| Lowebrau | Posted: 31 Jan 2019, 10:13 PM |
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 Member Posts: 2 Joined: 31-January 19 |
Hello, I'm undertaking the MIDI for Korg Monotron project. As I'm waiting for the parts to come in the mail, I was reading the pages on this project. I'm wondering if all the code that needs to be put on the ATtiny85 is what's on the project page: ldi r16, (1<<PLLE|1<<PCKE) out PLLCSR,r16 ldi r16, (1<<PWM1A|1<<COM1A1|1<<CS10) out TCCR1,r16 ldi r16, (1<<PWM1B|1<<COM1B1) out GTCCR,r16 ldi r16,255 out OCR1C,r16 It wasn't entirely clear to me Thanks! ------------- |
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| mit | Posted: 1 Feb 2019, 10:21 PM |
 yeah whatever Admin Posts: 538 Joined: 4-May 16 |
Hi, there's more to it than that. The full source code is on github: https://github.com/mitxela/MidiMonotron I forgot to link to that on the project page (I will update that when I next get a chance) Good Luck! ------------- |
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| Lowebrau | Posted: 9 Feb 2019, 08:24 PM |
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Member Posts: 2 Joined: 31-January 19 |
Ok, thank you for that! ------------- |
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| Carlos_Luna | Posted: 16 Mar 2020, 08:37 PM |
 Member Posts: 1 Joined: 16-March 20 |
Hi there, thanks for sharing your project info. Do you know if I can do the same for a Monotron Delay? I didn't find the "LFO reset" in the schematic. It should be a way, just wondering. Thanks for the great work! Greetings from Mexico ------------- |
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| mit | Posted: 17 Mar 2020, 12:01 AM |
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yeah whatever Admin Posts: 538 Joined: 4-May 16 |
I don't own a monotron delay but it should work. It took a fair bit of experimenting to find the LFO reset on the monotron, it's not clearly labelled like the other signals, but it is labelled on the (non-delay) schematic right in the middle. ------------- |
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| epsteinbarr | Posted: 9 Nov 2020, 11:52 AM |
 Member Posts: 1 Joined: 9-November 20 |
Hello, thanks for sharing your project info. I'm trying to do that on an Attiny2313 (programming it with an arduino UNO board), but i can't figure how to adapt your project to it. There are some hints, or links that can help me? Thanks in advance ------------- |
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| mit | Posted: 9 Nov 2020, 04:13 PM |
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yeah whatever Admin Posts: 538 Joined: 4-May 16 |
The ATtiny2313 is quite a different chip, so you'll basically have to start over from scratch. It has a hardware UART, so that makes things easier (most of the ATtiny85 code is about bitbanging the uart decode). The timers are a lot less flexible so I'm not sure if you'll be able to generate the voltages correctly. ------------- |
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| E18 | Posted: 18 Dec 2021, 01:04 AM |
 Member Posts: 1 Joined: 18-December 21 |
This is very nice work! Can you please elaborate how you dealt with the issue of the gate voltage effecting the pitch? I didn't see a gate output in the schematic. I've been exploring the circuit mods from: http://www.dinsync.info/2010/06/how-to-modify-korg-monotron.html and https://www.youtube.com/watch?v=iT__-bH8Q0o (circuit)https://github.com/matthewcieplak/monotron-cv-adapter How does your circuit overcome the problem of the calibration of Volts/Octave and stability of pitch over time? Both of these other pure-CV mods seem to struggle with both the gate and tuning the Volts/Octave. Thanks. ------------- |
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| mit | Posted: 18 Dec 2021, 01:36 AM |
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yeah whatever Admin Posts: 538 Joined: 4-May 16 |
The gate signal is connected to PB3 of the ATtiny chip. The gate voltage is held steady for the duration of the note, so it doesn't matter that it affects the pitch. I do remember the pitch scale drifting over time, I changed the trimpot out with a small multi-turn one, mounted it next to the TRS socket and made a hole in the case so it can be adjusted with a screwdriver without having to open it up. This was pretty effective, just means you have to adjust it every now and then. ------------- |
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