Synthia 2.0 works as an instrument out of the box, and coding it is optional — but it is where the second half of the fun lives.
Start with CircuitBlocks at code.circuitmess.com. It runs in a desktop browser — a Chromium browser (Chrome, Edge or Opera) or an up-to-date version of Firefox; Safari cannot connect to the hardware — and you build programs from drag-and-drop blocks while it writes real MicroPython underneath. The beginner-friendly Synthia coding guide at circuitmess.com/blogs/resources walks you through the first project.
Two things worth knowing before you start
Your last program stays on the device. When you press Run, the program is saved to Synthia and starts again on its own after a power cycle. Only the last program you ran is kept, and your sketches stay saved in your CircuitBlocks account. The detail is in What happens to my CircuitBlocks program when the device resets?.
You can always go back. The Restore firmware button in CircuitBlocks puts the standard instrument back exactly as it shipped, so nothing you try is permanent.
Ready for more? The advanced routes — typing MicroPython directly, or moving to C++ — are laid out in What programming languages can I use with CircuitMess kits?.