BQ27Z746EVM-047: The detected device is not compatible with this application!

Update:

I've also tried the following:

In the supported target dialog, select "Scan All" and [Finish], but after some time, it told me that no device could be found.

I then switched the interface cable from Port 2 (I2C) to Port 1 SMB) and repeated the process.  No change.

Question/Hypothesis: does the BQ27Z746EVM  require that a battery and / or battery charger be connected in order to be detected by bqStudio?

Update #2:

Looking at the schematic for the BQ27Z746EVM, I see that the EV2400 <=> BQ27Z746EVM cable doesn't power VDD to the BQ27Z746EVM.  So evidently the BQ27Z746EVM requires at least a battery and/or a charger to be connected.

But even after connecting a cell and measuring 3.5 v on VDD, the device still is not recognized / detected by bqStudio.

Update #3:

I've confirmed that the EV2400 is communicating something to the BQ27Z746EVM, but it's not clear that the BQ27Z746EVM is responding:

Hello Robert,

Try again but holding down the CHGR wake button. Or apply a voltage to PACK. Right now, its likely the FETs are open and it is in shutdown.

thanks,

Alex M.

Hopeful, but no joy.  I connected the PACK terminals to my battery controller.  It chose to output only 0.75V, but when I held down the CHGR WAKE button, it did in fact close the FETS, and I measured 3.5V on the pack terminals (same as on the battery terminals) as long as I held the WAKE button.  When  I released it, it drifted back to 0.75V.

So, holding it continually, I launched bqStudio and scanned for the BQ27Z746EVM.  I even tried "scan all" -- my 'scope told me that it was probing all the addresses, but I never saw a response from the BQ27Z746EVM.

I'm open to more suggestions!

A colleague asks: is it possible for the device firmware to get into a locked state such that it won't respond to I2C requests?

Hi Alex:

If you have a power supply, I would suggest setting the pack voltage to 3.5V or so and try again, the button works just as well but its easier to not have to hold it down.

I do have a spare supply, but I *was* holding the button down continually.  (In retrospect, since my battery is fully charged, I could just jumper CELL+ to PACK+ for the same effect).

Did you try manually selecting the correct .bqz file from the list when you tried with PACK voltage applied?

Yes -- that was the only option since the unit was not responding to I2C probes.  As I mentioned, while monitoring SCK and SDA, I could see the host / EV2400 probing the I2C bus, but never saw a response from the BQ27Z746EVM.  I tried both auto-detect and "scan everything" -- neither elicited a response.

Also, this gauge has an enable pin. Make sure your EVM is configured so that pin is grounded or you hit the button.

Just to make sure: are you referring to the ENAB- pin (pin D2 on the package)? That might be it -- I left the jumpers unmodified from their defaults.  But I see that I need to install a jumper on J14 or hold the ENAB WAKE button (NOT the CHGR WAKE button that you mentioned earlier).

So I tried that:

- jumper CELL+ to PACK+ and verify a constant 3.57V there

- hold down ENAB WAKE continually for the following steps

- launch bqStudio

- since "Auto Detected Devices" = none, I selected "gauge" and "1746_0_01-bq27z746.bqz" from the list.

- I select scan all from the list.

- click [Finish] and watch the I2C bus.  I see it cycling through addresses from 0x00 to 0x3f, but no response from the unit.

- Launch bqStudio anyway, and observe that the bqStudio window initially launches with SOME green cells, but after a moment they all go gray.

When I monitor I2C bus activity, I see the app periodically issue an I2C write to address 0x0B, but no response from the device.

So despite my efforts, it still appears that the device is not responding to I2C requests.

Hello Robert,

The procedure sounds fairly thorough and I believe it should work. I will try to recreate this on my own EVM. The only things I can suggest to check in the meantime are to measure the current draw of the device to verify its state, and to ensure you are running the latest test build of BQstudio. Based on the version you listed earlier, it sounds like it is correct though (and the no I2C response sounds like the gauge is shutdown). 

Enable can be used to wake the device instead of applying a startup voltage for lower voltage operation. In your case, it shouldn't actually be necessary, but it was worth trying to check. 

In addition, I would suggest double-checking all of the connections, jumpers, and test points like VDD/PACK to see if the values are what you expect. I have had issues where the GND/CELL- connection was bad and it caused a similar issue. Let me know if you find anything/solve it, but expect a follow up from me on Tuesday next week. 

thanks,

Alex M.