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Comment by brucehoult | Hacker News Reader

The article goes through a long list of 8 pin chips but ignores the very popular $0.10 CH32V003, which has 2k RAM and 16k Flash running at 48 MHz and 1 CPI -- or the new CH570 (I have a dev board on the way) which is also $0.10 in SOIC8 but now runs at 100 MHz with 16k RAM and 256k flash and has USB and a 2.4 GHz packet radio.

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CH32V003 is not available on mouser.com or digikey.com

Googling for "CH570" produces results about tractors. Got a link?

EDIT: found info here: https://www.cnx-software.com/2025/04/02/10-cents-wch-ch570-c...

8-pin part lacks USB AND only has 3 I/O pins. It would be disqualified due to being too I/O-poor. Wasting 5 pins out of 8 is a joke!

As for the old one, CH32V003: 48MHz is slower than the STM's 150MHz, half the flash, 1/4 the RAM. It is still not the best option.

I did update the article with them, though :)

> 8-pin part lacks USB AND only has 3 I/O pins

But you get radio (BLE in the CH572 version), which means you don't need USB.

My comment was not that you didn't choose them but that you didn't consider them.

You do NOT get BLE in the 8-pin part

I just considered them and added them to my writeup :)

You get the radio in the 8 pin part. That's the "ANT" connection, pin 8, one of the three "wasted" pins (along with the crystal) you complain about.

Yup. All of which would be useless for this project. :)

I am imagining a world where Bruce and Dmitry team up on a project together, maybe we need CNLohr as arbiter.

I bow to both Dima and Charles on making practical physical hack projects!

I'm more of a software guy. I guess my biggest hardware project (other than building a 3D printer from someone else's plans) was in 2012 or so making a PID-based home heating controller using an Uno with a custom perfboard shield with a thermistor for measuring the air temperature and a 433 MHz transmitter for talking to a set of Jaycar 240V remote controlled power outlets to control primarily a 2400W oil column heater, plus a fan pointing at it which I turned on when it was at a high duty cycle. Plus switching the home water heating on and off on a fixed schedule just as a side thing from the same board. I used that in Wellington for 3 winters before moving to Russia for a few years and saved NZ$500 per winter on electricity bills compared to previous years using a mechanical Honeywell thermostat to control the heater.

That is really cool. Sounds like it could be turned into a great product. It is funny that Nest basically added 3 if statements to a thermostat over a reed thermal switch and became a multibillion dollar company for it.

It worked really well. That Honeywell thing let the temperature cycle over maybe a 2º C range. I was sampling the thermistor 100 times in about 1/10th of a second (analogRead() on Arduino) and then doing exponential averaging each second with a 32 second time constant (i.e. `temp = temp - (temp >> 5) + new_reading`) and averaging and getting a nice stable temperature reading that moved smoothly in 0.01º C increments. Turning the heater on and off at maximum every 30 seconds the room temp usually stayed within ±0.03 C of the set temperature -- not precise on an absolute scale but detecting and correcting small changes accurately.

I was actually thinking of trying to make a product, especially once Flick Electric started up with electricity prices changing every 30 minutes based on the wholesale rate plus a 2c margin. You could (still can) get the current 30 minute wholesale price at your local substation from electricityinfo.co.nz with a simple http query, so you can build something to make intelligent decisions.

But then I got a job overseas and dropped the project...

2.4Ghz. I was really wondering about the 24Ghz.

oops .. my brain of course knows but my fingers didn't in this instance. Fixed.

I think it's compatible with the old nRF24 chips -- I'll test when mine arrives in a week or so. The CH572 version has BLE5 ... I think the same hardware but including a software stack.

Damn, only one seller on Aliexpress right now and no dev boards. Where’d you find yours?

The official WCH store on Aliexpress. Stock is coming in slowly 10 at a time and then selling out in 30 minutes or so, but it is coming in.

https://www.aliexpress.com/item/1005008743123631.html

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