Eurotech PXA320, Руководство пользователя

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Hardware Specification
110120-1000A
23
Digital I/O
Ports designated as digital I/O on the ADSmartIO controller can be individually configured
as inputs or outputs. If you write a "1" (logic level high) to an I/O port when it is
configured as an input, it enables an internal pull-up resistor.
A/D Inputs
Each of the Port A I/Os (PA0-PA7) includes an analog-to-digital (A/D) converter. The
converters give full-scale readings when the input voltage is equal to voltage reference
V
REF
(e.g. V=V
REF

reading/1023).
Keypad Scan
The ADSmartIO can scan a matrix keypad up to eight by eight keys in size. Matrix
keypads are simpler, cost less than full keyboards, and can be easily customized for your
application. Also, you can create a keypad matrix from a collection of normally-open
switches.
When used to scan a keypad, the ADSmartIO configures the ROWn lines as inputs with
software pull-ups enabled and configures the COLn lines as outputs set to "1" (logic level
high). For the scan, the keypad scanner sets successive COLn outputs to "0" (logic level
low), then looks for a "0" on one of the ROWn inputs. The scanner re-reads the pressed
key after a delay to debounce the key press.
Unused column lines can be used for digital I/O or A/D inputs. Unused row lines can be
used for digital I/O only.
The following diagram illustrates how to connect a 3x3 keypad matrix. The pull-ups on
the inputs are the software-activated internal resistors of the ADSmartIO, while the series
resistors are located on the GCM.
SW1
SW4
SW7
SW2
SW5
SW8
SW3
SW6
SW9
ROW 0
ROW 1
ROW 2
COL 0
COL 1
COL 2
ADSmartIO Controller
Graphics ClientM
3 x 3 Keypad