Kenwood TH-D74E Service Manual page 14

2.1.8.2 Memory Circuit
The memory circuit consists of the main processor (IC702), mobile DDR (IC701), and flash memory (IC705).
The flash memory has a capacity of 256 Mbits, including a transceiver control program and recording data for the MPU. The mobile
DDR is has a capacity of 512 Mbits. The MPU copies the program from the flash memory to mobile DDR. The MPU uses the mobile
DDR as a work area.
2.1.8.3 LCD
The main MPU (IC702) is in direct control of the LCD.
2.1.8.4 Key Detection Circuit
The I/O expansion IC (IC730) is used to detect the keys. The IC730 detects a key pressed, which will be reported to the main MPU
(IC702) through the serial line.
2.1.8.5 SUB MPU Circuit
The sub MPU (IC661) consists of an ARM-based 32-bit processor and a 64-kilobyte flash memory. The sub MPU is in control of the
IF IC and PLL IC.
2.1.8.6 DSP
The DSP circuit consists of the MPU/DSP (IC702) and a baseband signal. The DSP operates at a 139.2 MHz clock rate, the I/O section
operates at 3.3/1.8 V, and the core section operates at 1.2 V.
2.1.8.7 PC Port
The PC Port supports connections to external equipment (PCs) through the USB connector. The PC Port communicates with the main
MPU (IC702).
2.1.8.8 SD slot
The SD Port supports micro SD memory cards through the micro SD memory card connector. The SD Port communicates with the
main MPU (IC702).
2.1.8.9 Bluetooth/GPS Circuit
The Bluetooth/GPS circuit mainly consists of the Bluetooth/GPS IC (IC935).
The Bluetooth/GPS requires two clocks, one of which is the 19.2 MHz (X930) clock and the other is the slower clock at 32.768 kHz
for the UART.
The Bluetooth/GPS IC uses the HCI UART and AI2 UART to communicate with the main MPU. The level shift ICs (IC930, IC936, and
IC937) perform the level conversion of digital audio (PCM) at the UART as the interface between the main MPU (IC702) and Bluetooth/
GPS IC (IC935).
The two discrete external regulators (IC931 and IC932) provide power at 1.8 V and 3.3 V to the Bluetooth/GPS IC.
RTC
TCXO 19.2M
X700
RESET IC
IC703
40C
FLASH(256Mb)
IC705 240 x 180 LCD
mDDR(512Mb)
IC701
PC PORT
J700
MICRO SD SLOT
J701
1-14 (No.RA044<Rev.001>)
MAIN MPU
IC702
X701
/RST
/CS4
/CS2
EMIF
DDR
USB
MMCSD1
Fig.12 Control circuit
SUB MPU
FM TUNER
IC661
IC674
I2C
McASP
UART0
GPS / BT IC
IC935
McASP
UART1
UART2
CODEC IC
IC707
McASP AFB_FM
/CODEC_CS AFB_FM
SPI1 AFA
I/O EXPANDER
IC730
5 x 5 KEY MATRIX
I2C
16CH 8bit ADC
IC725
/ADC
SPI0
8CH 8bit DAC
IC671
/EVCS
SPI0
PLL IC
IC364
/PLL_A
SPI
BAND A IF IC
IC281
/IF_CS_A
BAND B IF IC
IC284
/IF_CS_B
CHARGE IC
IC585
TXRX PCB