27963 Parallax Inc, 27963 Datasheet - Page 7

• Manufacturer Part Number: 27963
• Description: SOLUTIONS CUBED: MEMKEY
• Manufacturer: Parallax Inc

Specifications of 27963

• Accessory Type: Keypad Encoder
• Product: Microcontroller Accessories
• For Use With/related Products: BASIC Stamp®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Miniature Engineering Modules – MEMKey
Read Number of Keys (‘01’H)
command the MEMKey sends the master the number
of key presses it has in its buffer. This number will
range between 0 and 8.
Program Typematic (‘02’H)
defined as sending key press bytes for as long as a
key is pressed. It consists of two variables: delay –
the time before the repeat happens; and rate – the time
between repeats after the first repeat. After sending
this command, the master sends two more bytes: the
delay and the rate. The bytes represent the time in
2.5mS increments. A value of 1 is the shortest delay
and 255 is the largest (0 is defaulted to 255). For
example, to set the typematic rate for a 500mS delay
and a 100mS rate the following bytes would be sent to
the MEMKey: ‘02’H, ‘C8’H, ‘28’H.
Read Typematic (‘03’H) After receiving this command,
the MEMKey returns two bytes: the typematic delay
and typematic rate.
Program Debounce (‘04’H) When keys are pressed
they do not immediately make a solid electrical
connection. They “bounce” open and closed. If care
is not taken, the device reading the key could read
these bounces as separate key presses.
MEMKey has built in bounce protection. A key must be
down continuously for as long as the debounce period
before the key press is registered. After sending the
command, the master sends one byte specifying the
amount of debounce time is 2.5mS increments. 1 is
the shortest delay and 255 is the largest (0 is
defaulted to 255). For example, to set the debounce
time to 50mS the following bytes would be sent to the
MEMKey: ‘04’H, ‘14’H.
Read Debounce (‘05’H) After receiving this command,
the MEMKey returns the debounce delay byte.
Program Rows and Columns (‘06’H) The KX pins on
the MEMKey can be individually configured to be any
column or row in the matrix.
command, the master sends 9 more bytes. Each byte
indicates which position the rows and columns are to
take. The byte order is: row0, row1, row2, row3,
row4, col0, col1, col2, col3. The value in each byte
tells
SOLUTIONS CUBED
530-891-8045
the
MEMKey
Typematic key action is
After receiving this
After sending the
where
The
to
put the row or column.
represent the physical pins on the encoder
For example, to set the MEMKey’s KX pins in the
following order:: K0 = row0, K1 = row1, K2 = row2,
K3 = row3, K4 = row4, K5 = col0, K6 = col1, K7 = col2,
K8 = col3; the master would send the following bytes
to the MEMKey: ‘06’H, ‘00’H, ‘01’H, ‘02’H, ‘03’H, ‘04’H,
‘05’H, ‘06’H, ‘07’H, ‘08’H.
pin is not defined as both a column and a row; the
user must make sure this unfortunate set of
circumstances does not occur. If a value larger than 8
is received for any KX assignment, the MEMKey
receives the rest of the bytes and then ignores the
command.
Read Rows and Columns (‘07’H) After receiving this
command, the MEMKey returns the row and column
assignments to the master. It uses the same format as
the ‘Program Rows and Columns’ command.
Program User EEPROM (‘08’H) There are 64 bytes of
user accessible EEPROM, addressed ‘00’H through
‘3F’H. After sending the command byte, the master
sends the address byte and then the data byte. Any
address larger than ‘3F’H is simply wrapped back
around to the beginning of the address space. For
example, to program space ‘20’H with ‘AA’H, the
following bytes would be sent to the MEMKey: ‘08’H,
‘20’H, ‘AA’H.
Read User EEPROM (‘09’H)
command, the master must send an address byte in
the user EEPROM address space. After receiving the
address byte, the MEMKey reads the EEPROM and
then sends the value to the master.
0
1
2
3
4
5
6
7
8
There is no built in protection to ensure that one
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K0
K1
K2
K3
K4
K5
K6
K7
K8
The following values
After sending the
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