feat: more piano features

- basic velocity detection
- pedal

Cargo.lock

@@ -771,7 +771,7 @@ dependencies = [
 ]
 
 [[package]]
-name = "geode-piano"
+name = "geode_piano"
 version = "0.1.0"
 dependencies = [
  "byte-slice-cast 1.2.2",

Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "geode-piano"
+name = "geode_piano"
 version = "0.1.0"
 edition = "2021"
 license = "GPL-3.0-only"

README.md

@@ -2,15 +2,17 @@
 
 Digital piano firmware for the Raspberry Pi Pico.
 This project only attempts to expose the keyboard as a MIDI device.
+The purpose is to revive digital pianos that have working keys, but faulty electronics.
 
 ## installation
 
 - Clone project.
 - Go into project directory.
+- Install the `thumbv6m-none-eabi` target using rustup.
 - Install `elf2uf2-rs`.
 - Follow the materials and wiring sections below.
 - Set the Pico into BOOTSEL mode:
-    - Hold down the BOOTSEL button on the Pico. Keep holding it during the following steps.
+    - Hold down the BOOTSEL button on the Pico. Keep holding it during the following step.
     - Reset the Pico: either replug the power, or short Pin 30 (RUN) to GND through a button or wire.
 - Mount the Pico's storage on your device.
 - `cargo run --release --bin [binary]`
@@ -18,15 +20,44 @@ This project only attempts to expose the keyboard as a MIDI device.
 
 If you are missing dependencies, consult [Alex Wilson's guide](https://www.alexdwilson.dev/learning-in-public/how-to-program-a-raspberry-pi-pico) on Rust Pico development.
 
+## usage
+
+The intended usage is to first plug the device into the piano keyboard, then use the `pin_scanner` binary to
+scan the key-matrix. (See the next sections on how to wire it up.)
+On every key, press it down half-way and then fully and note the pins connections detected at each level.
+These correspond to the [`midi::KeyAction::N1`] and [`midi::KeyAction::N2`] actions respectively.
+There should be two switches per key for velocity detection.
+If there isn't, then the key is an [`midi::KeyAction::N`] (it will be stuck at a fixed velocity).
+
+Put the connections in a spreadsheet and reorganize it so that GND pins are column headers, and the Input pins are row headers.
+This will comprise the keymap.
+The keymap is a an array with the same dimensions as the spreadsheet grid.
+This is comprised of N1, N2, and N entries, indicating which note a key corresponds to.
+
+Once the keymap is done, run the `piano_firmware` binary and plug the USB cable to your computer.
+Open up a DAW and select Geode-Piano as a MIDI input device.
+I use LMMS with the [Maestro Concert Grand v2](https://www.linuxsampler.org/instruments.html) samples.
+You should be able to play now.
+
 ## materials
 
 - 1 Raspberry Pi Pico (preferably with pre-soldered headers)
 - 2 MCP23017 I/O extender chips, DIP format
-- 2 pull-up resistors for I²C (1-10kΩ), these are optional but recommended
+- 2 pull-up resistors for I²C (1-10kΩ), these are optional but [recommended](https://www.joshmcguigan.com/blog/internal-pull-up-resistor-i2c/)
 - 1 USB to Micro-USB cable with data transfer
+- Ribbon cable sockets. The following is for my own piano, yours might be different:
+    - 18-pin 1.25mm pitch FFC connector
+    - 22-pin 1.25mm pitch FFC connector
 - Many jumper cables
 - Breadboard
 
+For the ribbon cable sockets, open up your piano and find the ribbon cables.
+Unplug them from the PCB, and count the amount of pins on them.
+Also, measure the distance between each pin,
+or the distance between the first and last pin.
+This will help you find the right pin pitch and pin count.
+Usually, these measurements can be found on the datasheets for FFC sockets.
+
 ## wiring
 
 **Ensure all wires are well plugged in every time you use this circuit.** 
@@ -54,3 +85,31 @@ For both MCP23017s:
     - MCP A should be 0x20 (GND, GND, GND), MCP B 0x27 (3V3, 3V3, 3V3)
 - MCP VDD -> power rail
 - MCP VSS -> GND rail
+
+### ribbon cables
+
+Connect the following pins to the ribbon cable sockets in any order (use more or less pins depending on how many you need):
+
+- GP15
+- GP14
+- GP13
+- GP12
+- GP11
+- GP10
+- GP9
+- GP18
+- GP19
+- GP20
+- GP21
+- GP22
+- All MCP GPIO pins except GPB7 and GPA7 on both chips (see [datasheet](https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/MCP23017-Data-Sheet-DS20001952.pdf) for diagram of pins)
+
+GPB7 and GPA7 have known issues and therefore can not be inputs.
+Again, refer to the datasheet about this.
+It is simpler to exclude them instead of working around that limitation.
+
+I used male-to-female jumpers with the female end trimmed to reveal the metal part inside.
+This was necessary to attach to the short pins on the jumpers.
+The opening in the plastic on the female end should face inwards when connected to the sockets.
+
+Then, plug the ribbon cables from your piano into the sockets.

