Chapter 18
Keyboard Interrupt Module (KBI)
18.1 Introduction
The keyboard interrupt module (KBI) provides eight independently maskable external interrupts which are
accessible via PTD0–PTD7. When a port pin is enabled for keyboard interrupt function, an internal 30kΩ
pullup device is also enabled on the pin.
18.2 Features
Features of the keyboard interrupt module include the following:
•
•
•
•
Eight keyboard interrupt pins with pullup devices
Separate keyboard interrupt enable bits and one keyboard interrupt mask
Programmable edge-only or edge- and level- interrupt sensitivity
Exit from low-lower modes
Addr.
Register Name
Keyboard Status
and Control Register Write:
Bit 7
6
5
4
3
2
1
IMASKK
0
Bit 0
MODEK
0
Read:
0
0
0
0
KEYF
0
ACKK
0
$001A
(KBSCR)
Reset:
Read:
0
KBIE7
0
0
KBIE6
0
0
KBIE5
0
0
KBIE4
0
0
KBIE3
0
Keyboard Interrupt Enable
KBIE2
0
KBIE1
0
KBIE0
0
$001B
Register Write:
(KBIER)
Reset:
= Unimplemented
Figure 18-1. KBI I/O Register Summary
18.3 I/O Pins
The eight keyboard interrupt pins are shared with standard port I/O pins. The full name of the KBI pins
are listed in Table 18-1. The generic pin name appear in the text that follows.
Table 18-1. Pin Name Conventions
KBI
Pin Selected for KBI Function by KBIEx
Bit in KBIER
Full MCU Pin Name
Generic Pin Name
KBI0–KBI7
PTD0/KBI0–PTD7/KBI7
KBIE0–KBIE7
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
277
FREESCALE [ Freescale ]
