EasySkyMesh Power Saving 14.1: Heltec V4.3 at 5.5 mA

EasySkyMesh just dropped Power Saving 14.1, and the headline number is worth paying attention to: 5.5 mA idle on the Heltec V4.3. That’s an always-on repeater, actively listening for packets and ready to forward, pulling 5.5 mA.

Built on top of MeshCore v1.14.1, this release adds Heltec V4.3 support, granular control over the Front End Module LNA on 1W boards, a new powerlog CLI for crash debugging, and meaningful power reductions across companion firmware.

We haven’t flashed 14.1 to our production repeaters yet. Numbers below come from the EasySkyMesh release notes and board-specific testing by Wireless Rocks (credited inline). When we have real-world data from our own nodes, we’ll update this post.

Heltec V4.3 Support

The Heltec V4.3 is now fully supported, with automatic detection between V4.2 and V4.3 hardware revisions. No manual configuration needed. The firmware figures out which board it’s running on and adjusts.

What makes the V4.3 interesting is the combination of 1W output power with controllable FEM hardware. That FEM control is what unlocks the power savings below.

FEM LNA Control: The Big Power Lever

This is the most operationally significant addition in the release. On 1W boards like the Heltec V4.3, the Front End Module includes an external Low Noise Amplifier that improves receive sensitivity. At a cost of up to 7.8 mA of additional current draw.

EasySkyMesh 14.1 gives you direct CLI control over this:

set radio.fem.rxgain off    # Disable FEM LNA (saves up to 7.8 mA)
set radio.fem.rxgain on     # Enable FEM LNA (better RX sensitivity)
get radio.fem.rxgain        # Check current state

This is separate from the chip-level LNA inside the SX1262, which you control with:

set radio.rxgain off        # Disable chip LNA (saves ~0.5 mA)
set radio.rxgain on         # Enable chip LNA

What this means in practice

Configuration	Heltec V4.3 Idle Current
FEM on, chip LNA on	~13 mA
FEM off, chip LNA on	~5.8 mA
FEM off, chip LNA off	~5.5 mA

That’s a 2.4x reduction just by toggling two settings. The tradeoff is receive sensitivity. You’re giving up range on the RX side. For many repeater deployments, especially dense urban meshes or solar-powered nodes where the power budget matters more than maximum receive range, that tradeoff is well worth it. Credit to Wireless Rocks for V4.3 power testing and validation.

Note: the Heltec V4.2 returns “Not supported” for radio.fem.rxgain because V4.2 hardware doesn’t expose FEM control. The Heltec T090 is also excluded from FEM LNA control in this release.

Power Savings Across the Board

Current idle draw with power saving enabled:

Board	Repeater / Room Server	Companion
RAK4631 (nRF52)	5.0 mA	5.8 mA
Heltec V3 (ESP32)	10 mA	Not yet released
Heltec V4.2	13 mA	Not yet released
Heltec V4.3 (FEM off)	5.5 mA	Not yet released

nRF52 companion firmware, available now

Companion firmware on nRF52 now runs power saving by default. No CLI toggle needed. That’s a drop from 9 mA down to 5.8 mA out of the box. Binaries are available for these boards:

RAK4631
RAK3401
RAK WisMesh Tag
Heltec T114
LilyGo T-Echo
T1000-E
Seeed WioTracker L1
Xiao nRF52

ESP32 companion firmware, pending

The release notes originally targeted March 30 for ESP32 companion binaries (Heltec V3 and V4), but as of this writing those binaries haven’t been uploaded yet. Check the release page for updates. They could land any day.

Repeaters and room servers use the CLI to enable power saving:

powersaving on     # Enable power saving mode
powersaving off    # Disable
powersaving        # Check current state

PowerLog: Debug Why Your Node Reset

The new powerlog CLI command shows you:

Last reset reason. Was it a software fault, watchdog timeout, or brownout?
Last shutdown reason (nRF52 only). What triggered the shutdown.
Last boot voltage (nRF52 only). Battery voltage at the moment the node came back up.

When a remote node resets and you don’t know why, powerlog gives you the forensics. A boot voltage of 2.9V tells you the battery sagged. A watchdog reset points to a firmware hang. A brownout tells you your power supply can’t handle transmit current spikes.

Sensor CLI and I2C Improvements

The sensor CLI command now lists I2C and GPS serial pin assignments for your board. Quick sanity check when wiring up BME280, BME680, or BMP280 sensors. No more hunting through datasheets to confirm which pins the firmware expects.

Other sensor improvements:

Automatic I2C address selection for BME280, BME680, and BMP280. The firmware probes both 0x76 and 0x77 and uses whichever responds.
I2C probe on startup so only connected sensors are initialized, reducing unnecessary bus traffic and power draw.
New board support for Xiao S3 (non-Wio) and Wio SX1262 with I2C on D6/D7.

ESP32 Date Persistence Across Resets

Previously, an ESP32 crash, watchdog reset, or brownout would lose the system date. Now the date is preserved across these events. This matters for logging and telemetry. When you’re reviewing sensor data after a node hiccup, timestamps that say “January 1, 1970” are useless. Accurate timestamps after a reset mean your data stays interpretable.

How to Flash

Upgrade existing devices. Download upgrade.bin from the release.

Fresh installs. Download freshInstall-merged.bin.

Detailed flashing instructions: Flash Custom Firmware Guide.

Sensor wiring guide: Add Sensors to Repeaters.

Source code: PowerSaving-v14.1 branch.

Download EasySkyMesh Power Saving 14.1.

Should You Update

If you’re on any previous EasySkyMesh release, yes. The FEM LNA control alone is worth it for anyone on 1W hardware. You now have a real knob for trading RX sensitivity against power draw. Companion power savings enabled by default on nRF52 means less configuration on fresh installs. And powerlog will pay for itself the first time a remote node acts up and you need to know why.

Upgrade your easy-to-access devices first. That’s good advice from the EasySkyMesh team and it applies doubly here. Test the new power saving behavior on nodes you can reach before rolling it out to your rooftop repeaters.

Support the Developer

Power optimization, board-specific tuning, sensor integration, and release packaging. This is the work that makes MeshCore deployable in the field. If EasySkyMesh is running your backbone:

PayPal: paypal.me/iotthinks
GitHub Sponsors: github.com/sponsors/IoTThinks

This post covers community firmware built on MeshCore. NodakMesh isn’t affiliated with EasySkyMesh or IoTThinks. We highlight ecosystem work that makes mesh networking more practical for everyone. For more on the base firmware this release builds on, see our MeshCore v1.14.1 release post.