src/bin/piano_firmware.rs

@@ -27,21 +27,23 @@ use embassy_rp::bind_interrupts;
 use embassy_rp::i2c;
 use embassy_rp::peripherals::USB;
 use embassy_rp::usb::{Driver, InterruptHandler};
-use geode_piano::usb::usb_task;
+use geode_piano::matrix;
 use geode_piano::matrix::KeyMatrix;
+use geode_piano::midi;
+use geode_piano::usb::usb_task;
 use geode_piano::{blinky, pin_array, pins, unwrap};
 
 #[embassy_executor::task]
 async fn piano_task(pin_driver: pins::TransparentPins) {
+    use geode_piano::midi::KeyAction::*;
     use geode_piano::midi::Note::*;
 
     // GND pins
-    let col_pins = [23];
+    let col_pins = [23, 24];
     // Input pins
     let row_pins = [20, 15, 4];
     // Notes for each key
-    let keymap = [[C4, D4, E4]];
+    let keymap = [[N1(C4), N1(D4), N1(E4)], [N1(C4), N2(D4), N2(E4)]];
-
     let mut mat = KeyMatrix::new(col_pins, row_pins, keymap);
     mat.scan(pin_driver).await;
 }
@@ -63,7 +65,7 @@ async fn main(_spawner: Spawner) {
     let scl = p.PIN_17;
 
     let mut i2c_config = i2c::Config::default();
-    let freq = 100_000;
+    let freq = 400_000;
     i2c_config.frequency = freq;
     let i2c = i2c::I2c::new_blocking(p.I2C0, scl, sda, i2c_config);
 
@@ -81,4 +83,12 @@ async fn main(_spawner: Spawner) {
 
     log::info!("main: starting piano task");
     _spawner.spawn(piano_task(pin_driver)).unwrap();
+
+    log::info!("main: starting sustain pedal task");
+    _spawner
+        .spawn(matrix::pedal(
+            midi::Controller::SustainPedal,
+            p.PIN_8.into(),
+        ))
+        .unwrap();
 }

src/lib.rs

@@ -1,5 +1,4 @@
 #![doc = include_str!("../README.md")]
-
 #![no_std]
 #![no_main]
 #![deny(rust_2018_idioms)]
@@ -9,10 +8,10 @@ use embassy_time::Timer;
 use {defmt_rtt as _, panic_probe as _};
 
 pub mod blinky;
+pub mod matrix;
 pub mod midi;
 pub mod pins;
 pub mod usb;
-pub mod matrix;
 
 /// Unwrap, but log before panic
 ///

src/matrix.rs

@@ -1,10 +1,24 @@
-//! Key matrix scanner
+//! Key matrix scanner + other interfacing utilities
 
-use crate::pins;
 use crate::midi;
+use crate::pins;
 use crate::unwrap;
+use core::cmp::min;
 use embassy_rp::gpio;
-use embassy_time::{Duration, Ticker};
+use embassy_time::{Duration, Instant, Ticker};
+
+/// Task to handle pedals in MIDI
+#[embassy_executor::task]
+pub async fn pedal(pedal: midi::Controller, pin: gpio::AnyPin) {
+    let mut inp = gpio::Input::new(pin, gpio::Pull::Up);
+    let chan = midi::MidiChannel::new(0);
+    loop {
+        inp.wait_for_low().await;
+        chan.controller(pedal, 64).await;
+        inp.wait_for_high().await;
+        chan.controller(pedal, 0).await;
+    }
+}
 
 /// Key matrix for the piano.
 pub struct KeyMatrix<const N_ROWS: usize, const N_COLS: usize> {
@@ -12,7 +26,7 @@ pub struct KeyMatrix<const N_ROWS: usize, const N_COLS: usize> {
     col_pins: [u8; N_COLS],
     /// Input pins at the left of each row
     row_pins: [u8; N_ROWS],
-    keymap: [[midi::Note; N_ROWS]; N_COLS],
+    keymap: [[midi::KeyAction; N_ROWS]; N_COLS],
 }
 
