• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 65 subscribers
  • Views 2208 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SBS BatteryMode Command

John Treubig
Prodigy 220 points
Other Parts Discussed in Thread: BQ20Z90

Help me out with the SBS BatteryMode command.  I am attempting to use the BatteryMode 0x03 command to turn off Alarm Messages to the charger.  I have batteries with bq20z90 and bq2084 gauges and neither appears to shut down the alarms when I send the command to the gauge.  The attached I2C bus analyzer trace shows the gauges receive the command (note there is no *, meaning the last byte was ACKed), but aside from that, I'm clueless on what other requirement need to be met to shut off the alarm messages.

 

The only devices on the bus are the battery and an MSP430 that I'm using to send the BatteryMode command and receive messages to the charger (address 0x9).  Just to elaborate, I've set all three LSBits of the mode command just to see if I could shut off the charge command too.  The bottom trace shows the current of 500ma being sent out.

 

Please note the message requests to address 0x8 come from the gauge, and I don't know who/what they are trying to address/do.

TIA,

John

 

  • 0
    TI__Expert 6470 points

    John - you can use the BCAST bit in bq20z90 OpConfigB to turn off the broadcasts.

     For bq2084, all broadcasts can be disabled by setting SM (bit 2) in Pack Configuration (DF 0x28).

  • 0 in reply to Doug Williams4811
    Prodigy 220 points

    Doug,

    Thanks for your reply and good suggestion, as turning off BCAST would stop all broadcasts.  I am not able to take advantage of turning of BCAST as we are using the battery's broadcasts to control our charger IC (MAX1645).  We have found that the batteries work fine, except when they get low enough to alarm with a TERMINATE_ DISCHARGE_ALARM (TDA).  Our difficulty is that the MAX1645 will begin to charge and upon seeing a TDA, it will suspend charging waiting for host intervention.  My desire is to use the BatteryMode command to temporarily suspend ALARM_MODE so I can keep the charger going.

    The trace below would indicate that the gauge (bq2084) is needing additional information to invoke this feature (Note the Alarm output 09169F0A immediately following the 0B030300).  Not sure what that information would be.  

    Since we don't have a device receiving the broadcasts to the host  (note the gauge is not able to address device 08 shown in the trace below) I'm not sure if this is a contributing factor.  

    Look forward to your suggestions.

     

  • 0 in reply to John Treubig
    TI__Expert 6470 points

    John,

    Since the gauge only broadcasts to addresses 0x12 (charger, and 0x14 (host), I don't know what to say about your data above. Seems like you can accomplish what you want by disabling the alarm broadcasts by setting the AM bit in SMB.BatteryMode( ). But, you will have to reset it at least once per minute to keep it from flipping off again.

    Doug

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

    AM: —

     

     

    Enables or disables AlarmWarning broadcasts to the host and Smart Battery Charger

    0 = Enable

     

    AlarmWarning broadcast to host and Smart Battery Charger by setting the [BCAST]  bit in Operation Cfg B

    (default). The bq20z90/bq20z95 sends the AlarmWarning messages to the SMBus Host and the Smart Battery Charger any time an

    alarm condition is detected

    1 = Disable

     

    AlarmWarning broadcast to host and Smart BatteryCharger. The bq20z90/bq20z95 does not master the SMBus, and AlarmWarning

    messages are not sent to the SMBus Host and the Smart Battery Charger for a period of no more than 65 seconds and no less than 45 seconds.

    [AM] is automatically cleared by the bq20z90/bq20z95 60 seconds after being set to 1, independent of the [BCAST] bit.

    Related Variables:

    DF:Configuration:Registers(64):Operation Cfg B(2)[BCAST]

    Note:

     

     

    The system, as a minimum, is required to poll the Smart Battery Charger every 10

    seconds if the

     

    [AM]  flag is set.

  • 0 in reply to Doug Williams4811
    Prodigy 220 points

    Doug,

     

    Thanks for copying part of the Technical reference for the bq20z95 for me.  Once I looked closely at it I found I had totally reversed the bit order of the BatteryMode().  Additionally, I was unaware of the requirement to poll the Smart Battery Charger every 10 seconds.

    Doug Williams said:

    The system, as a minimum, is required to poll the Smart Battery Charger every 10 seconds if the[AM]  flag is set.

     

    Additionally, I checked the SMBus spec for the addressing, and it appears the format for specifying the addresses is sudo Octal, even though all TI documentation references 0x notation as though it were HEX.  If this is true, both you and I are referencing the same addresses as 0xB and 013 are the battery.   (Since the trace that follows shows the AM bit invoked and the gauge no longer alarms, I think this is the case).

     

     

    You will see that the trace below does show the battery gauge suspending sending the AlarmWarnings (bq20z95).

     

    Now my only difficulty is with another battery that is using a bq2084.  The bq2084 documentation shows that the BatteryMode() command should work for it too.  For some reason (show below) it is not.  I have also contacted the battery manufacturer to see if they know anything.  From the IC marking, it is a bq2084DBT/86KG4/DK8K [I used slashes to indicate new lines].   Any additional insight you can provide will be helpful.