C8051F80X_14 Datasheet, PDF (73/251 Pages) Silicon Laboratories – Mixed Signal ISP Flash MCU Family

C8051F80x-83x
SFR Configuration:
CS0CN = 0x80 ^{Enables Capsense0}
CS0CF = 0x70
CS0SS = 0x02
CS0SE = 0x0D
Enables Auto-scan
as start-of-
conversion source
Sets P0.2 as Auto-
scan starting channel
Sets P1.5 as Auto-
scan ending channel
P0MDIN = 0xF2 ^{Configures P0.3,}
P0.2, P0.0 as analog
inputs
P1MDIN = 0x04 ^{Configures P1.0-P1.1}
and P1.3-P1.7 as
analog inputs
A P0.0 0
D P0.1 1
A P0.2 2
A P0.3 3
D P0.4 4
D P0.5 5
D P0.6 6
D P0.7 7
A P1.0 8
A P1.1 9
D P1.2 10
A P1.3 11
A P1.4 12
A P1.5 13
A P1.6 14
A P1.7 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
greater-than comparator event to occur. It is not necessary to have CS0 comparator interrupts enabled in
order to wake a device from suspend with a greater-than event.
Note: On waking from suspend mode due to a CS0 greater-than comparator event, the CS0CN register
should be accessed only after at least two system clock cycles have elapsed.
For a summary of behavior with different CS0 comparator, auto-scan, and auto accumulator settings,
please see Table 13.1.
Rev. 1.0
73