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Programmer’s Reference
4-22
Copyright © ARM Limited 2000. All rights reserved.
4.4.3
Selecting register banks
The keyboard controller provides two register banks. Register bank 0 contains all of the
control and status registers, and bank 1 contains scanned matrix and alternate layout
register. If you use the standard keyboard layout, it is only bank 0 that is accessed.
Figure 4-2 shows the organization of the registers.
Figure 4-2 UR8HC007 register organization
Both register banks provide access to the page number register (at offset 255 in both
banks). This is used to select the bank to be accessed. To access bank 1 registers, you
must first write 1 to the page number register. To revert back to page 0, you must write
0 to the page number register. The default is bank 0. All other values written to this
register are ignored.
Individual registers in the bank are selected by the register offset value contained in the
message, as shown Figure 4-1 on page 4-20.
Note
For a full description of the keyboard controller registers, see the Technical Reference
Manual USAR Keyboard controller.
Page number register
Page number register
Registers Page 1
scanned matrix and
alternate layout
registers
255
00
Registers Page 0
control and status
registers
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