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 Hale Ltd. is a small consultancy offering bespoke hand-crafted electronics, prototypes and curios.

Thursday 30 March 2023

C3 Basic

The ESP32-C3 is proving to be a really great option for a 'basic' microcontroller that still has lots of Flash, SRAM and tons of features.

So we designed a small development board for putting in battery powered projects and christened it the 'C3 Basic'.

With onboard USB Serial/JTAG you need precious little to make a viable board and it can be clocked down to 10Mhz if you're not using the Wi-Fi or Bluetooth features.

There aren't as many GPIO as the rest of the Espressif ESP32 stable, but it's just enough to do basic projects with.

At launch there was a lot of fuss about the C3 being a RISC-V core but in practice the Espressif toolchain just makes it look like another ESP32, especially if you're using another layer of abstraction and programming it in the Arduino IDE.

You can put headers on but I'd normally expect this to get permanently soldered in. It's how we'll be using them.

The USB connection is easy, just four wires and while you nominally should be careful about routing it, the low speed Serial USB is tolerant of dangling a USB socket on then end of some random wires. Or in this case, just jamming a USB breakout in the header holes.

As it's never clear what battery somebody might want in a project we haven't included any form of charger and you should never connect USB power and the battery at the same time, unless you've arranged some kind of protection or charger yourself.

The onboard buck convertor is tolerant of up to 6.0v. We'd expect the C3 Basic to be run off a single LiPo, three alkaline or four NiMh cells depending on what you're happy with and for battery monitoring there is a resistor ladder on GPIO 0 that halves the battery voltage. The monitoring resistors are permanently in circuit so this isn't an ideal board if you want very long deep sleep battery life, but at 440k they're not going to noticeably affect something running normally.

We'll be offering these for sale on Tindie at some point.

There's a fair likelihood we'll develop another version with onboard LiPo charging for our own use if nothing else.