# Measuring Current with Matt Liberty

- Show: [The Amp Hour](https://hardwarepodcasts.com/podcast/the-amp-hour)
- Published: 2021-01-25
- Length: 1h 20m
- Episode: 527
- Page: https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty
- Listen: https://theamphour.com/527-measuring-current-with-matt-liberty/

## Summary

Matt Liberty, creator of Joulescope, explains the engineering challenges of measuring high dynamic range currents in low-power IoT devices, specifically addressing the difficulty of switching between milliamp active states and microamp sleep states. He details how Joulescope uses a shunt ammeter design with seamless auto-ranging to minimize burden voltage, preventing device brownouts, and leverages Lattice iCE40 FPGAs for precise, sub-microsecond switching. The conversation covers practical applications for optimizing firmware power profiles, debugging leakage currents from components like bypass capacitors, and managing the supply chain and manufacturing processes for a small-batch hardware startup.

## Chapters

- [0:00](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=0) Introduction: Matt Liberty and the Joulescope
- [0:00](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=0) The Challenge of High Dynamic Range Current Measurement
- [0:00](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=0) Joulescope Hardware Design: Shunt Resistors and Burden Voltage
- [10:44](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=644) Measuring IoT Power Cycles: Cellular Modems and nRF52
- [10:46](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=646) Using GPIO Toggles and Waveform Views for Power Profiling
- [21:38](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=1298) Resolution vs. Accuracy and Low Power Design Pitfalls
- [21:38](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=1298) Debugging Leakage: Back-powering, I2C, and Flux Residue
- [41:25](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=2485) Building the Company: Consulting to Product Transition
- [41:27](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=2487) Supply Chain, Manufacturing Partners, and Calibration
- [1:04:35](https://hardwarepodcasts.com/podcast/the-amp-hour/2021-01-25-measuring-current-with-matt-liberty#t=3875) FPGA Implementation and Future Product Roadmap

## Topics

- [Batteries & low-power design](https://hardwarepodcasts.com/topic/batteries-and-low-power)
- [PCB design & layout](https://hardwarepodcasts.com/topic/pcb-design)
- [Microcontrollers & dev platforms](https://hardwarepodcasts.com/topic/microcontrollers-and-platforms)
- [Chips, FPGAs & semiconductors](https://hardwarepodcasts.com/topic/chips-and-fpgas)
- [Manufacturing partners & offshoring](https://hardwarepodcasts.com/topic/manufacturing-partners)
- [Starting a product company](https://hardwarepodcasts.com/topic/starting-a-company)

## Most relevant to

early-stage companies

## Mentioned

- Joulescope (product)
- Keithley (company)
- nRF52 (chip)
- Lattice iCE40 (chip)
- Keysight (company)
- Nordic (company)
- Power Profiler Kit 2 (product)
- Salae Logic (product)
- DigiKey (company)

## Related episodes from other shows

- [278: Bricks' Batteries Last Forever (Repeat)](https://hardwarepodcasts.com/podcast/embedded-fm/2022-02-11-278-bricks-batteries-last-forever-repeat) (Embedded.fm)
- [278: Bricks' Batteries Last Forever](https://hardwarepodcasts.com/podcast/embedded-fm/2019-02-15-278-bricks-batteries-last-forever) (Embedded.fm)
- [The Spark Gap - Episode 42](https://hardwarepodcasts.com/podcast/the-spark-gap/2015-10-21-the-spark-gap-episode-42) (The Spark Gap)
- [The Spark Gap - Episode 44](https://hardwarepodcasts.com/podcast/the-spark-gap/2015-12-25-the-spark-gap-episode-44) (The Spark Gap)
- [Microchip Technology's Patrick Kennedy | Designing IoT Products to Scale](https://hardwarepodcasts.com/podcast/iot-for-all-podcast/2020-07-13-microchip-technologys-patrick-kennedy-designing-iot-products-to-scale) (IoT For All Podcast)

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