examples: nrf52840: Support customising LoRaWAN keys via ENV

Add possibility to overriding LoRaWAN keys from env during compile.

examples/nrf52840/Cargo.toml

@@ -26,6 +26,7 @@ debug = 2
 
 [features]
 default = []
-
-## Customize target binary to make it runnable from RAM (ie via teleprobe)
+## Customize target binary to make it runnable from RAM
 link-to-ram = []
+# Add teleprobe specific hooks to code
+teleprobe = ["link-to-ram"]

examples/nrf52840/build.rs

@@ -10,14 +10,77 @@
 
 use std::env;
 use std::fs::File;
-use std::io::Write;
+use std::io::{BufWriter, Write};
 use std::path::PathBuf;
 
+fn hex_to_bytes(s: &str) -> Option<Vec<u8>> {
+    if s.len() % 2 == 0 {
+        (0..s.len())
+            .step_by(2)
+            .map(|i| s.get(i..i + 2).and_then(|sub| u8::from_str_radix(sub, 16).ok()))
+            .collect()
+    } else {
+        None
+    }
+}
+
+/// Read and parse LoRaWAN keys as HEX strings from an environment variable
+fn parse_lorawan_id(val: Option<&str>, var: &str, len: usize) -> Option<String> {
+    if let Some(s) = val {
+        let l = s.len();
+        // Allow empty keys
+        if l == 0 {
+            return None;
+        }
+        if l % 2 == 1 || l != 2 * len {
+            panic!(
+                "Environment variable {} has invalid length: {}, expecting: {}",
+                &var,
+                l,
+                2 * len
+            );
+        }
+        if let Some(v) = hex_to_bytes(s) {
+            return Some(format!("Some({:?})", v));
+        } else {
+            panic!(
+                "Unable to parse {} from environment, make sure it's a valid hex string with length {}",
+                &var,
+                2 * len
+            );
+        }
+    }
+    None
+}
+
 fn main() {
-    // Put linker configuration in our output directory and ensure it's
-    // on the linker search path.
     let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
 
+    // Generate LoRaWAN eui and key overrides from environment variables
+    {
+        let path = &out.join("lorawan_keys.rs");
+        let mut file = BufWriter::new(File::create(&path).unwrap());
+
+        // TODO: Figure out how to not generate this file every time...
+        write!(
+            &mut file,
+            "{}",
+            format_args!(
+                "\
+            // Generated by build.rs\n\
+            const DEVEUI: Option<[u8; 8]> = {};\n\
+            const APPEUI: Option<[u8; 8]> = {};\n\
+            const APPKEY: Option<[u8; 16]> = {};\n",
+                parse_lorawan_id(option_env!("LORA_DEVEUI"), "LORA_DEVEUI", 8).unwrap_or("None".to_string()),
+                parse_lorawan_id(option_env!("LORA_APPEUI"), "LORA_APPEUI", 8).unwrap_or("None".to_string()),
+                parse_lorawan_id(option_env!("LORA_APPKEY"), "LORA_APPKEY", 16).unwrap_or("None".to_string()),
+            )
+        )
+        .unwrap();
+    }
+
+    // Put linker configuration in our output directory and ensure it's
+    // on the linker search path.
     if cfg!(feature = "link-to-ram") {
         File::create(out.join("link_ram_cortex_m.x"))
             .unwrap()

examples/nrf52840/src/bin/lora_cad.rs

@@ -11,7 +11,7 @@ use embassy_nrf::{bind_interrupts, peripherals, spim};
 use embassy_time::{Delay, Timer};
 use embedded_hal_bus::spi::ExclusiveDevice;
 use lora_phy::iv::GenericSx126xInterfaceVariant;
-use lora_phy::sx126x::{Sx126xVariant, TcxoCtrlVoltage, Sx126x};
+use lora_phy::sx126x::{Sx126x, Sx126xVariant, TcxoCtrlVoltage};
 use lora_phy::LoRa;
 use lora_phy::{mod_params::*, sx126x};
 use {defmt_rtt as _, panic_probe as _};

examples/nrf52840/src/bin/lora_lorawan.rs

@@ -13,7 +13,7 @@ use embassy_time::Delay;
 use embedded_hal_bus::spi::ExclusiveDevice;
 use lora_phy::iv::GenericSx126xInterfaceVariant;
 use lora_phy::lorawan_radio::LorawanRadio;
-use lora_phy::sx126x::{self, Sx126xVariant, TcxoCtrlVoltage, Sx126x};
+use lora_phy::sx126x::{self, Sx126x, Sx126xVariant, TcxoCtrlVoltage};
 use lora_phy::LoRa;
 use lorawan_device::async_device::{region, Device, EmbassyTimer, JoinMode};
 use lorawan_device::default_crypto::DefaultFactory as Crypto;
@@ -24,6 +24,15 @@ use {defmt_rtt as _, panic_probe as _};
 const LORAWAN_REGION: region::Region = region::Region::EU868;
 const MAX_TX_POWER: u8 = 14;
 
