MagTek MagneSafe V5 - Manual (Page 68)

MagneSafe V5
60
Example Reset Device Response (Hex):
Result Code Data Len Data
00 00
Get Keymap Item Command (KB)
Command number: 0x03
Description: This command is used to get a key map item from the active key map.
The active key map is determined by the active key map property. Data
from a magnetic stripe card is a sequence of ASCII characters. These
ASCII characters are mapped to key strokes and these key strokes are sent
to the host to represent the ASCII character. The key map maps a single
ASCII character to a single USB key usage ID and USB key modifier
byte. The key usage ID and the key modifier byte are transmitted to the
host via USB to represent the ASCII character. The ASCII value is the
value of the ASCII character to be transmitted to the host. See an ASCII
table for the values of the ASCII character set. The USB key usage ID is a
unique value assigned to every keyboard key. For a list of all key usage
IDs see Appendix A. The key modifier byte modifies the meaning of the
key usage ID. The modifier byte indicates if any combination of the right
or left Ctrl, Shift, Alt or GUI keys are pressed at the same time as the key
usage ID. For a list and description of the key modifier byte see Appendix
B.
Starting with the firmware release with software ID 21042812F01, when
both the key usage ID and the key modifier byte are set to 0xFF for a
given ASCII value, the ALT ASCII code is sent instead of the key map
values. The ALT ASCII code is a key press combination consisting of the
decimal value of the ASCII character combined with the ALT key
modifier. For example, to transmit the ASCII character ‘?’ (063 decimal),
keypad ‘0’ is sent combined with left ALT key modifier, next keypad ‘6’
is sent combined with the left ALT key modifier, last keypad ‘3’ is sent
combined with the left ALT key modifier.
Data structure:
Request Data:
Offset Field Name Description
0 ASCII value Value of the ASCII character to be
retrieved from the key map. This can be
any value between 0 and 127 (0x7F). For
example, to retrieve the key map item for
ASCII character ‘?’ (card data end
sentinel) use the ASCII value of ‘?’ which
is 63 (0x3F).