Jake Wachlin's MetaShunt V2 Boosts Performance and Adds a Standalone Power Monitoring Mode
The 10,000,000:1-range power measurement tool just got better — and there's new software to make it even more useful, too.
Maker Jake Wachlin has been in touch to alert us that he's revisiting his MetaShunt high dynamic range current measurement tool, unveiled a little over a year ago, with significantly boosted performance — and the new version is called, sensibly enough, MetaShunt V2.
"I recently launched a V2 of MetaShunt, which improves performance significantly. Of more interest to your readers, though, I added two features that I think are really useful," Wachlin tells us. "First, MetaShunt can now measure and accumulate 'current × time' consumption data (think milliamp-hour) and display it on an LCD display. With this feature, MetaShunt is now great both for optimizing a system and checking out and verifying its total energy consumption over long periods of time, since it only needs power over USB to do this (no computer is required)."
"Second," Wachlin continues, "I built software tools to allow easy comparisons between my power estimation software and MetaShunt data. This is super helpful for verifying to design specifications and can also be used during the optimization process to compare how changes in firmware are effecting power consumption."
Wachlin unveiled the original MetaShunt back in February last year, as a device for measuring current in ultra-low-power devices — with a 10,000,000:1 range, from 50nA all the way up to 500mA, achieved by having the device engage multiple shunt resistors as-required. "By measuring current rapidly over time," Wachlin explained at the time, "the total energy use during a given portion of your code can be determined. MetaShunt acts as a virtual ground for your system, so that you can use your battery. Or, MetaShunt can provide 3.3V or 5V to the system under test if desired."
The ability to drill down is handy, of course, but sometimes you need to look at the bigger picture — which is where MetaShunt V2's ability to act as a long-term energy usage monitor comes in. An on-board display shows total power-on time and total current usage over that time, in nano-, micro-, or millamp-hours. "These calculations are done with the same high precision and fast update rates that MetaShunt V2 uses when streaming measurement data to your computer," Wachlin promises.
Other improvements in the second-generation release include software tools that deliver easy comparison with estimates generated by Wachlin's energy modeling tool, easier calibration, a switch to spring-pin terminals, and performance enhancements including a doubling of the internal sample rate to over 700kHz, a 14-bit analog to digital converter (ADC) instead of 12-bit, burst measurements up to five times faster than before, and a 20 per cent boost to continuous data output rate.
The MetaShunt V2 is available to order on Wachlin's Tindie store now at $299, or without the on-board LCD at $249; the new software tools are available on GitHub under the permissive MIT license. Additional information is available on Hackaday.io.