Introduction to touch sensing with STM32: Difference between revisions

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Latest revision as of 18:17, 21 May 2025↑

This page contains application examples, document references, tips and tricks and so on related to STM32 touch sensing.

1. What is touch sensing?↑

Touch sensors are used in HMIs (human-machine interfaces)

Instead of using mechanical switches, actuation is achieved by touching the finger touch on a surface.

There are three methods:

Capacitance switch:
- the electrode is placed behind a non-conductive panel
- the change in capacitance is detected
Resistive touch switch:
- two electrodes are bridged by the user's fingertip
- the resistance of the fingertip is detected
Piezo touch switch:
- a voltage is generated by pushing/bending a piezoelectric material
- the voltage change is detected

The TSC (touch sense controller) peripheral is based on the capacitance switch method - when a human touches the surface of the sensor area, the capacitance changes.

Basic TSC working mode description

2. Getting started with STM32 and touch sensing↑

Application note AN5105 summarizes all information regarding touch-sense controller usage.
This application note explain step-by-step how to handle touch sensors using STM32F072BDISCO^[1] and STM32L0538DISCO^[2] discovery boards^[3].

3. STM32 compliance with touch sensing↑

3.1. Maximum number of sensors on STM32 Series products↑

	STM32L0	STM32L1	STM32L4	STM32L4+	STM32L5	STM32F0	STM32F3	STM32WB	STM32WBA	STM32U0	STM32U5
Peripheral	TSC	Software assist	TSC	TSC	TSC	TSC	TSC	TSC	TSC	TSC	TSC
Groups	8	11	8	8	8	8	8	7	5	7	8
Channels	32	48	32	32	30	32	32	28	20	28	32
Sampling capacitors	8	11	8	8	8	8	8	7	5	7	8
Sensors	24	37	24	24	22	24	24	21	15	21	24

3.2. Maximum number of sensors on LQFP64 packages↑

	STM32L0	STM32L1	STM32L4	STM32L5	STM32F0	STM32F3	STM32U0	STM32U5
Peripheral	TSC	Software assist	TSC	TSC	TSC	TSC	TSC	TSC
Groups	8	10	4	8	6	6	6	4
Channels	32	33	16	30	24	24	24	14
Sampling capacitors	8	10	4	8	6	6	6	4
Sensors	24	23	12	22	18	18	18	10

4. STMicroelectronics resources↑

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

5. References↑

[1] STM32F072BDISCO

[2] STM32L0538DISCO

[3] STM32 Discovery Kits

[1]

[2]

[3]

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+{{DISPLAYTITLE:Introduction to touch sensing with STM32}}
 This page contains application examples, document references, tips and tricks and so on related to STM32 touch sensing.
 ==What is touch sensing?==
@@ Line 35: / Line 36: @@
   ! scope="col"  style=" text-align:center"  | STM32F3
   ! scope="col"  style=" text-align:center"  | STM32WB
+ ! scope="col"  style=" text-align:center"  | STM32WBA
+ ! scope="col"  style=" text-align:center"  | STM32U0
+ ! scope="col"  style=" text-align:center"  | STM32U5
   |-
   ! scope="row" | Peripheral
 | style=" text-align:center"  | TSC
 | style=" text-align:center"  | Software assist
+| style=" text-align:center"  | TSC
+| style=" text-align:center"  | TSC
+| style=" text-align:center"  | TSC
 | style=" text-align:center"  | TSC
 | style=" text-align:center"  | TSC
@@ Line 55: / Line 62: @@
 | style=" text-align:center"  | 8
 | style=" text-align:center"  | 7
+| style=" text-align:center"  | 5
+| style=" text-align:center"  | 7
+| style=" text-align:center"  | 8
   |-
   ! scope="row" | Channels
@@ Line 65: / Line 75: @@
 | style=" text-align:center"  | 32
 | style=" text-align:center"  | 28
+| style=" text-align:center"  | 20
+| style=" text-align:center"  | 28
+| style=" text-align:center"  | 32
   |-
   ! scope="row" | Sampling capacitors
@@ Line 75: / Line 88: @@
 | style=" text-align:center"  | 8
 | style=" text-align:center"  | 7
+| style=" text-align:center"  | 5
+| style=" text-align:center"  | 7
+| style=" text-align:center"  | 8
   |-
   ! scope="row" | Sensors
@@ Line 85: / Line 101: @@
 | style=" text-align:center"  | 24
 | style=" text-align:center"  | 21
+| style=" text-align:center"  | 15
+| style=" text-align:center"  | 21
+| style=" text-align:center"  | 24
   |}
@@ Line 97: / Line 116: @@
   ! scope="col"; style=" text-align:center" | STM32F0
   ! scope="col"; style=" text-align:center" | STM32F3
+ ! scope="col"; style=" text-align:center" | STM32U0
+ ! scope="col"; style=" text-align:center" | STM32U5
   |-
   ! scope="row" | Peripheral
 | style=" text-align:center"  | TSC
 | style=" text-align:center"  | Software assist
+| style=" text-align:center"  | TSC
+| style=" text-align:center"  | TSC
 | style=" text-align:center"  | TSC
 | style=" text-align:center"  | TSC
@@ Line 113: / Line 136: @@
 | style=" text-align:center"  | 6
 | style=" text-align:center"  | 6
+| style=" text-align:center"  | 6
+| style=" text-align:center"  | 4
   |-
   ! scope="row" | Channels
@@ Line 121: / Line 146: @@
 | style=" text-align:center"  | 24
 | style=" text-align:center"  | 24
+| style=" text-align:center"  | 24
+| style=" text-align:center"  | 14
   |-
   ! scope="row" | Sampling capacitors
@@ Line 129: / Line 156: @@
 | style=" text-align:center"  | 6
 | style=" text-align:center"  | 6
+| style=" text-align:center"  | 6
+| style=" text-align:center"  | 4
   |-
   ! scope="row" | Sensors
@@ Line 137: / Line 166: @@
 | style=" text-align:center"  | 18
 | style=" text-align:center"  | 18
+| style=" text-align:center"  | 18
+| style=" text-align:center"  | 10
   |}