) using 115200bps UART communications.
TROUBLE SHOOTING
• Modem Control MPU Block
Component elements:
· Modem control MPU: IC325
· Flash memory: IC314
· RX DSP: IC323
· TX Vocoder DSP: IC324
Overview of Start-up Operation
When the Modem control MPU (IC325) reset line logic
switches as high, the MPU reads the boot program from the
internal ROM of MPU and then initializes the peripheral de-
vices. After this boot-up process completes, the MPU starts
working with the programs (application programs) stored in
fl ash memory (IC314) to process the preprogrammed tasks.
During the process, the MPU transfers the program to the
RX DSP IC (IC323) and TX Vocoder DSP IC (IC324). It also
confi rms the operating status of these DSP ICs. After a se-
ries of processes completes, the Modem control MPU con-
fi rms the operational status and then transmits and receives
the operation transfer command set to/from Main MPU
(IC703) using 115200 bps UART communications.
• Possible Symptoms if the Block (mainly BGA IC)
Malfunctions
Ref. No.
IC703 Main MPU
IC17
IC314
IC323 RX DSP
IC324
NXR-700
Element of
Presumption Symptoms
Block
• Since the boot program cannot be executed
at all, the LEDs do not light or fl ash.
• The operations that should be executed by
IC703 are not processed.
• Runaway of IC703.
• Migrated to the programming mode (Write).
Flash
("PG" appears on the 17-segment LED dis-
Memory
play.)
on RF
• The operations that should be executed by
control
IC34 are not processed.
MPU block
• Runaway of IC34.
• Migrated to the programming mode (Write).
Flash
("PG" appears on the 17-segment LED dis-
Memory
play.)
on Modem
• The operations that should be executed by
control
IC325 are not processed.
block
• Runaway of IC325.
• While the boot program is executed, the
operation stops (the status LED is fl ashing).
• The operations that should be executed by
IC323 are not processed.
• Runaway of IC323.
• While the boot program is executed, the
TX operation stops (the status LED is fl ashing).
Vocoder • The operations that should be executed by
DSP IC324 are not processed.
• Runaway of IC324.
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