18

ATSAM9753

1774D–DRMSD–11/02

D[6:0] specifies which keyboard key is requesting the service, valid only if KRQ flag = 1.

Key number ranges from 0 to 87.

RAM Address

(I/O address OCH write-only)

D[6:0] RAM address css

D[7] don't care

“i” refers to the MKi or BRi signal number that ranges from 0 to 10. For example, the

information regarding the key at ROW3, column MK5/BR5, is found at RAM address

8*5+3 = 43.

The scanning hardware cycles the ROW[2:0] signals from 0 to 7 to the output pins in 45

µs (5.7 µs per row). If the alternate function ROW3 is not used, then the switch status

and ADC value information are aliased (data from 68H to 6FH = data from 60H to 6FH,

data from 78H to 7FH = data from 70H to 77H).

Table 14. RAM Address

Address

Index

Content

00H to 57H

8 x i + ROW[2:0]

Key velocity and status

58H to 5FH

ROW[2:0]

LED data

60H to 6FH

ROW[3:0]

Switch status

70H to 7FH

ROW[3:0]

ADC value