MultiNav Pro+ BLE module - what's the actual current draw during active TX?

@Jason Griffin good question, and honestly one that comes up a lot when people start pushing the module into real power-constrained deployments. I don't have a precise published TX current figure to hand you right now — that level of detail isn't in the public docs yet, and I'd rather tell you that than give you a number that sends your power budget sideways.

 

What I'd recommend in the meantime is just measuring it directly at the bench before you lock the enclosure — throw a current probe or a low-side shunt on the rail during a TX burst and scope the peak. With the supercap system's low ESR you'll actually get a pretty clean picture of what the voltage dip looks like under that transient load, which is more useful for your sizing calc than a datasheet number anyway since you'll see the real behavior with your specific cap sizing and trace impedance.

 

On the TX power control question — that's definitely worth flagging directly to Moamen through the Dev Hub or the Command Center, because if the STM32WB07 core supports adjustable TX power levels via the firmware (and it likely does at the radio layer), exposing that as a configurable parameter would be genuinely useful for exactly this kind of use case. Running at max output for a 200m link is a real waste and it's the kind of firmware feature that would get a lot of traction from the community.

 

For the GNSS + BLE simultaneous draw situation, I'd design around worst-case both-active peak and then let the actual bench measurement tell you whether you need extra cap headroom or if duty cycling the GNSS fixes is enough to keep the rail stable.

Ran into the same gap in the docs when I was doing a similar build - ended up just scoping it directly on the bench and saw peaks around 180-220mA during active TX at full power, but honestly that can vary a bit depending on your antenna match and what BLE PHY mode you're running. Worth throwing a 0.1ohm shunt in series and logging it yourself before you finalize the cap sizing, especially if you're doing burst transmissions where the inrush matters more than steady-state. Tag @Mira_K in here too, she did a whole teardown/power profile on the MultiNav a few months back that might have more detail.

Seconding the shunt resistor approach - that's exactly how I nailed down my power budget on a similar supercap build, and honestly the variance Jason mentioned is real, I saw closer to 240mA peaks on mine when the PHY dropped back to 1M mode during a noisy environment test. Definitely dig up Mira's teardown if you can find it, think she posted it in the project showcase section, had some really solid cap sizing math in there too.

Yeah the variance between PHY modes is the killer here - I actually logged some of this a while back and the jump from 2M to 1M PHY alone was pushing an extra 30-40mA on my unit, so if you're sizing caps for worst case you really do want to capture that scenario specifically. Mira's teardown is def worth finding, but either way I'd size in at least 20% headroom over whatever peaks you measure because the supercap's internal resistance is gonna cause more voltage sag than you expect during those burst cycles.