USB-PD-CHG-EVM-01: writing issues in the BQ25798 registers

Mathis CEDRA

Part Number: USB-PD-CHG-EVM-01
Other Parts Discussed in Thread: BQ25798, BQSTUDIO

Hi,

I am currently testing a Powerbank USB-PD solution and I use the USB-PD-CHG-EVM-01 demo board seems to match my need. I would like to program the BQ25798 registers myself in order to select the battery protection values. However, it is not possible to write to registers, once the board is powered on, defaults are written and the write data is overwritten.

While browsing the other forums, it seems that this problem is related to the WD timer but it is impossible for me to enter the host mode despite following the instructions in the datasheet of BQ25798.

below the configuration of the map and the tools used:

Setup-up: with active JP2 jumper

config TPS25750D:
{"questionnaire":{"version":"7.0.3.13","answers":[0,2,3,0,0,null,1,null,1,null,0,12.6,2,0.4,0.76],"options":{},"configID":"0000","vendorID":"0000"}}

Capture BQstudio:

1. My problem really comes from the WD Timer?

2. Is it possible to provide me with the procedure for entering in host mode?

Thank you!

3 months ago

0 Christian Moyer 3 months ago

TI__Genius 12955 points

Hello Mathis,

What registers are you writing to?

You should be able to write to the BQ25798 directly, it could be possible that the USB-C PD controller is overwriting these register.

Mathis CEDRA said:
defaults are written and the write data is overwritten.

To clarify, if you write to a register and then click the read register button, your selected values are not saved?

Best Regards,

Christian.

0 Mathis CEDRA 3 months ago in reply to Christian Moyer

Prodigy 20 points

Hello Christian,

Christian Moyer said:
What registers are you writing to?

I would like to write in the following registers:

- VSYSMIN (REG_00)
- VBAT_LOWV (REG_08)
- TSHUTdown Temp (REG_16)
- TREG Temp (REG_16)
- ICHG (REG_03)

Christian Moyer said:
To clarify, if you write to a register and then click the read register button, your selected values are not saved?

Yes, I write to the registers and when I restart the board, the changes are not saved.

Best Regards,

Mathis

0 Christian Moyer 3 months ago in reply to Mathis CEDRA

TI__Genius 12955 points

Hello Mathis,

Mathis CEDRA said:
Yes, I write to the registers and when I restart the board, the changes are not saved.

So you perform a POR? Do all of the register get overwritten?

VSYSMIN (REG_00) and ICHG (REG_03) will reset on POR event, so they will need to be written every time the board is powered on.

Best Regards,

Christian.

0 Mathis CEDRA 3 months ago in reply to Christian Moyer

Prodigy 20 points

Hello Christian,

Christian Moyer said:
VSYSMIN (REG_00) and ICHG (REG_03) will reset on POR event, so they will need to be written every time the board is powered on.

Okay, I understand for registers VSYSMIN (REG_00) and ICHG (REG_03) are reset after the board is restarted.

Christian Moyer said:
So you perform a POR? Do all of the register get overwritten?

Yes, all the registers get overwritten. But, VBAT_LOWV (REG_08), TSHUTdown Temp (REG_16) and TREG Temp (REG_16) registers are controlled by Power-On-Reset ?

Every registers are controlled by POR ? Is it possible to disable POR ?

Best Regards,

Mathis

0 Christian Moyer 3 months ago in reply to Mathis CEDRA

TI__Genius 12955 points

Hello Mathis,

Mathis CEDRA said:
Yes, all the registers get overwritten. But, VBAT_LOWV (REG_08), TSHUTdown Temp (REG_16) and TREG Temp (REG_16) registers are controlled by Power-On-Reset ?

Yes, I just checked and they all have a default POR value.

Mathis CEDRA said:
Every registers are controlled by POR ? Is it possible to disable POR ?

No, this can not be disable. These values will have to be set each time the device is powered on.

Best Regards,

Christian.

0 Mathis CEDRA 3 months ago in reply to Christian Moyer

Prodigy 20 points

Hello Christian,

So, all registers from BQ25798 are controlled by POR ?

Best Regards,

Mathis

+1 Christian Moyer 3 months ago in reply to Mathis CEDRA

TI__Genius 12955 points

Hello Mathis,

Mathis CEDRA said:
So, all registers from BQ25798 are controlled by POR ?

Yes.

Best Regards,

Christian.

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USB-PD-CHG-EVM-01: writing issues in the BQ25798 registers