sprinkle some delays to fix failures in optimized builds

Author: japaric

nrf52840-hal-tests/Cargo.toml

@@ -25,6 +25,7 @@ name = "serial"
 harness = false
 
 [dev-dependencies]
+cortex-m = "0.7.0"
 defmt = "0.1.3"
 defmt-rtt = "0.1.0"
 defmt-test = "0.1.1"

nrf52840-hal-tests/tests/gpio-input-pull.rs

@@ -19,6 +19,7 @@ struct State {
 
 #[defmt_test::tests]
 mod tests {
+    use cortex_m::asm;
     use defmt::{assert, unwrap};
     use nrf52840_hal::{gpio::p0, pac, prelude::*};
 
@@ -53,6 +54,8 @@ mod tests {
         let pull_pin = unwrap!(state.pull_pin.take());
 
         let pullup_pin = pull_pin.into_pullup_input();
+        // GPIO re-configuration is not instantaneous so a delay is needed
+        asm::delay(100);
         assert!(state.input_pin.is_high().unwrap());
 
         state.pull_pin = Some(pullup_pin.into_floating_input());

nrf52840-hal-tests/tests/gpio-output-push-pull.rs

@@ -19,6 +19,7 @@ struct State {
 
 #[defmt_test::tests]
 mod tests {
+    use cortex_m::asm;
     use defmt::{assert, unwrap};
     use nrf52840_hal::{
         gpio::{p0, Level},
@@ -45,12 +46,16 @@ mod tests {
     #[test]
     fn set_low_is_low(state: &mut State) {
         state.output_pin.set_low().unwrap();
+        // GPIO operations are not instantaneous so a delay is needed
+        asm::delay(100);
         assert!(state.input_pin.is_low().unwrap());
     }
 
     #[test]
     fn set_high_is_high(state: &mut State) {
         state.output_pin.set_high().unwrap();
+        // GPIO operations are not instantaneous so a delay is needed
+        asm::delay(100);
         assert!(state.input_pin.is_high().unwrap());
     }
 }