TI Cup 2019 National College Student Electronic Design Competition Question F-Paper Counting Display Device

Design and produce a paper counting display device. Two parallel plates (plate A and plate B) are connected to the measurement display circuit through wire a and wire b respectively. The device can measure and display between plate A and plate B. number of papers in between.

Introduction and demonstration video link: https://www.bilibili.com/video/BV1Sf4y1r7wQ

Since there is no buzzer, the LED flashing is used instead of the buzzer sound in the video. If you need to change to a buzzer, you only need to use an active buzzer, a transistor and a resistor, and control it through a GPIO.

Hardware introduction

The project is built using STM32F103C8T6 core board, OLED module and FDC2214 module.

For a detailed introduction to the FDC2214 module, please see the link: https://oshwhub.com/Mobyw/FDC2214RGHT

Wiring:

Onboard resources:

Mechanical structure

Made of plastic clips and copper sheets. The copper sheets are 0.8mm thick T2 copper plates. Taobao customization of 50*50mm is about 18 yuan.

When welding wires, you need to be careful to wrap the exposed parts of the wires well so as not to short-circuit. If you use a soldering iron, you may not be able to solder it due to rapid heat dissipation. You need to use a heat gun or an aluminum alloy PTC heating plate.

Software introduction

See the attachment or GitHub page for the software: https://github.com/Moby-C/NUEDC_2019_F_Paper_Counting

Developed using Keil, based on the SYM32F1 standard peripheral library.

Software modification method :

Modify the OLED screen pin definition : oled.hmodify the macro definition in and modify it accordingly in oled.cthe OLED_Initfunction.

Modify the LED pin definition : oled.hmodify the macro definition in and modify it accordingly in oled.cthe OLED_Initfunction.

Modify the KEY pin definition : key.hmodify the four macro definitions of KEY_PORT, KEY_PIN, KEY_CLKand in.KEY

Modify the maximum number of measuring papers : main.cmodify MAXSIZEthe macro definition in.

Precautions

During calibration and measurement, it is necessary to frequently short-circuit the two plates to prevent the charging of the capacitor from causing deviation in the measurement results.

When the number of sheets is less than 30, the measurement accuracy is higher than 95%. When the number of sheets is large, a deviation of one sheet may occur. Since the mechanical structure is relatively simple, if you want to improve the accuracy, you can optimize some mechanical structures and increase the number of measurements (20 measurements in the program).