ST STM32F301 6 Series Reference Manual page 315

RM0366
Note: Gx_IOy where x is the analog I/O group number and y the GPIO number within the selected
group.
The surface charge transfer acquisition principle consists of charging an electrode
capacitance (C
capacitor (C
threshold (V
is a direct representation of the size of the electrode capacitance.
Table 52
1. States 3 to 7 are repeated until the voltage across C
same sequence applies to the acquisition of the other channels. The electrode serial
resistor R
Figure 88. Surface charge transfer analog I/O group structure
Electrode 1
R
C
V
X1
SENSOR
V
CS
Electrode 2
R
C
V
X2
SENSOR
Electrode 3
R
V
C
SENSOR
X3
) and transferring a part of the accumulated charge into a sampling
X
). This sequence is repeated until the voltage across C
S
in our case). The number of charge transfers required to reach the threshold
IH
details the charge transfer acquisition sequence of the capacitive sensing channel
improves the ESD immunity of the solution.
S
S1
Gx_IO1
Gx_IO2
C
S
S2
Gx_IO3
S3
Gx_IO4
RM0366 Rev 5
Touch sensing controller (TSC)
Analog
I/O group
reaches a given
S
reaches the given threshold. The
S
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