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RM0365
Touch sensing controller (TSC)
455
The voltage variation over the time on the sampling capacitor C
S
is detailed below:
Figure 129. Sampling capacitor voltage variation
19.3.3
Reset and clocks
The TSC clock source is the AHB clock (HCLK). Two programmable prescalers are used to
generate the pulse generator and the spread spectrum internal clocks:
•
The pulse generator clock (PGCLK) is defined using the PGPSC[2:0] bits of the
TSC_CR register
•
The spread spectrum clock (SSCLK) is defined using the SSPSC bit of the TSC_CR
register
The Reset and Clock Controller (RCC) provides dedicated bits to enable the touch sensing
controller clock and to reset this peripheral. For more information, please refer to
.
Table 107. Acquisition sequence summary
State
G1_IO1
(electrode)
G1_IO2
(sampling)
G1_IO3
(electrode)
G1_IO4
(electrode)
State description
#1
Input floating
with analog
switch closed
Output open-
drain low with
analog switch
closed
Input floating with analog switch
closed
Discharge all C
X
and
C
S
#2
Input floating
Dead time
#3
Output push-
pull high
Input floating
Charge C
X1
#4
Input floating
Dead time
#5
Input floating with analog switch
closed
Input floating
Charge transfer from
C
X1
to C
S
#6
Input floating
Dead time
#7
Input floating
Measure C
S
voltage
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