[exmadscientist]

Nordic is not really that cheap if you just want a Cortex-M4. You buy Nordic parts for their radios.

If you just want processing power, GigaDevices has an M4 at less than $1 last I checked. Unfortunately, it wouldn't work for the design we were working on as the standby power consumption wasn't great.

[AlotOfReading]

If you want bargain basement processors with connectivity, Qualcomm is still selling many of the old CSR chips. The low end chips went for <$0.50 in volume and the power consumption was often barely worth measuring. We used to chuck them into products every time every time I lost an argument with the hardware team about whether 10-15 cents of BOM cost is worth 3 months of painful bringup.

[coupdejarnac]

Are you using fcc approved modules with the csr chips or the bare chips? I'd be interested in a really cheap bluetooth capable microcontroller. I plan to use the nrf52805 for my next product due to the low cost.

[AlotOfReading]

Sorry if that came across as an endorsement. I'd go with the nordic modules instead because the documentation and support will be much better. The development costs of weird, cheap wireless chips isn't worth chasing marginal BOM optimizations. Just don't go to the other extreme and spend $40 on an Intel SoC for your wireless thermometer like I've seen others do.

I haven't worked with CSR modules since I left that job around 2017, but the latest vendor toolchains for some chips were still on GCC 3 (~2005) at that time. We were taking bare reels and doing certification ourselves if it matters though.

[monocasa]

I don't think they wanted an M4 per se, but instead wanted a bluetooth radio to save on the cost of a screen. The Nordic chip just happens to be based around an M4.

[qbasic_forever]

IIRC Nordic has a M0 version with bluetooth radio--the BBC micro:bit and a few other maker boards used it. But perhaps it's not really available in cheap quantities anymore and a way overpowered M4 is what they got.

[monocasa]

Yeah, those are the nrf51x line, this is the nrf52x line. It seems from the outside at least that Nordic is pushing the nrf52x hard even in price conscious designs. Even the micro::bit was respun for a v2 with a nrf52x also (including it's M4). Albeit I don't have much direct data on that.

[floatboth]

Yes, the 51 is really old by now. The 52 line extends down as far as the tiny nRF52805.

The 51822 is not nearly as fun to work with as the 52s, e.g. current Apache Mynewt with NimBLE doesn't even fit into the 51's tiny flash, the 51 doesn't have systick, and so on.