Abstract: A portable nitrogen concentration detector based on the STC89C52 single chip microcomputer and an oxygen sensor is designed for the purpose of real-time detection of gas concentration in the gas regulating storage room. According to the principle that the concentrations of nitrogen and oxygen in the atmosphere is almost complementary when the rare gases are ignored, the monitoring of nitrogen concentration in grain storage rooms can be converted into monitoring oxygen concentration, which can ultimately be converted back to calculate the percentage of nitrogen concentration in the environment. When the nitrogen concentration percentage in the grain storage room is below the preset value of 97% , an audible and visual alarm function can be activated, while the nitrogen concentration percentage, temperature, and humidity information inside the grain storage room can be displayed in real-time. The hardware system includes signal acquisition circuits such as an oxygen sensor and a temperature and humidity sensor, signal conditioning circuits, analog-to-digital conversion circuits, an STC89C52 single chip microcomputer, and an audible and visual alarm unit. For software design, the C language and Keil development environment are selected. The experimental test results indicate that the detector can display environmental information in real-time and immediately trigger an alarm when the nitrogen concentration in the environment falls below the preset value of 97% , fulfilling its expected functions.

Key words: sensor, single chip microcomputer, detector