SX8654ICSTRT SEMTECH [Semtech Corporation], SX8654ICSTRT Datasheet - Page 33

• Manufacturer Part Number: SX8654ICSTRT
• Description: Haptics Enabled 4/5-Wire Resistive Touchscreen Controller with Proximity Sensing
• Manufacturer: SEMTECH [Semtech Corporation]

ADVANCED COMMUNICATIONS & SENSING
5.4
5.4.1
If PROXIRQSEL = 0, an interrupt can be triggered when the user is detected to be close, detected to be far, or
both (PROXCLOSEIRQEN, PROXFARIRQEN).
If PROXIRQSEL = 1, instead of the proximity “Far” state, an interrupt can be triggered at the end of each
proximity sensing operation indicating to the host when the proximity sensing block is running
(PROXCONVDONEIRQEN). This may be used by the host to synchronize noisy system operations or to read
PROXRAW, PROXUSEFUL, PROXAVG, PROXDIFF synchronously for monitoring purposes.
In both cases above, an interrupt can also be triggered at the end of compensation (PROXCOMPDONEEN).
5.4.2
As previously mentioned, touch and proximity operations share the same ADC and hence the chip implements
time multiplexing between these two types of operations. Also, proximity sensing doesn’t need to be performed
while pen is down (not needed as host knows already something touches the screen).
In all operating modes, if PROXSCANPERIOD = 0, no proximity operation is performed (i.e. § 4.6). The following
hence assumes PROXSCANPERIOD != 0. For simplicity we also assume that NIRQ is only used for reporting
touch operations i.e. RegIrqMsk[6:4] = 000 (PROXSTAT mapped to AUX pin, or polled via I2C).
In MAN mode, a CONVERT command (if not preceded by a SELECT command) will perform a proximity
sensing operation before the touchscreen operation, whatever the pen status. Hence please note that if the
Rev 1 – 25
PROXSTAT
Figure 41 – Proximity Sensing Host Operation (Pen Trigger Mode ; RegIrqMsk[6:4] = 110 ; PROXIRQSEL = 0)
PROXSTAT
Figure 42 – Proximity Sensing Host Operation (Pen Trigger Mode ; RegIrqMsk[6:4] = 010 ; PROXIRQSEL = 1)
PROXSCANPERIOD
CONVSTAT
PROXSCANPERIOD
CONVSTAT
NIRQ
I2C Read RegIrqSrc
NIRQ
I2C Read RegIrqSrc
Pen Detection
Proximity Sensing (Analog + Digital)
Pen Detection
Proximity Sensing (Analog + Digital)
Host Operation
General Description
Proximity Sensing vs Touch Operations
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July 2011
User in range
User in range
Resistive Touchscreen Controller with Proximity Sensing
33
User out of range
User out of range
SX8654/SX8655/SX8656
Haptics Enabled 4/5-Wire
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