【正文】 將節(jié)點 4 的濕度報警上限值設(shè)置為 85%，當實時濕度為 89%時，是否報警一欄顯示為是，并開始閃爍。 系統(tǒng)準確性測試 采用溫濕度計 于 20xx 年 4 月 24 號 12： 00 時采集 三處節(jié)點 的 溫濕度，如表 5 所 示。其次調(diào)試溫濕度監(jiān)測電路。 5 硬件電路 硬件制作 首先是打印電路板 ， 將繪制好的 電路板 用轉(zhuǎn)印紙打印出來，并 裁剪覆銅板，再將 打印好的 電路板 裁剪成合適大小，把印有電路板的一面貼在覆銅板上，對齊好后把覆銅板 14 放入熱轉(zhuǎn)印機，放入時保證轉(zhuǎn)印紙沒有錯位。如果在有效應(yīng)答時間范圍內(nèi)收到應(yīng)答信號，則認為溫濕度信息成功發(fā)送到了接收端，此時狀態(tài)寄 存器的 TX_DS位置高并把數(shù)據(jù)從 TX_FIFO 中清除掉；如果在設(shè)定時間范圍內(nèi)沒有接收到應(yīng)答信號，則重新發(fā)送數(shù)據(jù)。上配置 寸的 TFTLCD。 AM2301 采用單總線接口，其中 DATA 數(shù)據(jù)口用于微處理器與 AM2301 之間的 通訊和同步，采用單總線數(shù)據(jù)格式，一次通訊時間 5ms 左右，具體格式如下，當前數(shù)據(jù)傳輸為 40bit，高位先出。 nRF24L0l 所有的配置字都由配置寄存器定義，這些配置寄存器可通過 SPI 口訪問。 TX_PLD 必須在 CSN 為低時連續(xù)寫入，而 TX_ADDR 在發(fā)射時寫入一次即可，然后置為高電平并保持至少 10μs，延遲 130μs后發(fā)射數(shù)據(jù)。單片機最小系統(tǒng)如圖 2 所示。其中采集溫度的精度為 ? C? ，采集相對濕度的精度為 ? 3%。 無線通信模塊方案 方案一：采用 GSM(Global System for Mobile)模塊進行通信， GSM 模塊需要借助移動衛(wèi)星或者手機卡，雖 然 能夠遠距離傳輸，但是其成本較大、且需要內(nèi)置 SIM(Subscriber Identity Module)卡，通信過程中需要收費，后期成本較高。 然而， 傳統(tǒng)的人工測試方法費時費力，效率低，且測試的溫度及濕度誤差大，隨機性大 (王明明等， 20xx)；而有線 方式的 測溫濕 度系統(tǒng) 存在著 不穩(wěn)定性，且 布線復(fù)雜，線路容易老化，線路故障難以排查，設(shè)備重新布局需要重新布置等問題。因此采用無線傳輸溫濕度信息尤為必要。 關(guān)鍵字： ATmega16 AM2301 無線傳輸 nRF24L01 Wireless Temperature and Humidity Monitoring System in Barn Shi Jianzhu (College of Engineering, South China Agricultural University, Guangzhou 510642, China) Abstract:Temperature and humidity is a very important parameter. In many places, such as the industrial, medical, and military, you need the temperature and humidity measurement device to monitor temperature and humidity. Direct wiring measurement does not meet the requirements, especially in some environments, such as, harsh industrial environments and outdoor environments. Therefore, the wireless transmission of temperature and humidity information is particularly necessary. At present, some devices can be used to monitor wireless temperature and humidity, but the price is the biggest drawback, the price is too high. The system must be stable, realtime and low power consumption in actual control. Therefore, the design of a lowpower consumption wireless temperature and humidity monitoring system makes sense. This paper presents a solution for wireless data transmission, the program is based on the nRF24L01 to design the monitorint system of wireless temperature and humidity. The system uses the traditional microcontroller ATmega16 and digital temperature and humidity sensor AM2301 to form multipoint, realtime wireless temperature and humidity monitoring system. Through a simple wireless munication protocols, bring about reliability and power balance. The system is a remote wireless temperature and humidity monitoring system. The system uses wireless munication technology to build a distributed wireless sensor works. The temperature and humidity data acquisition and transmission based on sensor nodes, with a simple work, easy maintenance, low operation cost. The system can be applied to a large granary temperature and humidity monitoring. Key word: ATmega16 AM2301 Wireless Transmission nRF24l01 目 錄 1 前言 .......................................................................................................................................1 2 系統(tǒng)方案分析與選擇論證 ...................................................................................................1 系統(tǒng)最終方案 ................................................................................................................... 1 系統(tǒng)方案設(shè)計 ................................................................................................................... 2 主控芯片方案 ................................................................................................................ 2 無線通信模塊方案 ........................................................................................................ 2 溫濕度傳感器方案 ........................................................................................................ 3 顯示模塊方案 ................................................................................................................ 3 3 主要芯片介紹和系統(tǒng)模塊硬件設(shè)計 ...................................................................................4 ATmega16L8AI 單片機 .................................................................................................. 4 nRF24L01 無線模塊 ........................................................................................................ 5 nRF24L01 模塊電路圖 ................................................................................................. 5 nRF24L01 模塊接口電路 ............................................................................................. 5 nRF24L01 模塊供電電源 ............................................................................................. 6 nRF24L01 模塊工作模式 ............................................................................................. 6 nRF24L01 模塊工作原理 ............................................................................................. 7 nRF24L01 配置字 ......................................................................................................... 8 數(shù)字溫濕度傳感器 AM2301 .......................................................................................... 8 AM2301 概述 ................................................................................................................ 8 AM2301 接口及溫濕采集電路 .................................................................................... 9 AM2301 工作原理 ........................................................................................................ 9 顯示模塊 TFTLCD ....................................................................................................... 10 4 系統(tǒng)軟件設(shè)計 ......................