feat(embedded-hal-bus): Spi - Add support for cs to clock delay

Author: vchapuis

embedded-hal-bus/src/spi/atomic.rs

@@ -30,6 +30,9 @@ pub struct AtomicDevice<'a, BUS, CS, D> {
     bus: &'a AtomicCell<BUS>,
     cs: CS,
     delay: D,
+    /// Implementation of <https://docs.rs/embedded-hal/latest/embedded_hal/spi/index.html#cs-to-clock-delays>
+    cs_to_clock_delay_ns: u32,
+    clock_to_cs_delay_ns: u32,
 }
 
 #[derive(Debug, Copy, Clone)]
@@ -55,7 +58,23 @@ impl<'a, BUS, CS, D> AtomicDevice<'a, BUS, CS, D> {
         CS: OutputPin,
     {
         cs.set_high()?;
-        Ok(Self { bus, cs, delay })
+        Ok(Self {
+            bus,
+            cs,
+            delay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
+        })
+    }
+
+    /// Set the delay between the CS pin toggle and the first clock
+    pub fn set_cs_to_clock_delay_ns(&mut self, delay_ns: u32) {
+        self.cs_to_clock_delay_ns = delay_ns;
+    }
+
+    /// Set the delay between the last clock and the CS pin reset
+    pub fn set_clock_to_cs_delay_ns(&mut self, delay_ns: u32) {
+        self.clock_to_cs_delay_ns = delay_ns;
     }
 }
 
@@ -93,6 +112,8 @@ where
             bus,
             cs,
             delay: super::NoDelay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
         })
     }
 }
@@ -134,7 +155,14 @@ where
 
         let bus = unsafe { &mut *self.bus.bus.get() };
 
-        let result = transaction(operations, bus, &mut self.delay, &mut self.cs);
+        let result = transaction(
+            operations,
+            bus,
+            &mut self.delay,
+            &mut self.cs,
+            self.cs_to_clock_delay_ns,
+            self.clock_to_cs_delay_ns,
+        );
 
         self.bus
             .busy

embedded-hal-bus/src/spi/critical_section.rs

@@ -21,6 +21,9 @@ pub struct CriticalSectionDevice<'a, BUS, CS, D> {
     bus: &'a Mutex<RefCell<BUS>>,
     cs: CS,
     delay: D,
+    /// Implementation of <https://docs.rs/embedded-hal/latest/embedded_hal/spi/index.html#cs-to-clock-delays>
+    cs_to_clock_delay_ns: u32,
+    clock_to_cs_delay_ns: u32,
 }
 
 impl<'a, BUS, CS, D> CriticalSectionDevice<'a, BUS, CS, D> {
@@ -34,7 +37,23 @@ impl<'a, BUS, CS, D> CriticalSectionDevice<'a, BUS, CS, D> {
         CS: OutputPin,
     {
         cs.set_high()?;
-        Ok(Self { bus, cs, delay })
+        Ok(Self {
+            bus,
+            cs,
+            delay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
+        })
+    }
+
+    /// Set the delay between the CS pin toggle and the first clock
+    pub fn set_cs_to_clock_delay_ns(&mut self, delay_ns: u32) {
+        self.cs_to_clock_delay_ns = delay_ns;
+    }
+
+    /// Set the delay between the last clock and the CS pin reset
+    pub fn set_clock_to_cs_delay_ns(&mut self, delay_ns: u32) {
+        self.clock_to_cs_delay_ns = delay_ns;
     }
 }
 
@@ -68,6 +87,8 @@ impl<'a, BUS, CS> CriticalSectionDevice<'a, BUS, CS, super::NoDelay> {
             bus,
             cs,
             delay: super::NoDelay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
         })
     }
 }
@@ -91,7 +112,14 @@ where
         critical_section::with(|cs| {
             let bus = &mut *self.bus.borrow_ref_mut(cs);
 
