fw: add relay on pb9

fw/build.sh

@@ -1,3 +1,4 @@
+set -e -x
 cd cross
 cargo build --release
 llvm-objcopy -O binary ../target/riscv32imac-unknown-none-elf/release/cross ../firmware.bin

fw/cross/src/main.rs

@@ -51,6 +51,10 @@ fn main() -> ! {
     g.set_high().unwrap();
     b.set_high().unwrap();
 
+    // Relay output.
+    let mut relay = gpiob.pb9.into_push_pull_output();
+    relay.set_low().unwrap();
+
     // Set up LCD.
     let lcd_pins = lcd_pins!(gpioa, gpiob);
     let mut lcd = lcd::configure(dp.SPI0, lcd_pins, &mut afio, &mut rcu);
@@ -121,10 +125,14 @@ fn main() -> ! {
             ui::Transition::Running { .. } => {
                 s = &mut state_running;
                 s.enter(next);
+                // Jank.
+                relay.set_high().unwrap();
             },
             ui::Transition::TimeSelect => {
                 s = &mut state_ts;
                 s.enter(next);
+                // Jank.
+                relay.set_low().unwrap();
             },
         }
     }