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Hitting a new low-power record with the esp32c3

Tags ESP32  Low Power  RiscV 

When looking up some information I blogged about in the past, I realized I haven’t posted any updates in ages. A while back I switched to esp32s2 and got some nice result out of this single core chip. However espressif in there wisdom decided to stop producing the esp32s2-wroom and marking it NRND. This must be their shortest lived SoM. The did release the esp32c3, this is another single core chip, with a RiscV running at 160MHz. I think it is a step down from the esp32s2; less hardware modules (f.e. One that I used for 1 wire protocol), no ulp, bluetooth (that I don’t need), needs more external components and less pins on the wroom module.

ESP32 C3

On the positive side, its been very reliable, allows for some tiny pcb design and get low deep-sleep consumption. On my test-print it goes to ~7µA usage in idle (this includes with a 2MΩ divider for measuring battery voltage). This together with a good espnow implementation makes it extremely low power. For a quick every 2 minutes ‘ping I am here’, I get a ~94µAh usage.

Usage long

But if we zoom in, we do see a fairly high spike, making battery selection tricky:

Usage short

Given I switched to LifePO4 batteries, even with the lower capacity, I still get years battery lifetime.

To use the module I’ve designed a little PCB, that works for both LifePO4 or LI-ION batteries (I do undervoltage in software for LifePO4 or use protected cells for LI-ION):


Or soldered (v0.2):


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