Having a problem initializing the MC33771

[rogerdavis_mitr]

I have written code to talk to the MC33771 part. After initialization of the INIT register I can read registers and get what appears to be good data with valid CRCs without fail for what appears to be exactly 1 second and then I begin getting invalid replies.  I'm using the SPI port. What I'm looking for is any ideas as to whether the 1 second timeout is normal or is a clue for what I am doing wrong.  Shouldn't the chip keep responding indefinitely after proper initialization?

Investigating further I figured out a little bit more.  As mentioned above, I can do an initialization sequence and immediately follow that with good reads.  If I wait a second, subsequent reads are invalid. They are all 0's with what is probably a good crc on it, but useless as far as reading a register. What I learned just now is that, after it starts failing, if I issue another read to the INIT register but using the CID-unassigned value of all 0's, it responds properly. The INIT register is a good place to experiment because it can be read using CID=0 when unassigned and CID=xx after assigning the address to it. So, it's as if it has forgotten that I assigned the device with the CID address in the init sequence if I wait long enough.  Under what circumstances can the part forget it's CID address?

[veerajuvh619]

Hi sir,

I have one issue regarding in daisy chain connection of MC33771. How to read voltage reading from particular AFE (out of 2 AFE). How to differentiate between two AFE is there any criteria to enable AFE one after the other continuously.

In daisy chain connection if we remove battery of one AFE then next to that AFE will work or not.

Regards,

Veeraju V Hallikeri  

[climbhuang]

Hi，Tomas,

we have some problems about MC33771 initializing, it always failed with a return  value CRC_STATUS. 

The second question is about SPI communication, we use the driver software from BCC_S32K144_Monitoring  NXP official website, we can detect the signal of CSB , CLK , but none of  DATA_OUT, so we are looking foward for your suggestion.

At last , we don't  have the datasheet above you use, hope you can provide  a download address~

appreciate for your reply~

[TomasVaverka]

Hi Roger,

It sounds like COM timeout reset which is enabled by default:

Best regards,

Tomas