I2C總線數據傳輸應用研究（硬件部分）

電子機電論文編號:JD505 論文字數:8844,頁數:18

目錄
摘要 I
Abstract II
第1章 緒論 3
1.1 I2C總線介紹 3
1.2 I2C總線特征 3
1.2.1 I2C總線的優點 3
1.2.2 I2C總線在系統開發中的作用 4
1.2.3 I2C總線的一般應用特性 4
1.3 課題指導思想 5
1.4 課題設計任務和要求 5
1.5 論文結構 6
第2章 I2C總線協議 7
2.1 起始和停止條件 7
2.2 響應 7
2.3 仲裁和時鐘發生 8
2.3.1 同步 8
2.3.2 仲裁 9
2.4 七位的地址格式 10
2.5 本章小節 11
第3章 系統設計思想及主要應用器件 13
3.1 系統設計的總體思想 13
3.2 系統硬件簡介 13
3.2.1 硬件設計思想 13
3.2.2 硬件構成 14
3.3 系統主要器件 14
3.3.1 PCF8591 14
3.3.2 PCF8574 15
3.3.3 LCD 16
3.3.4 E2PROM 18
3.4 模塊設計 18
3.4.1 鍵盤模塊 18
3.4.2 溫度采集模塊 21
3.4.3 LCD控制模塊 22
3.4.4 E2PROM 23
3.5 本章小結 23
第4章 系統軟件設計 25
4.1 系統軟件設計要解決的問題 25
4.2 系統軟件模塊 25
4.2.1 單片機擴展I2C總線 25
4.2.2 A/D轉換模塊 28
4.2.3 鍵盤 29
4.2.4 LCD顯示模塊 32
4.2.5 E2PROM的讀寫 34
4.3 本章小節 36
結論 37
謝辭 39
參考文獻 39

摘要
I2C總線是Philips公司推出的串行總線，整個系統僅靠數據線（SDA）和時鐘線（SCL）實現完善的全雙工數據傳輸，即CPU與各個外圍器件僅靠這兩條線實現信息交換。I2C總線系統與傳統的并行總線系統相比具有結構簡單、可維護性好、易實現系統擴展、易實現模塊化標準化設計、可靠性高等優點。
本論文主要闡述了用單片機擴展的I2C總線與各種帶有I2C總線器件之間的數據傳輸問題。本設計采用AT89S51單片機的兩個I/O口擴展I2C總線，整個系統由溫度傳感器，信號采集電路、鍵盤、顯示電路、E2PROM讀寫電路構成。本系統可以采集周圍環境溫度，也可以通過鍵盤設置警界溫度，便在LCD上顯示環境溫度和警界溫度。單片機通過I2C總線可以讀寫E2PRPOM，便顯示存儲內容。
硬件方面，周圍環境溫度的測量采用AD590溫度傳感器，信號采集的A/D模塊采用了帶有I2C接口的飛利浦公司的PCF8591芯片；鍵盤、顯示分別采用了點觸式按鍵和帶有字庫128*64LCD顯示.由于沒有找到帶有I2C接口的LCD，我們同樣采用了帶有I2C接口的飛利浦公司的PCF8574芯片，用于控制LCD顯示。外存擴展我們采用E2PROM芯片，是容量為4K的AT24C04。軟件設計采取了流行的模塊化編程方法和模塊調試，軟件程序的開發全部采用C語言。其主要包含的程序有：主程序、I2C擴展程序、鍵盤掃描子程序、A/D采樣子程序、LCD顯示子程序等。
本設計的優點是簡單的兩線串行I2C總線將互聯減到最小，因此IC的管腳更少而且PCB的線路也減少，使硬件效益最大電路最簡單。

關鍵詞：I2C總線，串行總線，總線擴展

I2C BUS DATA TRANSMISSION APPLIED RESEARCH (HARDWARE PART)
Abstract
The I2C bus is the serial bus which Philips corporation promotes. The overall system only depends on the data line (SDA) and the clock line (SCL) realizes the consummation full-duplex data transmission. Namely CPU only depends on these two lines with each periphery component to realize the exchange of information. The I2C bus system compares with the traditional parallel bus system has the simple structure, the good maintainability, easy to realize the system to expand, realize the modular standardization design, the reliable higher merit.
The present paper mainly elaborated the data transmission question between the I2C bus components by the I2C bus which expands by single chip microcomputer. This design uses AT89S51 single chip microcomputer's two I/O mouth to expand the I2C bus. Overall system is constituted by temperature sensor, signal gathering electric circuit, keyboard, display circuit, E2PROM reading-writing electric circuit. This system may gather the environment temperature, may also establish the police temperature through the keyboard, then demonstrates the ambient temperature and the police temperature on LCD. The single chip microcomputer may read or write E2PRPOM through the I2C bus, then demonstrate the store content.
As far as the design of the hardware is concerned, we chose AD590 as the temperature sensor to gather the environment temperature, and chose Phillips Corporation's PCF8591 with the I2C bus mouth as A/D conversion to operate the gathering single, the touching style key as the keyboard, 128*64LCD with Chinese fonts as the monitor display. Because we has not found has I2C connection LCD, we also used Phillips Corporation's PCF8574 chip with the I2C bus in controlling the LCD demonstration. We use the E2PROM AT24C04 chip as the external memory, whose capacity is 4K. The development of software adopts the popular modularized structure and the modularized debug facilities. The design of software adopts assembly C language entirely. The primary program is composed of main program, I2C expansion procedure, keyboard scanning subroutine, A/D sampling subroutine, LCD demonstration subroutine and so on.
The advantage of the design is that the I2C bus make electric circuit more simple. therefore the chip’s pin will be less moreover the PCB line also to reduce, causes the hardware benefit biggest and electric circuit simple.

Key words: I2Cbus,data bus,bus expansion