Linx Technologies SDM-USB-QS-S - Manual (Page 6)

– – – – 6 7
The USB DPLL locks onto the NRZ data and provides separate recovered
clock and data signals to the Serial Interface Engine (SIE).
The SIE performs the parallel-to-serial and serial-to-parallel conversion,
bitstuffing / un-stuffing, and CRC calculations on the USB data.
The USB Protocol Engine manages the data from the USB control
endpoint, the USB protocol requests from the USB host controller, and the
commands for controlling the functional parameters of the UART.
Data from the USB data out endpoint is stored in the TX buffer and
removed from the buffer to the UART transmit register under control of the
UART FIFO controller.
Data from the UART receive register is stored in the RX buffer prior to being
removed by the SIE on a USB request for data from the device data in
endpoint.
The UART FIFO controller handles the transfer of data between the RX and
TX buffers and the UART transmit and receive registers.
The UART performs asynchronous 7 / 8 bit parallel-to-serial and serial-to-
parallel conversion of the data on the RS-232 interface. Control signals
supported by the UART include RTS, CTS, DSR, DTR, DCD, and RI. The
UART provides a transmitter-enable control signal (485_TX) to assist with
interfacing to RS-485 transceivers. The UART supports RTS / CTS, DSR /
DTR and X-On / X-Off handshaking options. Handshaking, where required,
is handled in hardware to ensure fast response times. The UART also
supports the RS-232 BREAK setting and detection conditions.
Installing the Drivers
The drivers for the USB module are included with the module’s
development system or may be downloaded from the Linx website at
www.linxtechnologies.com. These drivers should be downloaded onto the
hard drive of a PC or onto a disk. When the module is attached to the PC
for the first time, Windows automatically detects the device and searches
for the best driver. Windows prompts for the location of the drivers, so
browse to the folder or the disk, click Next, and Windows does the rest.
Windows XP may return an error window as shown in Figure 8.
This window is simply a warning that the driver has not gone through
Microsoft’s certification process and could potentially pose a problem for
the system. The drivers provided for the QS module are Microsoft Certified
and should not pose any problems unless modified by the user. Click the
Continue Anyway button to finish the installation process.
Figure 8: Windows XP Driver Error Window