diff --git a/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/images/synth_drawio.svg b/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/images/synth_drawio.svg new file mode 100644 index 00000000000..6622af2d1de --- /dev/null +++ b/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/images/synth_drawio.svg @@ -0,0 +1,4 @@ + + + +
STM32 Dev Board
STM32 Dev Boa...
Mechanical Keyboard Switches (GPIO)
Mechanical Ke...
ILI9341 Display
(SPI, GPIO)
ILI9341 Displ...
Potentiometers (ADC)
Potentiometer...
Encoder
(Timer)
Encoder(Timer)
PCM5102 DAC module
PCM5102 DAC m...
External speaker(s)
External spea...
3.5mm jack
3.5mm jackText is not SVG - cannot display \ No newline at end of file diff --git a/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/images/synth_schematic.webp b/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/images/synth_schematic.webp new file mode 100644 index 00000000000..f76ac019722 Binary files /dev/null and b/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/images/synth_schematic.webp differ diff --git a/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/index.md b/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/index.md new file mode 100644 index 00000000000..5d6cc765110 --- /dev/null +++ b/website/versioned_docs/version-acs_cc/project/2026/george.carpinisan/index.md @@ -0,0 +1,116 @@ +# Digital Synthesizer + +Polyphonic synthesizer with DSP effects. + +:::info + +**Author**: Cărpinișan George \ +**GitHub Project Link**: https://github.com/UPB-PMRust-Students/acs-project-2026-george17c + +::: + +## Description + +A bare-metal polyphonic synth built with Rust. This project is a 48kHz multi-effect audio engine running on an STM32 NUCLEO-U545RE-Q. It features high-level DSP and a hardware interface for instant feedback. It uses a custom-designed top panel interface to hold the controls for a real-time I2S digital audio stream. + +## Motivation + +I like music and I'm fascinated by the hardware behind it. My goal is to recreate a studio-grade musical instrument, to the best of my ability. +My synth will have some iconic effects and functionalities from a modern synthesizer for a fraction of its price. + +## Architecture + +![Architecture](images/synth_drawio.svg) + +The system is designed around a non-blocking, async pipeline: + +* **Clock Generation:** Used a hardware clock to guarantee a 48 kHz audio sample rate, alongside an 80 MHz CPU clock for DSP overhead. +* **User Interface (EXTI/GPIO/SPI):** Handles asynchronous hardware interrupts from physical components to trigger notes and modify effect parameters. Presets and effects are displayed on an LCD screen. +* **DSP Engine:** Computes multiple oscillators and applies effects in real-time. +* **DMA Controller:** Moves audio blocks from RAM to the audio peripheral without interrupting the CPU. +* **SAI/I2S Peripheral:** Formats the raw data stream into standard I2S frames and sends them to the external DAC. + +## Log + +### Week 13 - 19 April + +* Wrote the initial DSP logic (oscillators, phase modulation, filtering) in a high-level environment ([rodio](https://crates.io/crates/rodio)). +* Started researching components and different top-panel layouts. +* Ordered the first batch of components. + +### Week 20 - 26 April + +* Started the mechanical assembly. +* Configured hardware clocks and initialized the I2S communication with the DAC. Tested its output (a C note from a pulse wave) on my headphones and speaker. Works! + +### Week 27 April - 3 May + +* Finished designing the top panel in AutoCAD. +* Started working on the screen interface for preset selection and effect visualization. + +### Week 4 - 10 May + +* Received the panel. +* Soldered jumper wires on the switches (GPIO pin) and daisy chained their GND pins. +* Soldered wires on the potentiometers. +* Fixed the DAC clock speed, the square wave sounded correctly by chance (it's more tolerant than a sine wave which needs to be sampled more accurately). + +### Week 11 - 17 May + +* Polished the preset logic, made the effect parameters more robust. Only changing their value when a corresponding potentiometer is close to the previous stored value. +* Resoldered some GND pins on the keyboard. + +### Week 18 - 24 May + +* Assembled all the components using a breadboard as a VCC and GND bus. Found out the potentiometers are not properly powered using the breadboard. +* Finished soldering on the proto board. + +## Hardware + +* STM32 NUCLEO-U545RE-Q: processing unit. +* Mechanical keyboard switches, 10k potentiometers, EC11 rotary encoder: