Chapter 3 — Theory of Operation
CV30 Fixed Mount Computer Service Manual 69
This port is routed out the second D-Sub 9-pin RS-232 connector through
another RS-232 transceiver. Mainly this port will be used to connect to the
scanner unit.
Standard UART
The main processors standard UART is connected to the Bluetooth
module. The data rate varies from 9600 to 115.2 Kbps.
SD Card Slot Interface
The SD card interface is a high-speed serial interface that sends all data
either over a single bi-directional data line or a four-bit data bus. The SD
card interface also supports the SDIO cards which uses the same signal set.
The higher order data lines have a dual function when the SDIO interface
is used.
JTAG Interface
The processor has a JTAG interface to facilitate testing and can be used to
load the bootloader into flash with a special program. These signals can be
accessed on the board by using a special fixture that plugs into the SD slot.
This is a method that the service center can use to reprogram the CV30
bootloader into flash if it becomes corrupted. Normally, the flash can be
upgraded using the bootloader software.
Signal Description Direction
BT_CTS Clear to Send Input
BT_RTS Request to Send Output
BT_RXD Received Data Input
BT_TXD Tra n sm itt ed D at a Output
Signal Description Direction
SD_CMD Command line Input
SD_CLK SD serial communcation clock Output
SD_DAT [3:0] Bi-directional data lines Input/Output
SD_CD SD slot detect Input
Signal Description
TCK Target Clock
TDI Tar ge t Da ta In put
TDO Target Data Output
TMS Target Control Signal
TRST Target Reset
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