Kontron SBC-845D-VEA, User Manual

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Display Output 3-13 SBC-845D-VEA Single Board Computer User’s Guide
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GPIO
The SBC-845D-VEA provides 4 input/output ports that can be individually configured to perform a
simple basic I/O function or a pre-defined alternated function. Users can configure each
individual port to become an input or output port by programming the register bit of the I/O
Selection. To invert the port value, the “Inversion Register” setting has to be set. Port values can
be set to read or write through the Data Register. All of these 4 ports are designed to be
functional even in power loss conditions (VCC or VSB is off). That means, these ports will always
keep their previous settings until the battery runs low.
Additionally, four extra Digital Output ports inversely amplify signals from GPIO ports. There are
open-drain buffers, which can offer greater driving capacity up to 100mA.
There are two PNP I/O port addresses that can be used to configure GPIO ports:
1) 0x2E - EFER (Extended Function Enable Register, for entering Extended Function Mode)
- EFIR (Extended Function Index Register, for identifying CR index number)
2) 0x2F - EFDR (Extended Function Data Register, for accessing desired CR)
Below are some example codes, which demonstrate the use of GPIO.
// Enter Extended Function Mode
outp(0x002E, 0x87);
outp(0x002E, 0x87);
// Assign Pin121-128 to be GPIO port 1
outp(0x002E, 0x2A);
outp(0x002F, inp(0x002F) | 0x84);
// Select Logic Device 7
outp(0x002E, 0x07);
outp(0x002F, 0x07);
// Active Logic Device 7
outp(0x002E, 0x30);
outp(0x002F, 0x01);