A versatile measuring instrument and data-logger built into a hand-held probe. The instrument has no controls or display instead using a Bluetooth Low Energy (BLE) connection to a smartphone or tablet app.
The SmartProbe will have the following components:
- A Cypress EZ-BLE PSoC module. This comprises a BLE radio, a 32-Bit ARM processor, programmable digital logic and highly configurable analog circuits.
- Li-ion Battery Power. A small rechargeable battery enables the probe to work without an external power supply and gives full galvanic isolation "for free".
- An FRAM memory chip for data-logging. This new memory technology is a fully non-volatile RAM avoiding the block writing and limited cycle lifetime of EEPROM.
- USB connection. As well as providing battery charging, this will allow for firmware loading and an alternative to BLE for reading the data-logger. It is not recommended for on-line measurements since it will break galvanic isolation.
The EZ-BLE module has all the active components needed for all but the most sophisticated instruments so the input components will be minimal and mostly passive. Initially it is planned to duplicate the functionality of a typical multimeter, but the probe will be easily adapted and extended to a range of more complex instruments such as LCR meters, transistor testers, frequency counters and even modest bandwidth oscilloscopes.
The app will allow the readings from multiple probes to be integrated to expand to a full data acquisition system.
I have a good deal of practical experience with the EZ-BLE PRoC module from which the PSoC module has been developed. It is very hobbyist friendly as the IDE is free and the USB programming/debugging adapter can be obtained as part of a starter kit for negligable cost. The analog and logic systems are configured using schematics and the BLE from a wizard which makes it easy to use custom BLE profiles rather than having to rely on standard ones provided by the SIG or the manufacturer.