Making Of …

The production of the ECO Power boards for the first users and the exhibition at MakerFaire Hannover

The component list is exported from the “Eagle” PCB program, and compared with the component database, and then transferred to the machine using special software developed by the owner of the placement machine. Equipping the PCBs utilizing the machine is precise and fast.

The first batch of equipped boards is soldered in the reflow oven:

A self-constructed test adapter allows fast testing of all connections of the ECO Power board, thus it is quickly ensured that all GPIO pins and the analog connections work. In addition, the LoRa radio connection is tested, too. The modified Raspberry Pi in the background serves as a programmer for the installation of various test programs:

The fine SMD solder joints are checked under the stereo microscope and fixed, if necessary:

A programmable power supply unit is used to check whether the board works correctly via USB power supply and also via battery, and whether the power consumption is stable within the permitted range. The automatic power switchover from battery to USB and back is also tested:

The ADC reference voltage is measured on a per-board basis and permanently stored in the board. This ensures that battery voltage measurement and customer ADC applications deliver accurate results. The figure below shows that this ESP32 module has an ADC reference voltage of 1.074 volts instead of 1.100 volts. However, thanks to calibration the ADC measurements at the customer’s site work accurately:

The precise time is achieved by measuring and calibrating the temperature compensated oscillator of the clock (RTC). Calibration is performed with an atomic clock based 10 MHz frequency reference via a frequency counter. The necessary calibration is permanently stored in the board and provides a very precise time over years.

On battery operation, the complete solution including the enclosed sensor requires only 7 µA in the RadioShuttle “Node Offline” mode, which uses ESP32 “deepsleep”. Of course, we’ll check that very carefully:

One last independent inspection and the installation of the RadioShuttle software.

PS: Each pair of odd/even device numbers (e.g. 805/806) is programmed as a node and as a station (server). Thus, the sending/receiving of messages can be tested immediately – without installing any software. Put in the batteries and let’s get going!

For the first batch of boards we created wooden board holders with a laser cutter, so the boards have a firm base. Here is such a sample:

The board holders are great! Unfortunately, the laser needs one hour per run, then another good hour for gluing. In the initial phase, we include the component holders – the users will be surprised.

Not to forget: the complete hardware and software development as well as the production is “Made in Germany” (Hannover). The RadioShuttle Arduino boards (LongRa and ECO Power) were developed at Arduino Hannover, in the LoRa group. We wish you lots of success with the ESP32 ECO Power with LoRa board.