-            transaction(operations, bus, &mut self.delay, &mut self.cs)
+            transaction(
+                operations,
+                bus,
+                &mut self.delay,
+                &mut self.cs,
+                self.cs_to_clock_delay_ns,
+                self.clock_to_cs_delay_ns,
+            )
         })
     }
 }

embedded-hal-bus/src/spi/exclusive.rs

@@ -20,6 +20,9 @@ pub struct ExclusiveDevice<BUS, CS, D> {
     bus: BUS,
     cs: CS,
     delay: D,
+    /// Implementation of <https://docs.rs/embedded-hal/latest/embedded_hal/spi/index.html#cs-to-clock-delays>
+    cs_to_clock_delay_ns: u32,
+    clock_to_cs_delay_ns: u32,
 }
 
 impl<BUS, CS, D> ExclusiveDevice<BUS, CS, D> {
@@ -33,7 +36,23 @@ impl<BUS, CS, D> ExclusiveDevice<BUS, CS, D> {
         CS: OutputPin,
     {
         cs.set_high()?;
-        Ok(Self { bus, cs, delay })
+        Ok(Self {
+            bus,
+            cs,
+            delay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
+        })
+    }
+
+    /// Set the delay between the CS pin toggle and the first clock
+    pub fn set_cs_to_clock_delay_ns(&mut self, delay_ns: u32) {
+        self.cs_to_clock_delay_ns = delay_ns;
+    }
+
+    /// Set the delay between the last clock and the CS pin reset
+    pub fn set_clock_to_cs_delay_ns(&mut self, delay_ns: u32) {
+        self.clock_to_cs_delay_ns = delay_ns;
     }
 
     /// Returns a reference to the underlying bus object.
@@ -79,6 +98,8 @@ impl<BUS, CS> ExclusiveDevice<BUS, CS, super::NoDelay> {
             bus,
             cs,
             delay: super::NoDelay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
         })
     }
 }
@@ -99,7 +120,14 @@ where
 {
     #[inline]
     fn transaction(&mut self, operations: &mut [Operation<'_, Word>]) -> Result<(), Self::Error> {
-        transaction(operations, &mut self.bus, &mut self.delay, &mut self.cs)
+        transaction(
+            operations,
+            &mut self.bus,
+            &mut self.delay,
+            &mut self.cs,
+            self.cs_to_clock_delay_ns,
+            self.clock_to_cs_delay_ns,
+        )
     }
 }
 

embedded-hal-bus/src/spi/mutex.rs

@@ -19,6 +19,9 @@ pub struct MutexDevice<'a, BUS, CS, D> {
     bus: &'a Mutex<BUS>,
     cs: CS,
     delay: D,
+    /// Implementation of <https://docs.rs/embedded-hal/latest/embedded_hal/spi/index.html#cs-to-clock-delays>
+    cs_to_clock_delay_ns: u32,
+    clock_to_cs_delay_ns: u32,
 }
 
 impl<'a, BUS, CS, D> MutexDevice<'a, BUS, CS, D> {
@@ -32,7 +35,23 @@ impl<'a, BUS, CS, D> MutexDevice<'a, BUS, CS, D> {
         CS: OutputPin,
     {
         cs.set_high()?;
-        Ok(Self { bus, cs, delay })
+        Ok(Self {
+            bus,
+            cs,
+            delay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
+        })
+    }
+
+    /// Set the delay between the CS pin toggle and the first clock
+    pub fn set_cs_to_clock_delay_ns(&mut self, delay_ns: u32) {
+        self.cs_to_clock_delay_ns = delay_ns;
+    }
+
+    /// Set the delay between the last clock and the CS pin reset
+    pub fn set_clock_to_cs_delay_ns(&mut self, delay_ns: u32) {
+        self.clock_to_cs_delay_ns = delay_ns;
     }
 }
 
@@ -66,6 +85,8 @@ impl<'a, BUS, CS> MutexDevice<'a, BUS, CS, super::NoDelay> {
             bus,
             cs,
             delay: super::NoDelay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
         })
     }
 }
@@ -88,6 +109,13 @@ where
     fn transaction(&mut self, operations: &mut [Operation<'_, Word>]) -> Result<(), Self::Error> {
         let bus = &mut *self.bus.lock().unwrap();
 
