The current build of Shoto HDK comes without R21 populated on the board, this means that charging of the battery via USB is disabled if your battery does not have a thermistor installed.

A battery without a thermistor between the negative terminal on the battery and the thermistor pin on the Shoto HDK must be removed in order to charge it externally.

There is, however, a way to "install" a thermistor, pictured below. The recommended thermistor type is a 103AT NTC 10kOhm thermistor, pictured below is digikey P/N: 490-7171-ND secured to the aluminum exterior with kapton tape.

With a battery and thermistor installed, the USB connector is typically in battery charge mode until a safety timer is triggered; the "identify controller" functionality will still work during charging when connected to SteamVR. The Shoto HDK will show a Red/Yellow to indicate battery charging mode.

It is best to first turn on the Shoto HDK using the on-board button (by holding it down for three seconds), then connecting via USB to charge the battery, so that the status LED shows a solid green.


If operating via USB without a battery, the fpgawrite commands below enable all sensors to begin reading normally and must be completed in lighthouse_console every time the device is unplugged.

"fpgawrite 0x22 0x00"
"fpgawrite 0x22 0x10F"

Suggested Battery Suppliers:

If you are designing a tracked object and would like to integrate a thermistor into the battery for the product, Honcell produces the battery mentioned in the powerpoint slides included in SteamVR HDK.

More information on batteries available from Honcell:

PK Cell may also be able to provide samples of batteries for your product with a minumum order quantity of 5000 pieces:
contact e-mail:

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