MC33771B - communication

[Patrick_Pavle]

Dear Community, 

I use the MC33664 and one MC33771B. Unfortunately, I am not getting any feedback from the MC33771B. This should at least send back an echo, i.e. a write command, via the TPL line if it is correct? 

First I send the wake-up sequence where only the CSB_TX is set to LOW and HIGH, whereby the times must be observed.

Then I send a software reset global frame that looks like this:  0x8010, 0x03, 0x03, 0xF6 

After reset I wait at least 5ms. Is it allowed to exceed 5ms? 

After I try to initialize the mc33771b: 0x0031, 0x01, 0x02, 0x04

Finally, i send a dummy no operation command.

However, on the oscilloscope you can only see the frames that I send and no feedback from the MC33771B on the TPL, RDTX-/RDTX+

best regards,

Patrick 

[TomasVaverka]

Hello Patrick,

Could you please share your schematic to make sure there is no issue in HW configuration and the TPL signals?

Typically you firstly need to assign a CID to all the BCC in the chain, but you can get a response by sending a read request for the INIT register to CID 0 when the BCC is not yet initialized (with a CID = 0).

Make also sure that the MC33664 is enabled and check that the TPL signals are correct.

Note that the MC33771B can only communicate with TPL1 protocol and the commands should be built based on a 40bits message as described in the datasheet.

I would also recommend you to look at our BCC software driver and the AN12084 – “MC3371/MC33772 Programming Guide”.

BR, Tomas