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90 lines
2.5 KiB
90 lines
2.5 KiB
\section{Touch Sense Unit}
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The touch sensing unit provides an access to the \gls{TSC} peripheral, explained in \cref{sec:theory_touch}. The unit configures the \gls{TSC} and reads the output values of each enabled touch pad. Additionally, a threshold-based digital input function is implemented to make the emulation of touch buttons easier. The hysteresis and debounce time can be configured in the configuration file or set using a command. The threshold of individual pads must be set using a command.
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\subsection{Touch Sense Configuration}
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\begin{inicode}
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[TOUCH:touch@11]
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# Pulse generator clock prescaller (1,2,4,...,128)
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pg-clock-prediv=32
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# Sense pad charging time (1-16)
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charge-time=2
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# Charge transfer time (1-16)
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drain-time=2
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# Measurement timeout (1-7)
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sense-timeout=7
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# Spread spectrum max deviation (0-128,0=off)
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ss-deviation=0
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# Spreading clock prescaller (1,2)
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ss-clock-prediv=1
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# Optimize for interlaced pads (individual sampling with others floating)
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interlaced-pads=N
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# Button mode debounce (ms) and release hysteresis (lsb)
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btn-debounce=20
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btn-hysteresis=10
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# Each used group must have 1 sampling capacitor and 1-3 channels.
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# Channels are numbered 1,2,3,4
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# Group1 - 1:A0, 2:A1, 3:A2, 4:A3
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g1_cap=
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g1_ch=
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# Group2 - 1:A4, 2:A5, 3:A6, 4:A7
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g2_cap=
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g2_ch=
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# ...
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\end{inicode}
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\newpage
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\subsection{Touch Sense Events}
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\begin{cmdlist}
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0 & \cname{BUTTON\_CHANGE}
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The binary state of some of the capacitive pads with button mode enabled changed.
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& \begin{cmdpld}
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\cfield{u32} binary state of all channels
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\cfield{u32} changed / trigger-generating channels
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\end{cmdpld} \\
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\end{cmdlist}
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\subsection{Touch Sense Commands}
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\begin{cmdlist}
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0 & \cname{READ}
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Read the raw touch pad values (lower indicates higher capacitance). Values are ordered by group and channel.
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& \begin{cmdreq}
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\cfield{u16[]} raw values
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\end{cmdreq} \\
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1 & \cname{SET\_BIN\_THR}
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Set the button mode thresholds for all channels. Value 0 disables the button mode for a channel.
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& \begin{cmdreq}
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\cfield{u16[]} thresholds
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\end{cmdreq} \\
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2 & \cname{DISABLE\_ALL\_REPORTS}
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Set thresholds to 0, disabling the button mode for all pads.
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& \\
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3 & \cname{SET\_DEBOUNCE\_TIME}
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Set the button mode debounce time (used for all pads with button mode enabled).
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& \begin{cmdreq}
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\cfield{u16} debounce time (ms)
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\end{cmdreq} \\
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4 & \cname{SET\_HYSTERESIS}
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Set the button mode hysteresis.
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& \begin{cmdreq}
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\cfield{u16} hystheresis
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\end{cmdreq} \\
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\end{cmdlist}
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