The manufactured client node has been inserted into the enclosure containing an European mains socket (female) on one side and an European mains plug (male) on the other side, forming a man-in-the-middle adaptor, that can be non-invasively put between wall socket and an appliance. The result can be observed in figure \ref{f:project_inside}.
\caption{The view into the client node's enclosure, before the final assembly}\label{f:project_inside}
\end{figure}
\subsection{Discovered problems}
After a few test runs performed on an assembled client node, the first problem became obvious: the node's application processor (contained inside of the ESP-12E module) starts erratically, when the node is plugged into socket. Investigations of the supply voltage under the oscilloscope shows no difference in voltage surges during the boot-up, either if the processor starts or not, suggesting a firmware problem too. The first 220ms of power line inspection can be seen in the figure \ref{f:oscilloscope}. However, this problem does not occur, when the processor is powered from external source via J3, but otherwise makes the node unreliable to use.
\caption{The power line of the ESP-12E inspected during the boot-up by the oscilloscope - it looks the same either if the processors boots, or it doesn't, suggesting the possible occurence of the ESP8266 firmware problem}\label{f:oscilloscope}
\end{figure}
Ignoring the boot-up problem, the client node is sort of working as indented, apart from one huge problem with the MAX78615 \gls{ic}, that was not apparent during the design stage: the \gls{spi} protocol only allows for 6 bit long memory addressing, enabling only the first 64 words of the memory to be accessed, leaving the 104 words out of 186 completely inaccessible. As a result, from the required data, only RMS Voltage and RMS Current can be obtained. All the data depending on phase shift, namely real power, reactive power and power factor are not accessible.
The \gls{spi} limitation obviously cripples the node's functionality. The protocol was chosen, because the data-sheet for the MAX78615 suggested it as the only way to obtain the instantaneous measurements, as discussed back in the sub-chapter \ref{ss:schematic_pcb}. Although the instantaneous measurements are not required, there was no reason to not enable this feature in the design stage. The fact, that such a limitation exists was observed too late.
Requesting help from the technical support of the \gls{ic} manufacturer, the Maxim Integrated, did not help resolve or at least minimize the damage. They responded, that they are no longer supporting the part in question, because whole power measurement department was sold to another manufacturer based in China, Silergy Corp in March 2016.
There are multiple, rather cosmetic issues, that does not affect the functionality of the board, but are imposing small physical troubles. They include the following:
\begin{itemize}
\item The J3 header is wrong pitch (2mm instead of 2,54mm)
\item The mounting holes are too small diameter
\item The longer side of the board is 1mm wider than desired, it doesn't fit easily into the enclosure
