C8051F70X_0910 Datasheet, PDF (74/290 Pages) Silicon Laboratories – Mixed Signal ISP Flash MCU Family

C8051F70x/71x
If auto-scan is enabled when the device enters suspend mode, auto-scan will remain enabled and running.
This feature allows the device to wake from suspend through CS0 greater-than comparator event on any
configured capacitive sense input included in the auto-scan sequence of inputs.
SFR Configuration:
CS0CN = 0x80 ^{Enables Capsense0}
CS0CF = 0x70
CS0SS = 0x02
CS0SE = 0x0D
Enables Auto-scan
as start-of-
conversion source
Sets P2.2 as Auto-
scan starting channel
Sets P3.5 as Auto-
scan ending channel
P2MDIN = 0xF2
P3MDIN = 0x04
Configures P2.3,
P2.2, P2.0 as analog
inputs
Configures P3.0-P3.1
and P3.3-P3.7 as
analog inputs
A P2.0 0
D P2.1 1
A P2.2 2
A P2.3 3
D P2.4 4
D P2.5 5
D P2.6 6
D P2.7 7
A P3.0 8
A P3.1 9
D P3.2 10
A P3.3 11
A P3.4 12
A P3.5 13
A P3.6 14
A P3.7 15
...
Figure 13.2. Auto-Scan Example
Scans on channels
not configured as
analog inputs result
in indeterminate
values that cannot
trigger a CS0
Greater Than
Interrupt event
13.4. CS0 Comparator
The CS0 comparator compares the latest capacitive sense conversion result with the value stored in
CS0THH:CS0THL. If the result is less than or equal to the stored value, the CS0CMPF bit(CS0CN:0) is set
to 0. If the result is greater than the stored value, CS0CMPF is set to 1.
If the CS0 conversion accumulator is configured to accumulate multiple conversions, a comparison will not
be made until the last conversion has been accumulated.
An interrupt will be generated if CS0 greater-than comparator interrupts are enabled by setting the ECS-
GRT bit (EIE2.1) when the comparator sets CS0CMPF to 1.
If auto-scan is running when the comparator sets the CS0CMPF bit, no further auto-scan initiated conver-
sions will start until firmware sets CS0BUSY to 1.
A CS0 greater-than comparator event can wake a device from suspend mode. This feature is useful in sys-
tems configured to continuously sample one or more capacitive sense channels. The device will remain in
the low-power suspend state until the captured value of one of the scanned channels causes a CS0
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Rev. 0.3