Digilent DIO2 - Manual (Page 3)

Digilab DIO2 Reference Manual Digilent, Inc.
www.digilentinc.com page 3 of 19
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Power Supplies
The DIO2 board receives system power from pins 39 and 40 of connector A. Pin 40 is connected
directly to a 5VDC LDO regulator (an LM2940), and pin 39 is connected to ground. The regulator
powers all devices on the DIO2 board, including the CPLD (all outbound data signals from the DIO2
board are 5V). The regulator requires about 400mV of dropout voltage, so a DC voltage 5.5VDC -
8VDC must be applied to pin 40 of connector A for proper board operation.
Digilab system boards route unregulated voltage directly from the power supply to pin 2 of all
expansion connectors. Since pin 2 on system boards mates with pin 40 on expansion boards, the DIO2
board receives power from the supply attached to the system board.
With no LED’s illuminated, the DIO2 board typically consumes about 200mA. With all LEDs
illuminated (including all segments of the seven-segment display), the board can consume up to
350mA.
LCD
The LCD display is a 16 character, 2 line
display from the Okaya company (Okaya part
number RC1602D). The Okaya data sheet may
be found on the Digilent website.
The display uses a KS0066 Samsung controller
that has a character-generator ROM (CGROM)
containing 208 preset 5x8 character patterns, a
character-generator RAM (CGRAM) that can
hold 8 user-defined 5x8 characters, and a display
data RAM (DDRAM) that can hold 80 character
codes. Character codes written into the DDRAM
serve as indexes into the CGROM (or CGRAM).
Writing a character code into a particular DDRAM
location will cause the associated 5x8 character
pattern to appear at the corresponding display
location. The display positions can be shifted left
or right by setting a bit in the instruction register
(IR). The write-only IR is used to direct display
operations (such as clear display, shift left or right,
set DDRAM address, etc). Available instructions
are shown in the rightmost column of the table
below, together with the IR codes. A busy flag is
available to indicate whether the display has
competed the last requested operation; prior to
initiating a new operation, the flag can be checked
to see whether the previous operation has been
completed.
16 x 2 character LCD
Pin 1
40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F
01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E
50
10
67
27
DDRAM address - display postion map
DDRAM address - display postion map
after shift-left operation
DDRAM address - display postion map
after shift-right operation