New Kastle Firmware

Kastle Drum Firmware is here!

This one looks like a hoot but how to upload it on there?


I found this on the Bastl homepage. „Kastle is an open source DIY project which runs on two Attiny 85 chips that can be reprogrammed with an Arduino (google: “programming Attiny 85 with Arduino”). One chip is dedicated to sound generation while the other one handles modulation.“


Excellent, thank you!!



To do this it looks like I need an arduino and a breadboard. Might as well order new ATtiny chips and just flash and swap them rather than risking the stock chips.


Are you going for it? Please keep us updated :slight_smile:


Wow - I didn’t know this was a thing. I sold my original Kastle with the intention of getting a v1.5 but haven’t got around to it yet.

I just ordered 4 x ATtiny 85 chips and a really handy usb chip programmer that lets me skip the breadboard and arduino

Will post again once i’m able to get the firmware onto the new chips and get them into the Kastle


my entire live set-up is [was pre-lockdown] just two kastle v1.5 + maker hart s mixer controlled by a bitranger synapsis [sometimes radio sometimes circuit-bent casio, sometimes lil olympus field recorder, etc] through altec lancing acs90 monitors

v1.5 is a powerful synth. it definitely sounds like a kastle and is very limited. but whats overlooked a lot is the second output, which is a dedicated left and right trs jack [ive clocked eurorack w kastle as leader, modulated self oscillating gear/diy projects, its endless] also casperelectronics’s synapsis button matrix makes the synth playable on a whole other level, kind of turns it into an “instrument” as they say


I’m so curious to hear more about connecting a button matrix to make it playable. I’ve seen a youtube video using a Korg SQ-1 with CV & Gate to control the Kastle.

anywhere to order this in the USA?

I’ve not seen the Synapsis before. That’s such a simple but superb idea for a companion unit! I have the opportunity to get a Bitranger for £150 at the moment but I’ve spent a lot on synths lately so I’m on the fence about it a little

sq-1 would definitely work if youre keeping it “monophonic”

unlike sq-1 synapsis uses the same baby patch cables [bables] kastle/softpop/etc so youre effectively rerouting the signal flow within the synth

[man i really shouldve made the kastle+synapsis video when bastl asked me to but the space was really not set up for it at the time]… its pretty straight forward breadboard style patching works p much the same as bitranger but cuter


its a small batch limited run, gas is real

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not sure but noise kitchen… im happy sending you my green top a/o wooden top

Is there footage anywhere of the live setup you described (with the Kastle and circuit bent instruments?) - it sounds incredible!

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I have a Kastle, it’s a great little device. Have thought about getting a Synapsis in the past, this discussion makes me think I should make the leap! It’s passive isn’t it? I assume it could be used for other mini patch cable devices (like a volca modular) too as long as you kept an eye on the voltages?

looking at that drum code, they converted a bunch of samples to wavetables, but those .h files are all commented out except #include “TR_HH_AT.h”, and that one actually has 4 samples in it. The problem is I don’t see those referenced anywhere in the main code.
So this leads me to believe that the drum firmware does not use samples as wavetables.
For that we should be looking at kastleSampler instead. Anyone try this?

However I do see references to decay envelopes in the kastledrum code so maybe it is actually synthesizing the drums?

check maybe these are the samples he meant

way out of my depth but this sounds like pulse code modulation or PCM of casio-pk fame a sample-based pseudo-fm converted to digital [1s & 0s] coincidentally pcm had enough processing power to spare for vibrato/delay on some instrument presents sort of like a decay envelope

thank you! support the netlabel!!

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synapsis is totally passive yes, should be fine w volca modular +/-3.3v since attiny85 range 2.7-5.5v