-        transaction(operations, bus, &mut self.delay, &mut self.cs)
+        transaction(
+            operations,
+            bus,
+            &mut self.delay,
+            &mut self.cs,
+            self.cs_to_clock_delay_ns,
+            self.clock_to_cs_delay_ns,
+        )
     }
 }

embedded-hal-bus/src/spi/refcell.rs

@@ -18,6 +18,9 @@ pub struct RefCellDevice<'a, BUS, CS, D> {
     bus: &'a RefCell<BUS>,
     cs: CS,
     delay: D,
+    /// Implementation of <https://docs.rs/embedded-hal/latest/embedded_hal/spi/index.html#cs-to-clock-delays>
+    cs_to_clock_delay_ns: u32,
+    clock_to_cs_delay_ns: u32,
 }
 
 impl<'a, BUS, CS, D> RefCellDevice<'a, BUS, CS, D> {
@@ -31,7 +34,23 @@ impl<'a, BUS, CS, D> RefCellDevice<'a, BUS, CS, D> {
         CS: OutputPin,
     {
         cs.set_high()?;
-        Ok(Self { bus, cs, delay })
+        Ok(Self {
+            bus,
+            cs,
+            delay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
+        })
+    }
+
+    /// Set the delay between the CS pin toggle and the first clock
+    pub fn set_cs_to_clock_delay_ns(&mut self, delay_ns: u32) {
+        self.cs_to_clock_delay_ns = delay_ns;
+    }
+
+    /// Set the delay between the last clock and the CS pin reset
+    pub fn set_clock_to_cs_delay_ns(&mut self, delay_ns: u32) {
+        self.clock_to_cs_delay_ns = delay_ns;
     }
 }
 
@@ -65,6 +84,8 @@ impl<'a, BUS, CS> RefCellDevice<'a, BUS, CS, super::NoDelay> {
             bus,
             cs,
             delay: super::NoDelay,
+            cs_to_clock_delay_ns: 0,
+            clock_to_cs_delay_ns: 0,
         })
     }
 }
@@ -87,6 +108,13 @@ where
     fn transaction(&mut self, operations: &mut [Operation<'_, Word>]) -> Result<(), Self::Error> {
         let bus = &mut *self.bus.borrow_mut();
 
-        transaction(operations, bus, &mut self.delay, &mut self.cs)
+        transaction(
+            operations,
+            bus,
+            &mut self.delay,
+            &mut self.cs,
+            self.cs_to_clock_delay_ns,
+            self.clock_to_cs_delay_ns,
+        )
     }
 }

embedded-hal-bus/src/spi/shared.rs

@@ -11,6 +11,8 @@ pub fn transaction<Word, BUS, CS, D>(
     bus: &mut BUS,
     delay: &mut D,
     cs: &mut CS,
+    cs_to_clock_delay_ns: u32,
+    clock_to_cs_delay_ns: u32,
 ) -> Result<(), DeviceError<BUS::Error, CS::Error>>
 where
     BUS: SpiBus<Word> + ErrorType,
@@ -19,6 +21,9 @@ where
     Word: Copy,
 {
     cs.set_low().map_err(DeviceError::Cs)?;
+    if cs_to_clock_delay_ns > 0 {
+        delay.delay_ns(cs_to_clock_delay_ns);
+    }
 
     let op_res = operations.iter_mut().try_for_each(|op| match op {
         Operation::Read(buf) => bus.read(buf),
@@ -34,6 +39,9 @@ where
 
     // On failure, it's important to still flush and deassert CS.
     let flush_res = bus.flush();
+    if clock_to_cs_delay_ns > 0 {
+        delay.delay_ns(cs_to_clock_delay_ns);
+    }
     let cs_res = cs.set_high();
 
     op_res.map_err(DeviceError::Spi)?;