• The return value is non-zero unsigned 1-byte wide containing the value:
• 0x00 None
• 0x01-0x10 Button#1…button#16 pressed briefly
• 0x11-0x20 Button#1…button#16 pressed for a long time
• 0x21-0x30 Button#1…button#16 pressed twice briefly
• 0x31-0x40 Button#1…button#16 pressed briefly three times
• 0x41…0xBF Reserved
• 0xC0…0xFA User interval
• 0xFB Error
• 0xFC…0xFF Unused
• FRC 1-byte: FRC return value is the return value +4.