Rockit Firmware 1.12

Rockit firmware 1.12 is available. The changes are mostly limited to MIDI. I’ve implemented a soft MIDI Thru. Messages not intended for Rockit, meaning on a different channel, are passed through to the MIDI Output. The MIDI channel can now be changed. To change the MIDI channel, hold down the Select button until the display starts flashing. Then, use the Save and Recall buttons to change the MIDI channel. Finally, hold down the select button until the display stops flashing and that’s it. Otherwise, I fixed a bug that caused the audio to stop when the arpeggiator was running and drone mode was entered. That’s about it. Some other transparent changes were made for an improvement in the number of clock cycles required to perform various tasks. Have some fun and let me know if you find any funny business going on. Download the hex file here.

Synth DIY : Software for Generating ADSR Envelopes

I’ve spent a fair amount of time detailing the hardware that Rockit uses for it’s Voltage-Controlled Amplifier. It’s a transconductance amplifier-based design and you can read about it here. I haven’t, however, discussed the software behind implementing the envelope generator. It ends up being more useful than just controlling amplitude. The same envelope generator code works for the filter envelope too. I didn’t end up using exactly the same code, but it could be made entirely modular, taking some basic inputs like timing and parameter data and returning an appropriate value for an envelope. Let’s just focus on how to code an ADSR envelope for now. If you’d like to get the source code for Rockit, please download it from Rockit’s Sourceforge Page.

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