Introduction to touch sensing with STM32

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1. How does it work

Touch Sensor is use in a one of HMI (Human Machine Interface)

Instead of using mechanical switch, using the finger touch on the surface

Three different methods

Capacitance switch

The electrode can be placed behind a non-conducted panel

Detect the capacitance change

Resistive touch switch

Two electrodes can be shorted by finger touch

Detect the short circuit

Piezo touch switch

By pushing/bending Piezo material, it generates the voltage

Detect the voltage change

TSC or Touch Sense Controller peripheral is based on the Capacitance switch

When human touch the surface of the sensor area, the capacitance changes

Basic TSC working mode descrition

File:2019-12-13 16 02 46-TSC Presentation.pptx - PowerPoint.png

TSC state machine

2. Getting started with STM32 and touch sensing

Article where it is explained how to start with STM32 TSC feature

3. Video related to touch sensing

All videos related to TSC

4. STM32 compliant with touch sensing

Maximum sensors per serie
	STM32L0	STM32L1	STM32L4	STM32L4+	STM32F0	STM32F3	STM32WB
Peripheral	TSC	Hardware assist	TSC	TSC	TSC	TSC	TSC
Group number	8	11	8	8	8	8	7
Channel number	32	48	32	32	32	32	28
Sampling capacitor number	8	11	8	8	8	8	7
Sensors number	24	37	24	24	24	24	21

Sensors per serie on LQFP64
	STM32L0	STM32L1	STM32L4	STM32F0	STM32F3
Peripheral	TSC	Hardware assist	TSC	TSC	TSC
Group number	8	10	4	6	6
Channel number	32	33	16	24	24
Sampling capacitor number	8	10	4	6	6
Sensors number	24	23	12	18	18

5. Specific tools

Links and explanations for TSC dedicated tools

6. ST Resources

AN5105 Getting Started with Touch control url
UM1913 Developing applications on STM32Cube with STMTouch touch sensing library url
AN4316 Tuning a STMTouch-based application url
AN4312 Guidelines for designing touch sensing applications with surface sensors url
AN4299 Guidelines to improve conducted noise robustness on STM32 series touch sensing applications url
AN4310 Sampling capacitor selection guide for MCU based touch sensing applications url
AN3960 ESD considerations for touch sensing applications url

7. Examples

The area where FAE's, collab... can put examples (linked to Github)