Add environment variable for PPS output, and update CI

Author: Johannes Cornelis Draaijer

.github/workflows/build.yml

@@ -132,6 +132,8 @@ jobs:
             features: ""
           - example: rtic-echo
             features: smoltcp-phy
+          - example: rtic-timestamp
+            features: ""
         mcu:
           - stm32f107
           - stm32f429
@@ -143,19 +145,23 @@ jobs:
         pins:
           - nucleo
           - default
+        pps:
+          - default
+          - alternate
+
     steps:
       - name: Checkout
         uses: actions/checkout@v3
 
-      - name: Install Rust ${{ matrix.toolchain }} with target (${{ matrix.target }}) and pins ${{ matrix.pins }}
+      - name: Install Rust ${{ matrix.toolchain }} with target (${{ matrix.target }})
         run: |
           rustup set profile minimal
           rustup override set ${{ matrix.toolchain }}
           rustup target add ${{ matrix.target }}
 
-      - name: Build example ${{ matrix.example.example }} for ${{ matrix.mcu }}
+      - name: Build example ${{ matrix.example.example }} for ${{ matrix.mcu }}, eth pins ${{ matrix.pins }}, pps pin ${{ matrix.pps }}
         run: |
-          STM32_ETH_EXAMPLE_PINS=${{ matrix.pins }} cargo build --release --target=${{ matrix.target }} --example ${{ matrix.example.example}} --features ${{ matrix.mcu }},${{ matrix.example.features }}
+          STM32_ETH_EXAMPLE_PPS=${{ matrix.pps }} STM32_ETH_EXAMPLE_PINS=${{ matrix.pins }} cargo build --release --target=${{ matrix.target }} --example ${{ matrix.example.example}} --features ${{ matrix.mcu }},${{ matrix.example.features }}
 
   # Refs: https://github.com/rust-lang/crater/blob/9ab6f9697c901c4a44025cf0a39b73ad5b37d198/.github/workflows/bors.yml#L125-L149
   #

README.md

@@ -98,12 +98,14 @@ The examples should run and compile on any MCU that has an 802.3 compatible PHY
 
 The examples use `defmt` and `defmt_rtt` for logging, and `panic_probe` over `defmt_rtt` for printing panic backtraces.
 
-##### Alternative pin configuration & HSE
+##### Alternative pin configuration, HSE & PPS
 
 If the board you're developing for has a High Speed External oscillator connected to the correct pins, the HSE configuration can be activated by setting the `STM32_ETH_EXAMPLE_HSE` environment variable to one of `oscillator` or `bypass` when compiling.
 
 If the board you're developing for uses the nucleo pinout (PG11 and PG13 instead of PB11 and PB12), the pin configuration can be changed by setting the `STM32_ETH_EXAMPLE_PINS` environment variable to `nucleo` when compiling.
 
+If you wish to use the alternative PPS output pin (PG8 instead of PB5) for the `rtic-timestamp` example, the pin configuration can be changed by setting the `STM32_ETH_EXAMPLE_PPS_PIN` environment variable to `alternate` when compiling.
+
 ### Building examples
 To build an example, run the following command:
 ```bash

build.rs

@@ -24,6 +24,17 @@ fn main() {
         }
     }
 
+    let pps_pin = std::env::var("STM32_ETH_EXAMPLE_PPS_PIN");
+
+    if let Ok(pps_pin) = pps_pin {
+        if pps_pin == "alternate" {
+            println!("cargo:rustc-cfg=pps=\"alternate\"")
+        } else if pps_pin != "default" {
+            panic!("Invalid STM32_ETH_EXAMPLE_PPS_PIN value. Allowed values: alternate, default");
+        }
+    }
+
+    println!("cargo:rerun-if-env-changed=STM32_ETH_EXAMPLE_PPS_PIN");
     println!("cargo:rerun-if-env-changed=STM32_ETH_EXAMPLE_HSE");
     println!("cargo:rerun-if-env-changed=STM32_ETH_EXAMPLE_PINS");
 }