bq40z50 unresponsive

The 33 command will place the device into ROM mode. You can go to the Firmware screen and press the Execute button to return the firmware to normal mode.

Thanks, Tom! But that brings up three questions:

1. I'm using Battery Management Studio and it doesn't have an Execute button.

2. I found the section in the TRM about 0033 putting it into ROM mode (should've searched before hitting the Forum!), and it says that to enter ROM mode the part must be in FULL ACCESS and it's not. It's in Unsealed (Operation Status = 0x6181). So how did it do that?

3. I had been trying to change the Security Mode to Full Access just before this snafu, but I haven't been able to correctly figure out the sequence from the instructions. Can you explain the correct SMBus sequence?

Thanks!

Okay, I figured out #1 (The "Execute after programming" check-box  has to be unchecked.)

Were you able to get the device to return to Full Access Mode. I checked it on the bench and the command works.

I cannot get it back into Full Access.

(Are you using the Advanced Comm SMB section of the Battery Management Studio?)

If I use the Word Write with 0xFFFF (cmd = 0x00), the command goes through successfully, but when I Refresh the Register tab it still shows up as 0x6181.

If I use the Block Write with 0xFFFF (cmd = 0x00), an error is generated, and the Log message is "Timeout or unexpected response communicating with device."

I write the 0xFFFF twice, within the 4 second window, for both Word and Block writes.

I need some basic answers due to confusion in the TRM:

Page 66 says that Unsealed is when SEC1 & SEC0 are both cleared, but on page 86 it says it's 01 (respectively).

What are the SEC1 & SEC0 values for Sealed, Unsealed, and Full Access?

A-ha! So both pages in the 40z50 TRM are incorrect!

Thanks Tom!