+// Load optional override values for EUIs and APPKEY generated by build.rs from
+// environment values
+include!(concat!(env!("OUT_DIR"), "/lorawan_keys.rs"));
+
+// Fallback values
+const DEFAULT_DEVEUI: [u8; 8] = [0, 0, 0, 0, 0, 0, 0, 0];
+const DEFAULT_APPEUI: [u8; 8] = [0, 0, 0, 0, 0, 0, 0, 0];
+const DEFAULT_APPKEY: [u8; 16] = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
+
 bind_interrupts!(struct Irqs {
     SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1 => spim::InterruptHandler<peripherals::TWISPI1>;
     RNG => rng::InterruptHandler<peripherals::RNG>;
@@ -60,15 +69,17 @@ async fn main(_spawner: Spawner) {
 
     defmt::info!("Joining LoRaWAN network");
 
-    // TODO: Adjust the EUI and Keys according to your network credentials
     let resp = device
         .join(&JoinMode::OTAA {
-            deveui: DevEui::from([0, 0, 0, 0, 0, 0, 0, 0]),
-            appeui: AppEui::from([0, 0, 0, 0, 0, 0, 0, 0]),
-            appkey: AppKey::from([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]),
+            deveui: DevEui::from(DEVEUI.unwrap_or(DEFAULT_DEVEUI)),
+            appeui: AppEui::from(APPEUI.unwrap_or(DEFAULT_APPEUI)),
+            appkey: AppKey::from(APPKEY.unwrap_or(DEFAULT_APPKEY)),
         })
         .await
         .unwrap();
 
     info!("LoRaWAN network joined: {:?}", resp);
+
+    #[cfg(feature = "teleprobe")]
+    cortex_m::asm::bkpt();
 }

examples/nrf52840/src/bin/lora_p2p_receive.rs

@@ -11,7 +11,7 @@ use embassy_nrf::{bind_interrupts, peripherals, spim};
 use embassy_time::{Delay, Timer};
 use embedded_hal_bus::spi::ExclusiveDevice;
 use lora_phy::iv::GenericSx126xInterfaceVariant;
-use lora_phy::sx126x::{Sx126xVariant, TcxoCtrlVoltage, Sx126x};
+use lora_phy::sx126x::{Sx126x, Sx126xVariant, TcxoCtrlVoltage};
 use lora_phy::{mod_params::*, sx126x};
 use lora_phy::{LoRa, RxMode};
 use {defmt_rtt as _, panic_probe as _};

examples/nrf52840/src/bin/lora_p2p_receive_duty_cycle.rs

@@ -11,7 +11,7 @@ use embassy_nrf::{bind_interrupts, peripherals, spim};
 use embassy_time::{Delay, Timer};
 use embedded_hal_bus::spi::ExclusiveDevice;
 use lora_phy::iv::GenericSx126xInterfaceVariant;
-use lora_phy::sx126x::{Sx126xVariant, TcxoCtrlVoltage, Sx126x};
+use lora_phy::sx126x::{Sx126x, Sx126xVariant, TcxoCtrlVoltage};
 use lora_phy::{mod_params::*, sx126x};
 use lora_phy::{LoRa, RxMode};
 use {defmt_rtt as _, panic_probe as _};

examples/nrf52840/src/bin/lora_p2p_send.rs

@@ -11,7 +11,7 @@ use embassy_nrf::{bind_interrupts, peripherals, spim};
 use embassy_time::Delay;
 use embedded_hal_bus::spi::ExclusiveDevice;
 use lora_phy::iv::GenericSx126xInterfaceVariant;
-use lora_phy::sx126x::{Sx126xVariant, TcxoCtrlVoltage, Sx126x};
+use lora_phy::sx126x::{Sx126x, Sx126xVariant, TcxoCtrlVoltage};
 use lora_phy::LoRa;
 use lora_phy::{mod_params::*, sx126x};
 use {defmt_rtt as _, panic_probe as _};