Feature/call tone 2 (#3)

* added 1750Hz call-tone option
* bumped version to 0.2.0
* Updated README.md

.github/workflows/rust.yml

@@ -19,22 +19,29 @@ jobs:
     - name: Cache Rust packages
       uses: actions/cache@v3
       with:
-        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('Cargo.lock') }}
+        key: ${{ runner.os }}-build-${{ hashFiles('Cargo.lock') }}
         path: |
           ~/.cargo
-    - name: Build
-      run: cargo build --verbose --release
     - name: Install elf2uf2-rs
       run: |
         sudo apt-get update
-        sudo apt-get install -y libudev-dev 
+        sudo apt-get install -y libudev-dev
         cargo install elf2uf2-rs
-    - name: Generate uf2 file
-      run: elf2uf2-rs -v target/thumbv6m-none-eabi/release/subtone
+    - name: Build
+      run: |
+        cargo build --verbose --release --features call-tone
+        mv target/thumbv6m-none-eabi/release/subtone target/thumbv6m-none-eabi/release/subtone-calltone
+        cargo build --verbose --release
+    - name: Generate uf2 files
+      run: |
+        elf2uf2-rs -v target/thumbv6m-none-eabi/release/subtone-calltone
+        elf2uf2-rs -v target/thumbv6m-none-eabi/release/subtone
     - name: Archive production artifacts
       uses: actions/upload-artifact@v3
       with:
         name: firmware-binaries
         path: |
           target/thumbv6m-none-eabi/release/subtone
           target/thumbv6m-none-eabi/release/subtone.uf2
+          target/thumbv6m-none-eabi/release/subtone-calltone
+          target/thumbv6m-none-eabi/release/subtone-calltone.uf2

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 edition = "2021"
 name = "subtone"
-version = "0.1.0"
+version = "0.2.0"
 license = "MIT"
 resolver = "2"
 
@@ -100,3 +100,7 @@ debug-assertions = false
 incremental = false
 lto = 'fat'
 opt-level = 's'
+
+[features]
+default = []
+call-tone = []

README.md

@@ -5,9 +5,18 @@ An embedded rust project to generate
 [CTCSS](https://en.wikipedia.org/wiki/Continuous_Tone-Coded_Squelch_System)-Tones
 via [PDM](https://en.wikipedia.org/wiki/Pulse-density_modulation) on a cheap
 [RP2040](https://en.wikipedia.org/wiki/RP2040) board.
+Due to PDM (aka Delta-Modulation) a simple rc-filter is sufficient for
+DA-conversation.
+(eg. 100Ω/3.3µF if not using 1750Hz option or 100Ω/470nF otherwise)
+Prefer tantalum caps for better switching supression.
 
 ![prototype](Prototype.jpg "Prototype attached to 23cm tranciever")
 
+Waveform Example
+----------------
+
+![waveform](Oscilloscope.png "Waveform example on oscilloscope")
+
 Schematics
 ----------
 
@@ -21,4 +30,6 @@ Usage
 
 * Use rotary encoder to select wanted frequency.
 * Press button short for on/off toggling.
-* Press long to store current setting.
+* Press long to store current setting.
+* With 1750Hz call-tone option on this frequency short button push just emmits
+  a one second sine pulse and is quiet otherwise.

build.rs

@@ -82,7 +82,7 @@ fn bmp2bitstr(s: &str) -> String {
 
 fn fontset(p: PathBuf) {
     let sources = [
-        "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "space", "dash", "dot", "off", "mem",
+        "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "space", "tone", "dot", "off", "mem",
     ];
     let mut bitmaps = "".to_string();
     for filename in sources {
@@ -139,22 +139,24 @@ fn main() {
 
     let pdm = pdm_table(1 << PDM_BITS, i_sine);
     // 8 cycles in one table for higher frequencies
-    let pdm_8 = pdm_table(1 << PDM_BITS, |i, s| i_sine(i * 8, s));
+    let pdm_8 = pdm_table(1 << PDM_BITS, |i, s| i_sine(i << 3, s));
     let clk_div_1hz = 125_000_000.0 / 2.0f32.powi(PDM_BITS as i32);
     write(
         out.join("pdm_table.rs"),
         format!(
             "\
 const PDM_TABLE: [u32; {}] = {:?};\n\
-#[allow(dead_code)]\n\
 const PDM8_TABLE: [u32; {}] = {:?};\n\
 const CLK_DIV_1HZ: f32 = {};\n\
+#[allow(dead_code)]\n\
+const CLK_DIV_8HZ: f32 = {};\n\
 ",
             pdm.len(),
             pdm,
             pdm_8.len(),
             pdm_8,
             clk_div_1hz,
+            clk_div_1hz * 8.0,
         ),
     )
     .unwrap();