The new Telegea Smartbox hardware has successfully passed functional testing and is getting ready for a first production batch. Time to take a closer look at what the board offers in terms of interfaces and functionality.

Here is a picture of the fully assembled board with all modules mounted. The brain of the board is the Raspberry Pi compute module which is hidden underneath the display. The PCB is 3x credit card size. It fits a standard 9 units DIN rail mounting enclosure but also a wall mount case is planned. The yellow boxes show the soldered interface connectors, the red boxes indicate the optional hardware modules which will only be plugged in if needed for a specific application.



Network connectivity

There is an Ethernet connector for wired network connection or an optional Wifi module.

Sensor connectors

There are 2 sensor connectors for connecting external temperature sensors (Dallas 1-wire sensors) and temperature/humidity sensors (DHT22 and SHT21). The board has also its own SHT21 sensor mounted.

When mounted, the optional XRF radio transceiver module additionally gives access to a wide range of WirelessThings sensors.

Actuator outputs

There are four relays mounted on the board which can control a fan coil (low, medium, high fan speed) and a boiler or motorized valve via on/off switch.

Power input

The integrated power supply allows for easy installation by connecting directly the mains power to the board without an external power adapter. However also a 5V input is provided.

Bus connectivity

There is an RS-485 serial port for connecting standard industrial devices which communicate over the widely used Modbus RTU protocol.

USB connections

There is a host USB port which allows to expand the system by any USB compatible external device. Also a device USB port is provided which is mainly used for the Compute Module flash programming.

Digital inputs/outputs

There are a number of input/output connectors to handle pulse counters (like energy meters, flow meters), status signals (e.g. “open”, “closed”) and more.

Touch display

This is optional. Both a resistive and capacitive touch screen can be plugged in if it is needed for a specific application like the smart thermostat.

And here is another close look at the board with two external sensors connected.


We would like to hear from you and get some feedback on the design of this new Smartbox PCB. Is there another interface you would like to see ? What about the form factor ? Any other suggestions ? Please leave your comments below. We’d greatly appreciate it.

4 comments on “New Smartbox Identity Kit

  • I think this project looks fantastic!  Have you gotten to a point that you’ve considered testers or making any sort of kit available to the public?  It sounds like you’re not ready for “production” yet, but I’m ready to give it a shot!  I love the cleanliness of the system, and has a plethora of features that seem to allow for great customization.  Great project!

    • Thanks for your feedback. Unfortunately there haven’t been any updates here for some time but the project is alive. We have implemented some minor improvements of the PCB to overcome some issues that were discovered during prototype testing. We are currently analysing the effort to integrate also the M-Bus interface which is widely used for utility meters (water, gas, energy). And we have to arrange for compliance testing (EMC, CE). So hopefully it will be possible to produce the first revision of the Smartbox hardware soon. Then it should also be available for testers.

  • The drive capability of both the pseudo-I2C bus for the DHT22 and the Dallas 1-wire bus for additional sensors does not permit long-range connections to sensors. Have you made provision for that? also, have you transplanted the Pi to the board or have you designed your own SOC control section? If it is a re-design, which ARM processor and version of Operating System have you settled on? Overall – I think that you have a good design and are to be commended for maintaining a commitment to open source firmware.  (Note: Please send a response to my email address as I don’t often get to this page).

  • Maximum cable length for SHT21 (I2C) and DHT22 (proprietary 1-wire) sensors is just about 2 m. For longer distances we use (and recommend) Modbus connection. But sensors with Modbus interface are considerable more expensive, of course. The Dallas 1-wire bus for temperature sensors works fine with long cables. We have successfully tested 10 sensors on a single bus with the last sensor about 15m from the SmartHub. We might integrate an I2C to Dallas 1-wire bridge in a future revision of the board to reach even longer distances and be able to use more sensor types.

    As for the processor core of our board, we use the first generation Raspberry Pi Compute Module. All the software running on a standard RPi is also running on the SmartHub. The complete SmartHub OS with our customizations is available on GitHub and will always be open source. We are convinced that this is a better way of doing things and hope that other developers join this project.

    By the way, production of the latest revision of the SmartHub is starting these days and we hope to show the first pictures here in a few weeks.

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