BU97530KVT Datasheet, PDF (31/59 Pages) Rohm – Built-in OSC circuit

BU97530KVT
Datasheet
Key Scan Operation Function
1. Key scan timing
The key scan period is 4608T(s). To reliably determine the on/off state of the keys, the BU97530KVT scans the keys twice and
determines that a key has been pressed when the key data agrees. It outputs a key data read request (a low level on SDO)
9840T(s) after starting a key scan. If the key data does not agree and a key was pressed at that point, it scans the keys
again. Thus the BU97530KVT cannot detect a key press shorter than 9840T(s).
KS1 ^{* 1}
1
*
KS2 ^*
2
2
*
KS3 ^*
3
3
*
KS4 ^*
4
4
*
KS5 ^*
5
5
*
KS6
6
6
921⁹6²T¹⁶[S^T[]^S]
T=
1
fosc
Figure 17. Key Scan Timing^(Note21)
(Note21) In sleep mode the high/low state of these pins is determined by the BU0 to BU2 bits in the control data. Key scan output signals are not output from pins
that are set “L”.
2. In Normal Mode
The pins KS1 to KS6 are set “H”.
When a key is pressed a key scan is started and the keys are scanned until all keys are released. Multiple key presses are
recognized by determining whether multiple key data bits are set.
If a key is pressed for longer than 9840T(s) (Where T=1/fosc ) the BU97530KVT outputs a key data read request (a low level on
SDO) to the controller. The controller acknowledges this request and reads the key data. However, if SCE is high during a serial
data transfer, SDO will be set “H”.
After the controller reads the key data, the key data read request is cleared (SDO is set high) and the BU97530KVT performs
another key scan. Also note that SDO, being an open-drain output, requires a pull-up resistor (between 1 KΩ and 10KΩ)
Key Input 1
Key Input 2
Key scan
9840T[S]
9840T[S]
9840T[S]
SCE
Serial data transfer Serial data transfer _{Key address(43H)}
SD_DI_I
Serial data transfer
Key address
Key address
SDO
D0
Key data read
Key data read request
Key data read
Key data read request
Figure 18. Key Scan Operation in Normal Mode
Key data read
Key data read request
1
T= _fosc
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