SX8661I07AULTRT Semtech, SX8661I07AULTRT Datasheet - Page 20

• Manufacturer Part Number: SX8661I07AULTRT
• Description: IC, Capacitive Button Touch And Proximity Controller, 8 SENSOR, MLPQ-28
• Manufacturer: Semtech

Specifications of SX8661I07AULTRT

• Controller Type: Capacitive Touch Screen
• Ic Interface Type: I2C
• Supply Voltage Range: 2.7V To 3.6V
• Operating Temperature Range: -40°C To +85°C

ADVANCED COMMUNICATIONS & SENSING
The AOI reports always one button. The AOI can be split over two GPIO pins (AOI-A, AOI-B). The AOI-A interface
is connected to pin GPIO7 and the AOI-B is connected to pin GPIO6. The user can map any button to either AOI-
A or AOI-B or both.
In case buttons are split to both AOI pins, multiple button touches are still resulting in one AOI reporting.
In most applications only one AOI pin will be selected. The two AOI pins allow the user a more coarse detection
circuitry at the host. Assuming a 3.3V supply and 8 buttons on one single AOI then the AOI levels could be
separated with around 0.3…0.4V. In case of using the two AOI pins, 4 buttons could be mapped on AOI-A
separated with around 0.8V (similar for 4 buttons on AOI-B) which step is about the double in case of a single
AOI.
In case of a single touch the reported button is straight forward (as in Figure 13).
If more than one button is touched the reported depends on the selected button reporting mode parameter ( 5.5).
Three reporting modes exist for the SX8661 (All, Single and Strongest).
The All reporting mode is applicable only for the I2C reporting (AOI is not available). In All-mode all buttons that
are touched are reported in the I2C buttons status bits.
In the Single-mode a single touched button will be reported on the AOI and the I2C. All touches that occur
afterwards will not be reported as long as the first touch sustains. Only when the first reported button is released
will the SX860 report another touch.
Figure 15 shows the Single-mode reporting in case of 2 touches occurring over time.
At time t1 button0 is touched and reported on the AOI. At time t2 button1 is touched as well but not reported. At
time t3 the button0 is released and button1 will be reported immediately (or after one scan period at idle level).
At time t4 both buttons are released and the AOI reports the idle level.
The button with the lowest Cap pin index will be reported in case of a simultaneous touch (that means touches
occurring within the same scan period).
Revision v3.2, January 2011
Index
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Width
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Index
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
Width
Table 8 AOI Level index vs. PWM pulse width (normal polarity)
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
Index
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
Figure 15
Width
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
Low Power, Capacitive Button Touch and Proximity Controller
Single-mode reporting with 2 touches
© 2011 Semtech Corp.
Index
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
Width
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
20
(8 sensors) with LED Drivers and Analog Output
Index
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
Width
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
Index
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
Width
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
Index
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
www.semtech.com
DATASHEET
Width
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
Index
SX8661
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
Width
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256