Problem
A researcher was using a common oceanographic data collection unit, but the manufacturer did not provide enough data storage memory to allow the device to be used in long duration projects. The researcher asked AO to examine the unit to determine if the internal memory could be expanded.
Solution
We reverse engineered the circuit and determined that it would be relatively easy to install a memory expansion board that would provide several times as much memory as the original unit. AO designed a prototype and it proved effective using normal device programming methods.
We then produced a memory expansion board that included its own battery backup lithium cell to protect data in the static RAM even if the unit's main battery failed. One provision of the backup battery circuit was the ability to electrically disconnect the backup battery after the unit was programmed to conserve battery life. The disconnect circuit automatically switched on the backup battery after the first data write operation to the memory. An interesting feature of the disconnect circuit was that it was powered from the backup battery with an extremely low 50 nanoamps power consumption.
Results
The relatively inexpensive memory expansion board worked as expected and allowed the researcher to use the expensive data loggers for long duration projects.