1. What is Touch Sensing
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
2. Getting started with STM32 and touch sensing
Application Note AN5105 summarize all information regarding Touch Sensing Controler usage.
This application note explain step by step how to handle touch sensor using STM32F072BDISCO and STM32L0538DISCO discovery boards.
For more information on STM32 Discovery boards --> Click here
To get AN5105 Getting Started with Touch control --> Click here
All videos related to TSC
4. STM32 compliant with touch sensing
4.1. Maximum sensors number on STM32 series
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 |
4.2. Maximum sensors number on LQFP64 packages
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)
- Low power F0, L4 and WB
software examples for F0 TBD
software examples for L4 TBD
software examples for WB TBD
- Autocalibration
software examples TBD
- Frequency hopping
software examples TBD
- FTB management
software examples TBD
- Noise immunity improvement
software examples TBD