Matrix Orbital VK162-12 Legacy - Manual (Page 23)

4.5.1 Auto Repeat Mode On (254 126 [mode]) (R)
[mode] = 0x00 gives “Resend Key Code” mode [mode] = 0x01 gives “Key down / key up” code mode.
Two modes of auto repeat are available and are set via the same command.
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.
4.5.2 Auto Repeat Mode Off (254 96) (R)
This command turns auto repeat mode off.
Figure 20: Poll Timing
4.5.3 Auto Transmit Keypresses On (254 65) (R)
In this mode, all keypresses are sent immediately to the host system without the use of the poll keypad
command. This is the default mode on power up.
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