If you’re like me and constantly seeking ways to optimize power consumption in low-power embedded systems, here are some insights you might find valuable!
Last week I got my XIAO nRF52840, and my first goal was to measure it’s energy consumption while this tiny board executed a simple operation: wake-up, run a blink sequence, and go back sleep. Here’s how I set it up using the Otii Ace Pro.
- Connected the Otii Ace Pro to my computer via USB, and wired up my device under test (DUT) with banana connectors—positive and negative terminals connected to the battery leads of the node.
- Opened the Otii Desktop App, added the Otii Ace Pro under the Control panel, and set the supply voltage. In my case, I set 3.3 V.
- Choose the channel I was looking to measure (current, voltage, power) so I could view everything in real time as the board went through its cycle.
Once everything was wired up and setup on the app, as shown above, I hit the recording button, turn on the power supply and boom! Here’s what I quickly found:
- Active Mode: 1.33 mA (not bad for an active sensor)
- Deep Sleep Mode: 2.14 µA (even better than expected!)
Nevertheless, it is never the same to power and measure the device by itself, versus powering and measuring with the expansion board.
So, since Otii allows me to compare all the results side by side, why not look at this difference? After syncing the measurements and analyze them I found the following:
Getting as result:
- Active Mode: 2.33 mA
- Deep Sleep Mode: 968 µA
While the difference in power consumption might seem small at first, it becomes significant when we calculate the device’s battery life using a 220mAh battery with a 1-hour sleep cycle. The XIAO nRF52840 on its own would last 3.1 years on that battery. However, when powered up using the expansion module, the battery life drops dramatically to just 9.4 days. Now that’s a huge difference!
If you’d like to dive deeper into these measurements, you can download the project here and open it in the Otii Desktop App–you can download it right here.
PJ 