基于I^2C总线的I/O口扩展设计

Design of I/O port expansion based on I^2C bus

由于传统的NI-DIO驱动板卡能够驱动的I/O口数量比较有限,一般只应用在测试通道数比较少的实验场合。而在一般的大型环境试验中,要求能对多个产品同时测量。如果使用传统的DIO板卡测试,就会出现测量通道数量不够的情况。针对此类问题,提出了运用单片机与I/O扩展芯片PCA9554/A采用I2 C通信进行I/O扩展,上位机采用LabVIEW编程,界面友好、操作方便,在环境实验中起到了良好效果。

Since the traditional NI-DIO driver board can only drive limited number of I/O ports, it is always used in the test occasions, in which there are few testing channels under test. But in general large test, many products need to be measured in the same time. If the traditional NI-DIO driver board is used for testing, the number of test channels will be not enough. In the light of this, a way of I/O expansion is proposed, in which I2C bus communication between MCU and I/O ex- tension chip PCA9554/A is used. The LabVIEW is used for programming on the PC. It has friendly interface and easy opera- tion. A good result was achieved in environment test.