Matrix Orbital PK202-24-USB - Manual (Page 21)

Figure 14: Poll Timing
3.3.2 Auto Repeat Mode Off (254 96)(R)
This command turns off the auto repeat mode
3.3.3 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.
3.3.4 Auto Transmit Keypresses Off (254 79)(R)
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.
3.3.5 Clear Key Buffer (254 69)
This command clears any unread keypresses. In a menuing application, if the user presses a key which
changes the menu context, any following key presses may be inaccurate and can be cleared out of the buffer
between menu changes to prevent jumping around the menu tree. It may also be used to, in effect, reset the
keypad in case the host application resets for whatever reason.
3.3.6 Poll Keypad (254 38)
The host system must be set up to receive the key codes. When the display receives this command it will
immediately return any unbuffered keypresses which may have not been read already. If there is more than
one keypress buffered the high order bit (MSB) of this returned keycode will be set (1). If this is the only
buffered keypress the MSB will be reset (0). If there are no buffered keypresses the returned code will be
0x00. Please note; in order to make use of this command, the “Auto transmit keypress” mode should be off.
Matrix Orbital PK202-24-USB 17