Datasheet

Chapter 7 Keyboard Interrupt (RS08KBIV1)
MC9RS08KA2 Series Data Sheet, Rev. 4
Freescale Semiconductor 53
7.3 Register Definition
The KBI includes three registers:
• An 8-bit pin status and control register
• An 8-bit pin enable register
• An 8-bit edge select register
Refer to the direct-page register summary in Chapter 4, “Memory,” for the absolute address assignments
for all KBI registers. This section refers to registers and control bits only by their names.
The KBI registers are summarized in Table 7-2.
7.3.1 KBI Status and Control Register (KBISC)
KBISC contains the status flag and control bits, which are used to configure the KBI.
Table 7-2. KBI Register Summary
Name
76543210
KBISC
R0000KBF0
KBIE KBMOD
W KBACK
KBIPE
R0 0
KBIPE5 KBIPE4
0
KBIPE2 KBIPE1 KBIPE0
W
KBIES
R0 0
KBEDG5 KBEDG4
0
KBEDG2 KBEDG1 KBEDG0
W
76543210
R 0 0 0 0 KBF 0
KBIE KBMOD
W KBACK
Reset:00000000
= Unimplemented
Figure 7-3. KBI Status and Control Register (KBISC)
Table 7-3. KBISC Register Field Descriptions
Field Description
3
KBF
Keyboard Interrupt Flag — KBF indicates that a keyboard interrupt is detected. Writes have no effect on KBF.
0 No keyboard interrupt detected.
1 Keyboard interrupt detected.
2
KBACK
Keyboard Acknowledge — Writing a 1 to KBACK is part of the flag-clearing mechanism. KBACK always reads
as 0.