APOLLO user manual
Issue G
114
Front panel interface
The APOLLO provides a front panel interface via connector J24. This interface provides
the following features:
•
LCD character display interface, which can be used as GPIO if the LCD character
function is not required.
•
Two user configurable LEDs which can be used as GPIO.
•
System Management bus (SMBUS) interface.
•
One user defined GPIO.
The base address of the front panel interface registers is programmed by the BIOS at
bootup. By default, it is at IO location 500h although operating systems are able to modify
this base address location. As such, we strongly recommend using the following code
fragment to determine the base address:
outportb
0x2E, 0x55
; Enter configuration mode
outportb
0x2E, 0x07
; Point to the address register
outportb
0x2F, 0x0A
: Look at the runtime register
outportb
0x2E, 0x60
; Primary base IO address high
inportb 0x2F,
ADDRHI
outportb
0x2E, 0x61
; Primary base IO address low
inportb 0x2F,
ADDRLO
outportb
0x2E, 0xAA
; Exit configuration mode
This routine determines the base address by reading the SuperIO configuration registers.
These registers are indexed and use an address register at IO location 2Eh and a data
register at 2Fh. It returns the high byte of the address in variable ADDRHI and the low
bye in ADDRLO.
Eurotech supplied Windows XP and Linux drivers determine the base address using a
routine such as this. Please contact Eurotech support for the latest driver.
LCD interface
The APOLLO board provides an LCD interface that can be used to connect to an
HD44780 or similar LCD character display. A contrast voltage and diode-protected LED
backlight power supply are also provided.
Pin 4 on connector J24 (see page
) provides the contrast voltage often required by
LCD character displays. The contrast voltage is set to 0.5V on the APOLLO board as
standard. This can be modified if required to suit the particular LCD character display
used.
The GPIO are all configured by the BIOS as open drain outputs. The IO ports are 5V
tolerant IO; with 3.3V drive level when in push-pull mode. The signalling voltage levels on
the APOLLO V2Ix and V1Ix are different due to the configuration of the SuperIO.
APOLLO V1Ix GPIO: 5V signalling using open drain outputs, 5V tolerant.
APOLLO V2Ix GPIO: 3.3V Signalling using open drain outputs, 5V tolerant.