用AT89C2051外加555芯片实现的成本低廉的冷冻柜或雪柜温度控制器项目，已投入批量生产。提供详细的源程序和硬件图纸。-AT89C2051 chip with 555 plus the cost of low freezer or refrigerator temperature control project, has been put into mass production. Provide a detailed source code and hardware drawings.