GL641USB
4. General Purpose I/O Ports
The GL641USB interface with peripherals is conducted via up to 8 GPIO signals. Host driver can control all of these
I/O pins directly. The GL641USB provides 3 vendor specific control transfer functions to host driver. One of these
functions is used to set I/O pins direction. One is used to read data from I/O pins. And the other one is used to write
data to I/O pins.
GPIO1 is used as a power on strapping to distinguish the application is used for Compact Flash card or other
ATA/ATAPI device. If this pin is pulled up when USB bus reset, GL641USB will treat the connected device is a
Compact Flash card. Otherwise, GL641USB will assume the connected device is an ATA/ATAPI device.
GPIO2 is used as power control signal for bus powered device, especially for Compact Flash card reader. Hence USB
bus powered device must consume less than 500uA when suspend mode, power of the Compact Flash card should be
turned off when system suspend.
GPIO3 is connected to external reset pin of ATA/ATAPI/Compact Flash card. The GL641USB can only work at True
IDE mode when Compact Flash card is connected.
GPIO4~GPIO7 are used as serial EEPROM interface. System maker can write their own vendor ID and product ID
into the serial EEPROM by a test program provided by Genesys Logic.
GPIO8 is used for Compact Flash card reader. This pin is pulled up by a resistor on board and connected to ground
when Compact Flash card is inserted. This is used as a card detection signal.
Revision 1.2
-5-
June 1, 2001
ETC [ ETC ]
