June 2013 DocID018933 Rev 2 1/18

AN3413

Application note

STM32L1x current consumption measurement

and touch sensing demonstration firmware

Introduction

This application note provides an overview of the demonstration firmware delivered with the

STM32L-DISCOVERY and 32L152CDISCOVERY evaluation boards. It allows you to

explore the rich set of power saving modes available in the STM32L1x microcontroller and

use the STM32L1xx DISCOVERY embedded IDD measurement circuit to demonstrate the

real capabilities of the Ultra low power microcontroller STM32L1x.

The demonstration application does not require any additional hardware. Once the

STM32L1xx DISCOVERY is powered-up through a USB cable connected to the host PC,

the application is ready to display the STM32L1x power consumption of each low-power

mode selected by the user.

In addition the demonstration firmware allows you to explore the touch sensing capabilities

of the STM32L1x microcontroller demonstrated by sensing the linear touch sensor or the set

of four touchkeys.

Reference documents

The current consumption measurement and touch sensing demonstration firmware is

included in the STSW-STM32072 STM32L1 discovery firmware package available from

http://www.st.com.

• STM32L1 discovery kits: STM32L-DISCOVERY and 32L152CDISCOVERY (UM1079)

• Getting started with software development toolchains for the STM32L-DISCOVERY and

32L152CDISCOVERY board (UM1451)

The above documents are available at http://www.st.com.

Table 1 lists the microcontrollers, evaluation tools and software concerned by this

application note.

Table 1. Applicable products, evaluation tools and software

Type Part numbers

Microcontrollers STM32L1 Series

Evaluation tools STM32L-DISCOVERY, 32L152CDISCOVERY

MCU software STSW-STM32072

www.st.com

Contents AN3413

2/18 DocID018933 Rev 2

Contents

1 Application description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.1 Used hardware components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2 STM32L1xx DISCOVERY hardware settings . . . . . . . . . . . . . . . . . . . . . . . 3

1.3 Application schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.4 Application principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.4.2 I

measurement principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.5 Getting started with the application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.5.1 Demo mode - Touch sensing demonstration and I

measurement . . . . 6

1.5.2 Bias current record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.5.3 Manufacturing test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.6 Low power modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2 Software description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.1 STM32L1x peripherals used by the application . . . . . . . . . . . . . . . . . . . . 10

2.2 STM32L1x standard firmware library configuration . . . . . . . . . . . . . . . . . .11

2.3 Application software flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

2.3.1 Main application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.3.2 Demo mode (I

measurement) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17