Post Go back to editing

LTC6813 responding with 0xFF for everything

I'm using the LTC6813 on a custom built PCB, and have the reference Linduino software that I got from here running on an Arduino Uno.

The VREG bus is at 5.25V and then turns off after 2s if no command is received(as expected), however, the VREF1 and VREF2 pins are at 0V.

When the evaluation software requests information from the device of any sort, the SDO is held high (0xFF) during the data part of the transmission, but a PEC of 0x66, 0x4C is transmitted as well. 

When I send the command "1" to the Linduino software (Write and Read Configuration: 1), I get this as the output - 

Written Configuration:
CFGA IC 1, 0xE4, 0x0D, 0x28, 0xA0, 0x01, 0x00, Calculated PEC: 0xAD, 0x6A
CFGB IC 1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, Calculated PEC: 0xC2, 0x12

Received Configuration
CFGA IC 1, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, Received PEC: 0x66, 0x4C
CFGB IC 1, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, Received PEC: 0x66, 0x4C

Reading cell voltages in a loop (command 11) gives me -

Cells, 6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,6.5535,

I am unsure what is going on since obviously the chip is responding to commands with messages that have a valid PEC value. 

Thanks in advance, I'm happy to provide any more information that you'd like, including schematics of the board to find any hardware issues, if there are any. 

Chai

Parents
  • Hello Chai - 

    You are missing a step. You have configured the device and are reading a results register, but before you read the register you need to tell the LTC6813 what you want to measure - and initiate a measurement - by sending an ADCV command. So, the sequence looks like this: 

    1.  WRCFGA (Write Config)

    2. RDCFGA ( Read Config )

    3.  ADCV (starts measurement- you should see the supply current on Vreg bump up to about 15 mA, and the Vref1 should go to approximately 3.15 V, and Vref2 will go to about 3.0V) 

    4.  RDCVA, RDCVB, etc. (read results of measurement) 

    Regards, 

    John Smith

Reply
  • Hello Chai - 

    You are missing a step. You have configured the device and are reading a results register, but before you read the register you need to tell the LTC6813 what you want to measure - and initiate a measurement - by sending an ADCV command. So, the sequence looks like this: 

    1.  WRCFGA (Write Config)

    2. RDCFGA ( Read Config )

    3.  ADCV (starts measurement- you should see the supply current on Vreg bump up to about 15 mA, and the Vref1 should go to approximately 3.15 V, and Vref2 will go to about 3.0V) 

    4.  RDCVA, RDCVB, etc. (read results of measurement) 

    Regards, 

    John Smith

Children
  • Hi, 

    I apologize for the delayed response, I had some hardware issues with the design that I had to contend with first.

    On step 3 of the above sequence, where the VREFx voltages are supposed to come up, nothing happens. The VREF voltages stay at 0V and the ADC measured values are completely arbitrary which is likely a result of an incorrect VREF voltage. I am unsure what might be causing this issue

    Thanks

    Chai

  • Hi,

    I have problem where I am unable to write to the CFGR register itself. I am setting DTEN bit in CFGR0. I am able to write 0xFC 0x00....6 BITS and 2 bits of the correct PEC(verified using the MULTICELL MONITOR GUI). But when I read from the CFGR, I always get 0Xd8 0X00...6 BITS 0x92 0x18 WHICH is the default value. This means that write to CFGR is unsuccessful. i am stuck at this point and unable to proceed further