Car door pressure tester made with Atmega32 microcontroller

The door pressure tester is a portable handheld structure, which is composed of a special pressure test sensor and a test management system. It is specially used to test the closing force of subway vehicle passenger compartment doors, minimum obstacle detection, and door anti-pinch protection function detection. The equipment can set and record the number of door openings and closings, time, and test items. The system can automatically and effectively complete the test requirements and automatically record the test results to generate reports.

Vehicle doors, especially doors for high-speed vehicles such as trains, are products with high safety performance requirements. Their various performance indicators must be kept within a relatively safe range of values ​​to ensure the safe operation of the vehicle. This requires manufacturers to test these parameters not only during the product manufacturing process, but also during the inspection and maintenance of the product after it is put into use, as a reference information for the safe use of the product. For a long time, due to the lack of attention paid to the development of testing instruments in my country, the usual testing methods mainly rely on testers to assist with a variety of manual tools.

At present, the door pressure detection method mostly relies on the detection personnel to use manual tools for detection. The main defects of this detection method are: 1) The test device is bulky, inconvenient to carry and operate; 2) The test data must be recorded manually, and the exchange of information is inconvenient; 3) The test is based on manual experience, and the test accuracy is not guaranteed; 4) Poor safety; 5) Low test efficiency.

The portable door pressure detector developed in this paper is composed of a special pressure test sensor and a test management system. It is specially used to detect the closing force of subway vehicle passenger compartment doors, minimum obstacle detection, and door anti-pinch protection function detection. The equipment can set and record the number of door openings and closings, time, and test items. The system can automatically and effectively complete the test requirements and automatically record the test results to generate reports. The equipment uses a USB operation transfer interface.

1 Overall Plan

This system uses ATmega32 as the main control chip of the main control board. The design includes pressure acquisition system, control interface and display system, power supply system, data storage and data import module, and abnormal alarm module. The main system block diagram is shown in Figure 1.

2 ATmega32 Introduction

Atmega32 MCU is an 8-bit MCU based on AVR RISC and low-power CMOS. Since one instruction is executed in one clock cycle, Atmega32 MCU can achieve a performance close to 16M IPS/MHz. Its main performance is as follows:

1) High performance, low power consumption 8-bit AVR microcontroller;

2) Advanced RISC reduced instruction set architecture, 130 powerful instructions, most of which are executed in a single clock cycle, and an on-chip hardware multiplier with an execution time of two clock cycles;

3) On-chip 32K bytes of online self-programming FLASH (erasable 1,000 times), 1024 bytes of EEPROM (erasable 100,000 times), 2K bytes of internal SRAM, and program encryption function;

4) Two 8-bit timer/counters with prescaler and one comparison mode, one 16-bit timer/counter with prescaler and comparison mode, capture mode, counting function, and real-time clock (RTC) with independent oscillator; 4 PWM channels; 8-channel A/D converter, including: 6 channels with 10-bit conversion accuracy and 2 channels with 8-bit conversion accuracy; programmable watchdog timer with on-chip crystal oscillator; on-chip analog comparator;

5) Typical microcontroller features: power-on reset and programmable undervoltage detection; internally calibrated RC oscillator; 18 external and internal interrupt sources;

6) High speed and ultra-low power consumption.

In ATMEL's microcontroller family, ATmega32 is a very special microcontroller. It adopts Harvard structure, integrates large-capacity memory and rich and powerful hardware interface circuits inside the chip, has high speed, low power consumption and low cost, and is very suitable for designing portable door pressure detector devices.