由于IIC总线锁死引起保护装置异常的问题分析

Analysis of protective device error caused by IIC bus lockup

当保护装置采用IIC总线的器件时,可能出现由于IIC总线锁死而导致装置异常的问题。以采用IIC总线的RTC芯片和IIC总线的EEPROM芯片作为定值芯片的实际装置为例,从IIC的规范和装置的软硬件配合方面进行详细分析,发现由于RTC芯片的IIC总线锁死而引起装置定值芯片无法正常访问,最终导致装置无法正常运行。针对这个问题提出了两种解决方法:一是主器件补发SCK脉冲,以完成从器件的读操作周期,从而释放总线;二是采用具有IIC总线锁定保护功能的IIC器件。

When the IIC devices are used in a protective device, in some conditions, the protective device cannot work correctly. In this paper, the protective device with RTC and EEPROM devices based on IIC bus is taken as the example. The analysis is promoted from the IIC bus specification and the cooperation of software and hardware of the protective device. Through research, the reason for the device error is found. The IIC bus lockup of the RTC caused the setting device cannot be accessed and thus caused the protective device error. At last, two solutions are put forward. The first solution is to make the master device output several SCK pulses, so as to complete the read operation cycle of the slave device and release the IIC bus. The second solution is to adopt the devices with IIC bus lockup protection.