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User Documentation


Press any button to start the menu system. There are only a few features available here since we rely on web browser access to control and setup most functions.

Network Setup

Internal web page: Wifi

Configure and personalize

Internal web page: Display

Display Preferences

Personalization of how the values are displayed is done here.

Other Preferences

Internal web page: Preferences

Firmware Management

Internal web page: Firmware

Old releases and downloadable firmware files are available here.

User API

Use with Opendime

Connect any Opendime to the USB port on the left side. The display will change to indicated what state the device is in: Factory Fresh, Sealed or Unsealed. A full and complete verification of the Opendime’s bitcoin signatures and authenticity certificate is performed before the QR code is shown. This can take up to 10 seconds. Once that’s done, you can select “Show Balance” on the top button, and the address of the Opendime will be used to look up any UTXO on the blockchain.

Fiat value of the balance will also be displayed. The exchange-rate and specific fiat currency is configurable under Preferences in web interface. The default is USD based on average exchange rate.

If your Opendime is unsealed, an additional menu item is visible: Reveal Private Key When pressed, another QR code is shown, which reveals the private key to be swept to claim the funds on the Opendime.

Opendime Notes

Privacy and Security


Your Opendime balance is never sent to our server, however, we do use to look up balance (UTXO’s) for the Opendime. This reveals your IP address to them, and implies you hold (or held) that specific Opendime. For this reason, the balance is not automatically fetched and you must press the button. All verification of the Opendime is offline and does not interact with the network, until and unless that button is pressed.

You can change the URL used for balance checking to another service, however they must implement the same Explora protocol. Future firmware versions may support more alternatives.

The balance amount is not shared with Coinkite’s backend server, instead the multiplication of exchange rate and BTC quantity is done inside the BLOCKCLOCK.

Broadcasting Bitcoin Transactions

You can choose to broadcast your signed Bitcoin transactions using the BLOCKCLOCK mini.

For example, the transaction can come directly from the MicroSD Card which the COLDCARD saved the transaction onto when it signed it. This means the signed transaction has never touched your desktop or mobile platform.

Again, can link your transaction and IP address. You can change the service used to broadcast to another provider on the Preferences page. The URL must accept hex-encoded transactions, and provide a JSON or text response. There are many public endpoints that can do this.

Normal Operation

The BLOCKCLOCK mini keeps a connection open to our backend server all the time. No settings or long-term information is stored there, so the privacy impact seems minor. It’s only used to get the values for display, perform searches for tag names and so on. Nothing about your holdings is revealed to us, aside from your great taste in Bitcoin hardware.

If you want to avoid even this disclosure, you can change the URL for the backend server, and/or leave it broken and only use the push API to update the display. If you operate this way, you might want to adjust your DHCP settings so the mini cannot reach outside your local network at all. For firmware updates, you can use SDCard to sneakernet the file.


The web interface on this product was not designed for the public Internet. It is meant to used on internal private networks like your home LAN. Do not put it outside the firewall.

There is no proper operating system on this product. It is an ESP32 chip running Micropython as an FreeRTOS task. The networking stack is another FreeRTOS task.


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