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Comment by levpopov | Hacker News Reader

I love RP2040 (especially how circuit designer and firmware dev friendly it is) and even tried building my own MCU with it[1]

However I don't quite see the Bluetooth use case - RP2040 is not really a low power chip, making it pretty hard to use for a battery-powered IoT application. You'd need a pretty giant battery pack to make it last a long time.

Nordic's nrf52 is an order of magnitude better for a typical "sleep-burst transmit-sleep" cycle, and can be suspended to <5uA current. Pico W is $6, Seeed has a $10 nrf52 MCU, or you could get a "just hook up USB and power" bare module for $5-6.

[1] https://twitter.com/levpopov/status/1623376630378008576

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nit: MCU is Micro Controller Unit, so for example rp2040 itself. What you mean is "board".

Completely right on the power consumption though. The NRF52 is also quite good at limiting power consumption while it's running and automatically disabling peripherals while not used (you typically do that with disabling clocks on other chips). It also has the sanest hardware registers I've seen (looks like they were actually designed with software in mind).

Yes, thanks for the correction! In DIY keyboard community a microcontroller breakout board is often referred to as MCU which makes things confusing.

There's also a fully open source Bluetooth stack for the Nordic chips (Apache nimBLE) compared to the non-commercial use only but with some vague and possibly not yet available exception for the RP2040 license of the BTstack used here. (This seems to have been enabled by the radio hardware being fully documented, which is very unusual for Bluetooth chips.)

It's possible to use the RP2040 in a low power way if you're specifically code it to do so, no? It should be able to consume as little as 1.3mA in sleep state, so if you had an application with a loop that did something like read a sensor and send out a bluetooth or wifi signal, then sleep for 15 minutes, I think a few AAA batteries could power it for months, no? https://raspberrypi.stackexchange.com/questions/124951/raspb...

I've got a bunch of ESP32's piggy-backing on USB chargers around the house doing BLE and wifi stuff. The things they're talking to are battery powered, but I want them plugged in to the mains. I could easily see myself using the Pico W in that job.

There are a lot of IOT applications that do rely on battery power. Regardless, this is nice for people whose MCU/embedded experience is limited to pre-existing firmwares and the Arduino ecosystem.

One use case would be a little desktop robot for an educational setting. The motors of a robot use orders of magnitude more power than the CPU so it needs big batteries anyway.

I can also imagine applications where the device has wall power but you want to connect to it with a phone. Like a piece of wall art you want to be able to turn on and off remotely.

RPi is too expensive to be an end-point IoT device too. But it is perfect to serve as a hub/base station. And this is where BT could be actually of use, for communication with cheaper end-point devices, for example.

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