 impl<const N_ROWS: usize, const N_COLS: usize> KeyMatrix<N_ROWS, N_COLS> {
@@ -25,7 +39,7 @@ impl<const N_ROWS: usize, const N_COLS: usize> KeyMatrix<N_ROWS, N_COLS> {
     pub fn new(
         col_pins: [u8; N_COLS],
         row_pins: [u8; N_ROWS],
-        keymap: [[midi::Note; N_ROWS]; N_COLS],
+        keymap: [[midi::KeyAction; N_ROWS]; N_COLS],
     ) -> Self {
         KeyMatrix {
             col_pins,
@@ -39,9 +53,18 @@ impl<const N_ROWS: usize, const N_COLS: usize> KeyMatrix<N_ROWS, N_COLS> {
             unwrap(pin_driver.set_input(i)).await;
             unwrap(pin_driver.set_pull(i, gpio::Pull::Up)).await;
         }
-        let mut ticker = Ticker::every(Duration::from_millis(10));
+
+        // scan frequency
+        // this might(?) panic if the scan takes longer than the tick
+        let mut ticker = Ticker::every(Duration::from_millis(2));
+
         let chan = midi::MidiChannel::new(0);
-        let mut note_on = [false; 128];
+        const MAX_NOTES: usize = 128;
+
+        // is note currently on
+        let mut note_on = [false; MAX_NOTES];
+        // (for velocity detection) moment key is first touched
+        let mut note_first: [Option<Instant>; MAX_NOTES] = [None; MAX_NOTES];
 
         loop {
             for (i, col) in self.col_pins.iter().enumerate() {
@@ -52,15 +75,46 @@ impl<const N_ROWS: usize, const N_COLS: usize> KeyMatrix<N_ROWS, N_COLS> {
                 // values that are logical ON
                 let mask = input ^ (((1 << pin_driver.n_usable_pins()) - 1) ^ (1 << col));
                 for (j, row) in self.row_pins.iter().enumerate() {
-                    let note = self.keymap[i][j];
+                    let key_action = self.keymap[i][j];
-                    if mask & (1 << row) != 0 {
+                    let key_active = mask & (1 << row) != 0;
-                        if !note_on[note as usize] {
+                    match key_action {
-                            note_on[note as usize] = true;
+                        midi::KeyAction::N1(note) => {
-                            chan.note_on(note, 40).await;
+                            if !note_on[note as usize]
+                                && note_first[note as usize].is_none()
+                                && key_active
+                            {
+                                note_first[note as usize] = Some(Instant::now());
+                            }
+                        }
+                        midi::KeyAction::N2(note) => {
+                            if key_active {
+                                if note_first[note as usize].is_some() && !note_on[note as usize] {
+                                    // millisecond duration of keypress
+                                    let dur =
+                                        note_first[note as usize].unwrap().elapsed().as_millis();
+                                    // 1905 millis is the minimum velocity
+                                    let velocity: u8 = 127 - min(dur / 15, 127) as u8;
+                                    note_first[note as usize] = None;
+                                    note_on[note as usize] = true;
+                                    chan.note_on(note, velocity).await;
+                                }
+                            } else if note_on[note as usize] {
+                                note_on[note as usize] = false;
+                                note_first[note as usize] = None;
+                                chan.note_off(note, 0).await;
+                            }
+                        }
+                        midi::KeyAction::N(note, velocity) => {
+                            if key_active {
+                                if !note_on[note as usize] {
+                                    note_on[note as usize] = true;
+                                    chan.note_on(note, velocity).await;
+                                }
+                            } else if note_on[note as usize] {
+                                note_on[note as usize] = false;
+                                chan.note_off(note, 0).await;
+                            }
                         }
-                    } else if note_on[note as usize] {
-                        note_on[note as usize] = false;
-                        chan.note_off(note, 0).await;
                     }
                 }
             }

src/midi/mod.rs

@@ -189,6 +189,16 @@ pub enum Note {
     B8 = 119,
 }
 
+#[derive(Clone, Copy)]
+pub enum KeyAction {
+    /// Switch that is first triggered when pressing a key.
+    N1(Note),
+    /// Switch triggered when key bottoms out.
+    N2(Note),
+    /// Basic switch with fixed velocity. Be careful not to mix with actions with velocity detection.
+    N(Note, u8),
+}
+
 pub struct Disconnected {}
 
 impl From<EndpointError> for Disconnected {

src/usb.rs

@@ -1,5 +1,6 @@
 //! Handle all USB communcation in this task.
-//! If USB is handled in multiple tasks the code gets weird and unwieldy (`'static` everywhere)
+//!
+//! If USB is handled in multiple tasks the code gets weird and unwieldy (`'static` everywhere).
 //! Code in this file is mostly from the examples folder in embassy-rs.
 
 /*