BU21008MUV Datasheet, PDF (13/17 Pages) Rohm – Capacitive Sensor Switch Control IC

BU21008MUV
Technical Note
【F6h : Sampling Interval and Number of Samples Used for Button Press】
Name:
TIMES
Address:
F6h
Description: Defines the sampling interval and number of samples required to recognise as a button press.
CONT_T[3:0] : Push and hold judgment time ：
Governs how long it is before the chip decides it is push and hold. Given by the following equation:
Push-Hold Time = system clockx2¹⁹xCONT_T (Example: system clock 1[MHz] time : About 520[msec]).
SAMP[3:0] : Sampling Interval ：
Given by the following equation:
Sampling interval = system clockx2¹³xSAMP (Example: system clock 1[MHz] time : About 8.2[msec]).
F6h
R/W
Initial val.
Bit7
CONT_T[3]
W
0
Bit6
CONT_T[2]
W
0
Bit5
CONT_T[1]
W
0
Bit4
CONT_T[0]
W
0
Bit3
SAMP[3]
W
0
Bit2
SAMP[2]
W
0
Bit1
SAMP[1]
W
0
Bit0
SAMP[0]
W
0
【F7h : Button OFF→ON Threshold】
Name:
TH_ON2
Address:
F7h
Description: A second threshold value for determining a button off→on judgment of sensor.
The sensor output value of 8bit (register SENS_DATA) is compared with 128+ ON2 [6:0], and if it is larger,
the button is determined active.
Bit7
F7h
-
R/W
-
Initial val.
-
Bit6
ON2[6]
W
0
Bit5
ON2[5]
W
0
Bit4
ON2[4]
W
1
Bit3
ON2[3]
W
0
Bit2
ON2[2]
W
0
Bit1
ON2[1]
W
0
Bit0
ON2[0]
W
0
【F8h / F9h : Button OFF→ON Threshold Selection】
Name:
TH_ON2_CH
Address:
F8h / F9h
Description: This register is used to relate either threshold TH_ON or TH_ON2 to particular sensor channels
for button press activity determination.
1 : TH_ON2 is applied 0 :TH_ON is applied
F8h
F9h
R/W
Initial val.
Bit7
SIN7
SIN15
W
0
Bit6
SIN6
SIN14
W
0
Bit5
SIN5
SIN13
W
0
Bit4
SIN4
SIN12
W
0
Bit3
SIN3
SIN11
W
0
Bit2
SIN2
SIN10
W
0
Bit1
SIN1
SIN9
W
0
Bit0
SIN0
SIN8
W
0
【FAh : Simultaneous Press and Idle Mode Entry】
Name:
CMD
Address:
FAh
Description:
SIMUL_SEL : Simultaneous push judgment element choice ：
In the case of simultaneous key press a decision must be made to select the dominant channel. The chip allows for two
alternative methods. Either it can be based on whichever key press was first, or the priority can be based on the highest
signal level.
1 : A level of a sensor gives priority 0 : Give priority to the channel pushed earliest
INTERMIT_EN : Intermittent and the drive are enable. ：
Whether intermittent is driven at the idol mode is selected.
1：Intermittent is driven. 0：Intermittent is not driven. Initial state：Intermittent is driven.
IDLE_T[3:0] : non-detect time-out setting ：
This sets the time the chip takes to go from normal mode to idle mode in a period key inactivity.
Duration = system clockx2¹⁹xIDLE_T (Example of system clock 1[MHz]time : About 520[msec])
Bit7
Bit6
FAh SIMUL_SEL -
R/W
W
-
Initial val.
0
-
Bit5
Bit4
Bit3
- INTERMIT_EN IDLE_T[3]
-
W
W
-
1
0
Bit2
IDLE_T[2]
W
1
Bit1
IDLE_T[1]
W
1
Bit0
IDLE_T[0]
W
1
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13/16
2009.04 - Rev.B