ELANsat Tech CF232-5 manual CF232 Register Interface

4. CF232 REGISTER INTERFACE

Full details of the CF232’s register interface can be found in the VPU16550 data sheet, available at Elan’s website

http://www.pccard.co.uk

For reference, the CF232 and the CF232-5 both behave as a 5V card to the host system because Vs1 and Vs2 pins are no connects. This is to make the host default to 5V when possible, giving the highest RS232 output signals and therefore best noise margins. The Card Information Structure does not define any 3.3V tuples because some platforms will also take this as a sign to run at 3.3V even when 5V is available. On a PDA or HPC, the host will power the card at 5V if it’s available, or 3.3V otherwise (despite there being no 3.3V tuple entries).

Elan Digital Systems Ltd. 6 CF232 USER’S GUIDE