LPC845M301JHI48K IIC communication with 9th ACK Signal abnormal

TeemoLi · ‎08-21-2023

LPC845M301JHI48K use hardware IIC configure. Master IIC: LPC845M301JHI48K

100Khz frequency. 4.7K pull-up resistor.

The IIC communication on 9th ACK Signal abnormal. Please refer to the below picture.

What causes this problem to occur ? This is episodic.

How to improve the ACK signal ?

EdwinHz · ‎08-21-2023

This is a very odd behavior. Do correct me if I'm wrong in my assumption, but I presume you are seeing this behavior when transmitting frames from the master to the slave, which would mean that the slave device is not sending back the ACK correctly. That would mean that you are seeing this behavior because of your slave device, not the LPC. You should be able to corroborate this by testing the LPC as slave, and sending 9 frames to it repeatedly. Make sure your slave device is capable of receiving more than 8 bytes of information at a time. It might not be capable and this could be the reason why it isn't able to send back a proper ACK signal.

BR,
Edwin.

View solution in original post

EdwinHz · ‎08-21-2023

Hi @TeemoLi,

This is a very odd behavior. Do correct me if I'm wrong in my assumption, but I presume you are seeing this behavior when transmitting frames from the master to the slave, which would mean that the slave device is not sending back the ACK correctly. That would mean that you are seeing this behavior because of your slave device, not the LPC. You should be able to corroborate this by testing the LPC as slave, and sending 9 frames to it repeatedly. Make sure your slave device is capable of receiving more than 8 bytes of information at a time. It might not be capable and this could be the reason why it isn't able to send back a proper ACK signal.

BR,
Edwin.