AN4073 datasheet(7/32 Pages) STMICROELECTRONICS

Part #	AN4073

Description	How to improve ADC accuracy when using STM32F2xx and STM32F4xx microcontrollers

PDF	32 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

Logo

7 / 32 page

DocID022945 Rev 5

7/32

AN4073

Firmware techniques for improving the conversion accuracy

Firmware techniques for improving the conversion

accuracy

2.1

Averaging

Averaging is a simple technique where you sample an analog input several times and take

the average of the results. This technique is helpful to eliminate the effect of noise on the

analog input or a wrong conversion.

2.1.1

Averaging of N ADC samples

When this method is used, it is better to collect the samples in multiples of 2 (N should be a

multiple of 2). This makes it more efficient to compute the average because you can do the

division by right-shifting the sum of the converted values. This saves CPU time and code

memory needed to execute a division algorithm (in Cortex-Mx, this takes 1 CPU cycle).

Figure 1. Graphical representation of averaging technique

This averaging technique is used to measure the voltage on one analog input pin. A total of

N conversions is considered and the average is calculated. This is done in a loop in the

firmware.

MS31175V1

Digital output

Average value

Number of

conversions

AN4073 Datasheet(PDF) 7 Page - STMicroelectronics