bq78pl116 Error Reading Data; open circuit?

There is an *undocumented* power sequence that has to be done. This file was given from a TI employee thru the forum a few months ago

5127.PowerSequence for bq78PL114_6.pdf

We had a whole lot of problems because we didn't follow this sequence. We were having some random but very frequent failures that are similar to what you are describing.

In other words: the chip cannot survive if the stack is incomplete.

Mathieu,

Thanks for you response.I am working with Drew, on this system. I think our issue might also be that we were not supplying power to the EVM that was not also powering the cell simulator. In fact, I can not find a diagram, or instructions on how to power the bq78pl116EVM on its own isolated power.  I am adding the error messages we are currently receiving when trying to connect via USB-to-GPIO and the bqWizard software.

Error Reading Parameters

"Communication error to hardware check power and connections to the hardware" will flash, then it will re-initialize and say "0 cells found" then will go back to error reading parameters.

Thanks for the help

In addition, we noticed something very interesting. When the Cell simulator was hooked up to the EVM, cells 3 and 4's voltages we approx. 2.5V, while the rest of the cells were around the 3.4V. When running the cell simulator not connected to the EVM we get an even distribution (to be expected) across all 8 cells.

Hope this helps diagnose our issue.

The simulator must use resistor close to 10ohm.

I do not understand the following : I think our issue might also be that we were not supplying power to the EVM that was not also powering the cell simulator

We are using 10ohm Resistors.

What I meant, is there is no isolated VSS and GND for the EVM board itself. It seems to be powered through the cell simulators Batt-/Batt+ connections. I was wondering if there were seperate power pins for the board that i was overlooking.

Is there any official answer known for this problem ,  error reading data "0 cells found" ? 

Does it solve the problem , changing the chip? We have purchased a bq78pl116EVM , but the chip on the EVM has a different footprint, than the bq78pl116 that is being sold . 

To keep everyone updated;

Today we swapped the chip-out with an extra bq78PL116 that we had ordered from TI. We are still getting the 0 cell found message, and more importantly (the error we believe is causing this) Error Reading Parameters.  We re-created the tmap file using the instructions in the quick start demo manual, used correct power sequencing, and double checked all resistor (cell simulator votages), and they all are correct.

Any other suggestions would be great.

If you using more than 4 cells, I would change the slaves used as well.

I believe the slaves are broken and not the main chip, since you can talk to it but you get nothing intelligent out of it. This is the meaning of the VLAN flag, usually

We are using 8 cell simulator, I will try to use only 4 cells, since I do not believe we have any bq78PL102 around to try swapping them.

Will post back with results

Update,

We finally got the board working again. It seems we needed to reset the bq78PL102s (slaves) that were on the board, and apparently that doesnt happen with a simple power cycle. I connected up a 4 cell system (cell simulator again) and attempted to read the data. I could not even recieve coms with the processor. Thinking it was a lost cause, i re-wired up the 8 cell simulator to test the coms. Behold, and working 8 cell found, system. Only problem now is it seems our resistors are getting a little too hot, and are causing the bq78PL116 to through an SOTD Flag, and blow the electronic Fuse. I'll be digging some more to see if i just need higher power resistors or if something else is going on.

Good luck, hope my finds help .

I guess it turns out nothing was fixed, and it was a fluke. Further testing showed that the 7 and 8 cell connections were swapped, and thats when we were getting 8 cells read. However, on correcting the wiring issue, we are now back to 0 cells read. We attempted to reset the bq78PL102s again using the same method mentioned above, but no such luck. Looks like the 0 cells read error is still an issue here.

Check the LDO pin at the master and the slaves. They should be 2.5V.

Typically I got some other voltage when the chip was dead.

Measuring the voltage on the LDO pins shows 2.5V. The unit was able to start up this morning, but there were countless errors mainly with the temperature readings. Previously before this issue occurred, we had no issue with cell temperatures reading over 30C even though the resistors themselves were extremely hot. Now we have a few readings constant at 90C and other sensors reporting anywhere from 45C to 80C. It seems like a sensor malfunction. Also, voltages for the 8 cells were not constant over the running time of the system. Eventually, the voltage just gave out on one of the cells and it dropped to 2.5V and the board lost communication. Any thoughts?

Has anyone solved the problem ? How can the problem still exist after changing the chips i dont get it.

Sercan