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LPI2C bus stuck if NACK received

Question asked by Han Niu Employee on Mar 26, 2020
Latest reply on Apr 15, 2020 by Alina Banica

Hi, everyone,


I am supporting customer CA on LPI2C, and  found LPI2C will be stuck( SDA and SCL are hold low) with baudrate 100KHz when a NACK is received after writing an incorrect address to slave node. And I use PD driver API LPI2C_DRV_MasterSendDataBlockingdata() to send data, and the phenomenon only occurs when set SDK optimization level -O1 which is default setting. I test the issue using our SDK RTM3.0.0 demo project named "lpi2c_master_s32k144", the IDE is S32DS.ARM.2018.R1 and the EVB is S32K144EVB-Q100 with part number 700-29248 Rev A.  I suspected it maybe a SDK bug, because i also test the phenomenon with baudrate of 400KHz with different optimization (-O0 and -O1), SDA and SCL are all release after NACK received. 



According to the section 3.1. 6 in I2C-bus specification and user manual, it will lead to generate a NACK when no receiver is present on the bus with the transmitted address, so there is no device to respond with an acknowledge. In order to generate NACK, i use one S32K144 EVB as master and another as slave, and master send incorrect address to slave node. The following two images are I2C bus timing sequence, respectively corresponding to different optimization image Optimization Level None(-O0) and Optimization Level Optimize(-O1) and baudrate is 100KHz. 


   image 1.  Optimization Level None(-O0)


   image 1.  Optimization Level Optimize(-O1)


Could anybody help check whether it is a SDK bug? 

And the attach is test demo project.



Han Niu