to shape the sound. +* 2.8" LCD display: interface for visualizing effects. +* PCM5102 DAC module: for output. +* Power bank: main power supply. +* Wooden box + laser-cut panel. + +### Schematics + +![Schematic](images/synth_schematic.webp) + +### Bill of Materials + +| Device | Usage | Price | +|--------|-------|-------| +|[STM32 NUCLEO-U545RE-Q](https://www.st.com/en/evaluation-tools/nucleo-u545re-q.html) | Microcontroller | [~115 RON](https://ro.farnell.com/stmicroelectronics/nucleo-u545re-q/development-brd-32bit-arm-cortex/dp/4216396?CMP=e-email-sys-orderack-GLB) | +|[Keyboard Switches](https://www.mouser.com/datasheet/2/71/EN_CHERRY_MX_RED-2322150.pdf)|For triggering notes, navigating the display and using the sequencer|[20 x 0.9 RON](https://qwertykey.ro/products/switchuri-outemu-red)| +|[10k potentiometers](https://www.futurlec.com/Potentiometers/POT10K.shtml)|For changing effect parameters|[8 x 1.31 RON](https://sigmanortec.ro/Potentiometru-1K-5K-10K-20K-50K-100K-p136286400)| +|[Rotary Encoder](https://www.farnell.com/datasheets/1837001.pdf)|For navigating the display|[2 x 4.39 RON](https://sigmanortec.ro/Encoder-rotativ-cu-click-20mm-EC11-p128736611)| +|[2.8" LCD display](https://www.lcdwiki.com/res/MSP2807/2.8inch_SPI_Module_MSP2807_User_Manual_EN.pdf)|For visualizing presets and effects|[55.08 RON](https://www.emag.ro/display-lcd-2-8-240x320-pixeli-slot-micro-sd-tactil-4-a-034/pd/DJCT01MBM/)| +|Electronics kit|For wires, breadboard|[39.21 RON](https://www.emag.ro/kit-start-componente-electronice-ai777/pd/DXRJ4TMBM/?ref=history-shopping_484876592_230588_1)| +|[PCM5102 DAC module](https://www.ti.com/lit/ds/symlink/pcm5102-q1.pdf)|For audio output|[37.50 RON](https://www.emag.ro/modul-convertor-audio-digital-analog-dac-pcm5102-calitate-audio-superioara-2-1-vrms-cu-tehnologia-directpathtm-dimensiuni-compacte-perfect-pentru-sisteme-audio-diy-si-placa-de-sunet-externa-7570977565/pd/D1D2W83BM/)| +|10 cm female-female wires|To solder on switches|[1 x 6.99 RON](https://www.optimusdigital.ro/en/wires-with-connectors/652-10-cm-40p-female-female-wire.html)| +|10 cm female-male wires|For the VCC and GND pins of the DAC and display|[2 x 3.99 RON](https://www.optimusdigital.ro/en/wires-with-connectors/650-fire-colorate-mama-tata-10p.html) +|Proto boards|To act as a VCC and GND bus|[2 x 1.28 RON](https://www.optimusdigital.ro/en/protoboards/722-20x80-mm-green-universal-prototyping-board.html)| +|Wooden box|Case for the whole circuitry| [34 RON](https://www.profiart.ro/catalog/q/cutie%20mdf)| +|Laser-cut top panel|For the user controlled knobs and switches| 0 RON | + +## Software + +| Library | Description | Usage | +|---------|-------------|-------| +| [embassy-stm32](https://github.com/embassy-rs/embassy) | Async HAL for STM32 | Main hardware abstraction for GPIO, SAI, DMA, SPI, and Clocks. | +| [mipidsi](https://github.com/almindor/mipidsi) | Multi-display driver | Modern driver for the ILI9341 display, compatible with `embedded-graphics`. | +| [display-interface-spi](https://github.com/almindor/display-interface) | Generic SPI display interface | Provides the communication layer between the SPI peripheral and the display driver. | +| [embedded-graphics](https://github.com/embedded-graphics/embedded-graphics) | 2D graphics library | Core library for drawing shapes, images, and basic text on the display. | +| [micromath](https://github.com/tarcieri/micromath) | Embedded math library | Provides optimized trigonometric and math functions (sin, cos, exp) for the DSP engine. | +| [static_cell](https://github.com/embassy-rs/static-cell) | Statically allocated memory | Allows safe runtime initialization of values with a `'static` lifetime, for sharing resources with async tasks without a heap memory manager. | +| [heapless](https://github.com/japaric/heapless) | Fixed-capacity data structures | Provides structures `String`, or `RingBuffer` with static capacities, preventing runtime allocation panics while handling UI state buffers. | +| [defmt](https://github.com/knurling-rs/defmt) | Efficient logging | Used for debugging | + +## Links + + +1. [ How to create "On the Run" by Pink Floyd pattern on Behringer TD-3 (303) ](https://www.youtube.com/watch?v=mCpNF3-radE&list=PLlWYrAERc9u-2KVlG_TCtRS1XzZzfO4SF&index=7) +2. [ Synthesis Basics: How To Ring Mod, FM, and AM ](https://www.youtube.com/watch?v=p23e7xmL6I4&list=PLlWYrAERc9u-2KVlG_TCtRS1XzZzfO4SF&index=6) +3. [ The Math Behind Music and Sound Synthesis ](https://www.youtube.com/watch?v=Y7TesKMSE74&list=PLlWYrAERc9u-2KVlG_TCtRS1XzZzfO4SF&index=4)