Matrix Orbital GLK24064-25 Legacy - Manual (Page 26)

1. Resend Key Code: This mode is similar to the action of a keyboard on a PC. In this mode, when a
key is held down, the key code is transmitted immediately followed by a 1/2 second delay. After this
delay, key codes will be sent via the RS-232 interface at a rate of about 5 codes per second. This mode
has no effect if polling or if using the I 2 C interface.
2. Key Down / Key Up codes: This mode may be used when the typematic parameters of the “Resend
Key Code” mode are unacceptable or if the unit is being operated in polled mode. The host system
detects the press of a key and simulates an auto repeat inside the host system until the key release is
detected.
In this mode, when a key is held down, the key code is transmitted immediately and no other codes will be
sent until the key is released. On the release of the key, the key release code transmitted will be a value equal
to the key down code plus 20 hex. For example, the key code associated with key ’P’ (0x50) is pressed, the
release code is ’p’ (0x70).
In RS-232 polled mode or via the I 2 C interface, the “Key Down / Key Up” codes are used. However, the
user should be careful of timing details. If the poll rate is slower than the simulated auto-repeat it is possible
that polling for a key up code will be delayed long enough for an unwanted key repeat to be generated.
Figure 19: Poll Timing
5.5.2 Auto repeat mode off (254 96)
This command turns off auto repeat mode.
5.5.3 Auto transmit keypresses on (254 65)
In this mode, all keypresses are sent immediately to the host system without the use of poll keypad
command. This is the default mode on power up.
5.5.4 Auto transmit keypresses off (254 79)
In this mode, up to 10 keypresses are buffered until the unit is polled by the host system via the poll
keypad command. Issuing this command places the unit in polled mode.
Matrix Orbital GLK24064-25 22