Details

This property should contain a comma-separated list of I/O lines numbers, for example: "24, 26, 27". Line numbers correspond to those of the pl_io_num enum. This enum is platform-specific. The declarations for the pl_io_num can be found in the "Platform-dependent Constants" section of your platform documentation.

The kp.returnlinesmapping string should only contain a list of decimal numbers. That is, use "24" and not "24- PL_IO_NUM_24". Only numerical characters are processed anyway -- writing "24- PL_IO_NUM_24,25-PL_IO_NUM_25" will set this property to "24,25". You can, of course, write str(PL_IO_NUM_24)+","+str(PL_IO_NUM_25) as well.

The order in which you list the return lines does matter -- this is the order in which the lines will be numbered. All keys connected to the first return line will have their return field (bits 4-0) of the key code set to 0. For keys connected to the second line this field will contain 1, third line -- 2, and so on.

On platforms with output buffer control, all intended return lines should be configured as inputs by your application (see io.num, io.enabled).

This property can only be changed when the keypad is disabled (kp.enabled= 0- NO). Setting the property to "" means that the keypad will have no return lines. A keypad must have at least one return line to be able to work.

Return lines of the keypad should be separate from the scan lines (see kp.scanlinesmapping). The keypad will not work properly if you designate any I/O line as both a scan and return line.