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Associate II
January 8, 2026
Solved

STWLC38 register addresses and saving

  • January 8, 2026
  • 1 reply
  • 174 views

Hi all,

I have a board designed using the STWLC38 as the Qi Rx. An ESP32 is the host controller using I2C to configure the STWLC38. The communication works OK and I can set and read various registers.

I have two questions on this configuration:

The STWLC38 datasheet lists the functions of all the various registers but doesn't list the addresses for many of them. Are these available elsewhere?

The STWLC38 is powered from the Qi coil so that I can only read/write when I have a successful pairing. How can I save my custom parameters to RRAM using I2C?

Thanks in advance.

Best answer by Didier HERROUIN

Dear NickA,

Only the useful registers are described in the datasheet, they are not described somewhere else.

If you want to save your custom parameters, you must supply the STWLC38 (with a 5V on Vout or on Vrect) when it is not a wireless charger. You can connect the GUI and save/write the configuration file.

In parallel, please open a case on st.com (https://www.st.com/content/st_com/en/support/support-home.html#), you ticket should be re-directed to me and I will be able to support you directly. 

1 reply

Didier HERROUIN
Didier HERROUINBest answer
Technical Moderator
January 9, 2026

Dear NickA,

Only the useful registers are described in the datasheet, they are not described somewhere else.

If you want to save your custom parameters, you must supply the STWLC38 (with a 5V on Vout or on Vrect) when it is not a wireless charger. You can connect the GUI and save/write the configuration file.

In parallel, please open a case on st.com (https://www.st.com/content/st_com/en/support/support-home.html#), you ticket should be re-directed to me and I will be able to support you directly. 

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