Fukuda Denshi CardiMax FX-8322, Service Manual

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Chapter 4 Operational Description
4-9
4-3-2-7 SD CARD I/F Section
y
The block diagram regarding the SD CARD I/F is shown below.
y
A CPU-integrated SD card controller is used to transfer various commands and data. To prevent inrush
current, it incorporates a FET that does not supply power unless an SD card is inserted.
4-3-2-8 RS-232C I/F Section
y
The block diagram regarding the RS-232C I/F is shown below.
y The serial signal from the CPU board is isolated from the secondary circuit using a digital isolator and then
wired to the serial connector of the equipment. I/O and internal signals of the equipment are level-converted
by the RS-232C driver. The buffer converts the 3V signals from the CPU to 5V level signals.
4-3-2-9 Sound I/F Section
y
The block diagram regarding the sound I/F is shown below.
y
The sound source data transferred from the CSPI to the CPU are converted into analog signals in the DAC.
The converted analog signals are amplified in the Audio Amp via a 14 kHz Low-pass filter and then
transferred to the speaker.
CPU
SD Card Slot
FET
COM 1 to 2
Digital
Isolator
Buffer
RS-232C Driver
PCB-7285
CPU
Primary circuit Secondary circuit
CPU
Low-Pass Filter
Audio Amp
DAC
Speaker