MC33771C Example Communication

[p0ly]

Hi,

I was wondering if there is any example TPL communication (with bit timings, message content, etc) I can send out from an MC33664 to induce a response from a MC33771C.

For context, I'm trying to interface with a Porsche Taycan 24V battery module, and I've got my MCU communicating SPI messages to an MC33664, and I see the pulse train on the RDTX pins as well as on the other side of the HM2103NL isolation transformer, and my logic analyzer sees the message I am sending mirrored on the receive SPI pins just fine. The problem comes when I try to connect this communication to the Porsche battery.

From my testing, the battery's power output is in perfect shape, so the onboard BMS should also be healthy, but I can't seem to find a message that will induce a response from the supposed onboard MC33771C. I've tried sending the wake-up message as is detailed in the datasheet (pull CSB_TX low for 21 us, high for 600 us, low for another 21 us, back to high), followed by the SPI frame converted to TPL "\x00\x01\x03\x00\x01\x56" (read, msg counter 0, device 0, register 3, master 0, 1 register, crc). The timings for this TPL message include a ~1.7 us delay after start of message, then 2 MHz pulses (250 ns gap between bits) and then a ~1.7 us gap before end of message. From what I've read on the datasheet, this should be a valid TPL frame, but I'm not seeing any response from the MC33771C, which leads me to believe I'm not sending valid message content. I've verified that the pulse encoding of my intended message is correct on the oscilloscope, so any help with this would be greatly appreciated.

If it helps, from what I've seen on other forums, the Porsche battery has a 4-pin pinout on the back of the battery, with both sets of two pins going into an HM2102NL, so that one set is used for MCU control, and the other is for daisy chaining more battery modules. I'm connected to the bottom two pins on the module, and see the RDTX waveform change a little when loaded with the battery TPL bus. The output of the HM2012NL then goes to an onboard MC33771C to access all the cell voltages and temps and whatnot.

I have included an image of my example TPL frame if it helps indicate if the message encoding is wrong (the pulse train does not include the string I mentioned above, this picture was from when I was first debugging the message encoding).

[guoweisun]

Hi 

Please see below link for the SDK about MC3377X with MC33664 by TPL communication.

MC33771C | 14-Channel Li-Ion Battery Cell Controller IC | NXP Semiconductors

Hope this could help you!

Thanks!

[p0ly]

Hi, and thank you for the quick response.

In the screenshot it appears to be under a secure tab which I don't have access to. Should I fill in the form to request access? For clarification, I'm not using the MC33664 development board so I hope that the PDF that would be provided would be for standalone setups.

[guoweisun]

Hi p0ly

You can directly contact with your local NXP distributor for acceleratingly 
request these documentations.

Distributor Network | NXP Semiconductors

The MC33664 EVB connection  method should be same with your own board.