Introduction - If you have any usage issues, please Google them yourself
Its function is to: 1. Reads the current temperature value. 2 buttons to adjust the alarm temperature upper and lower limits. Temperature on the line the first key, enter the adjustment mode, the second key temperature plus third key temperature less, click the first button, enter the temperature off the assembly line adjustment mode, the second key temperature plus the third a key temperature key, and click the first button, display the current temperature normal. Enter the alarm temperature upper and lower limits regulation, red light, display the current temperature, the green light. When the current temperature exceeds the upper limit of temperature or below the lower limit temperature buzzer alarm and flashing yellow light. It should be noted that, under normal circumstances, DQ pin should have a pull-up resistor to pull the high level, but I found through observation, the initial state, the 89C52 pin high, therefore I will pull- resistor removed 1820 microcontroller normal commun