digital IO on 6025E

[dcollins]

I need to use register level programming (mac platform) to access the 'extended' digital IO (i.e., the 8255 chip) lines on the 6025E. However, I can't seem to find any documentation on the address(es) to write/read to acces this. Anybody know the answer or where it is documented?

Thanks.

[dcollins]

some further clarification:

I'm using the example code and drivers from the Mac/linux package download (i.e., tSTC.h, etc.) with indivudual classes for accessing most features, including the STC's digital I/O lines. However, the examples don't seem to show accessing the 8255 DIO lines, nor do I see any obvious way to do this in the STC.h and other source code.

-Dave

[Curtis_M]

Here are the offsets for the 8255 registers from BAR1 of the 6025E:

Port A - 0x19
Port B - 0x1B
Port C - 0x1D
Config - 0x1F

If you are planning to do handshaking with this chip, you will need to know that the interrupt request lines for both port A and port B (lines PC3 and PC0) are ORed together and attached to the STC Pass_Thru_0_Interrupt using active high polarity. If you are planning to configure a single port for handshaking, you will need to ensure that the other port's corresponding interrupt line is driven low otherwise the device will interrupt until it is written low.

- Curtis

[dcollins]

Curtis,

Thanks much for that info-- it works perfectly!

I'm just doing simple I/O, no handshaking

-Dave