Kenwood NX-5300 Service Manual page 16

2.4.6.1 MPU
The MPU/DSP (IC702) is 32-bit RISC processor and fixed floating-point VLIW DSP, equipped with peripheral function.
This MPU operates at 288MHz (MAX) clock and 3.3V /1.8V/ 1.2V DC. Controls the flash memory, Mobile DDR, the receive circuit, the
transmitter circuit, the control circuit, and the display circuit and transfers data to or from an external device.
2.4.6.2 Memory Circuit
Memory circuit consists of the MPU (IC702) and the Mobile DDR (IC703), the flash memory (IC705). The flash memory has capacity
of 512M-bit that contains the transceiver control program for the MPU and stores the data. It also stores the data for transceiver chan-
nels and operating parameter that are written by the FPU. This program can be easily written from external devices. The Mobile DDR
has capacity of 512 M-bit. The MPU copies the program to the Mobile DDR from the flash memory. The MPU is used as a work area
Mobile DDR.
Flash Memory
Note:
The flash memory stores the data that is written by the FPU (KPG-D1/D1N), tuning data (Deviation, Squelch, etc.), and firmware
program (User mode, Test mode, Tuning mode, etc.). This data must be rewritten when replacing the flash memory.
Mobile DDR (static memory)
Note:
Mobile DDR is used as a work area of the MPU.
2.4.6.3 LCD
The LCD is controlled using parallel interface from the MPU (IC702).
2.4.6.4 Key Detection Circuit
Keys are detected using I/O Expander IC (IC708). If pressed key is detected by IC708, it is informed to the MPU (IC702) through serial
line.
2.4.6.5 Low Battery Warning
The battery voltage is divided using R40 and R41 and is detected by A/D converter (IC900). When the battery voltage falls below the
voltage set by the Low battery warning adjustment, the red LED blinks to notify the operator that it is time to replace the battery. If the
battery voltage falls even more (approx. 5.8V), a beep sounds and transmission stops.
Low battery warning
The red LED blinks during transmission.
The red LED blinks and the warning tone
beeps while the PTT switch is pressed.
Low battery warning
The red LED blinks during transmission.
The red LED blinks and the warning tone beeps while the PTT switch is pressed.
Battery condition
The battery voltage is low but the transceiver is still usable.
The battery voltage is low and the transceiver is not usable to make calls.
2.4.6.6 DSP
The DSP circuit consists of a MPU/DSP (IC702) and processes the baseband signal. The DSP operates at 288MHz (MAX) clock, the
I/O section operates at 3.3V/1.8V and the core section operates at 1.2V.
The DSP carries out the following processes:
• 4 Level FSK processing
• Analog FM pre-emphasis/de-emphasis
• Vocoder processing between audio codec and modulation/demodulation
• CAI processing, such as error correction encoding
• QT/DQT encoding/decoding
• DTMF encoding/decoding
• MSK encoding/decoding
• 2-tone encoding/decoding
• Compressor/expander processing
• Voice scrambler processing
• Transmit/receive audio filtering processing
• Microphone amplifier AGC processing
• Audio mute processing
• Modulation level processing
• Active Noise Reduction
• Voice recording/playback processing
• Voice announce processing
1-16 (No.RA015<Rev.002>)
Battery condition
The battery voltage is low but the transceiv-
er is still usable.
The battery voltage is low and the trans-
ceiver is not usable to make calls.