Merge pull request #330 from quartiq/rs/issue-264/pounder-acr-write

Fixing ACR write padding

ad9959/src/lib.rs

@@ -558,13 +558,15 @@ impl ProfileSerializer {
     /// * `channels` - A list of channels to apply the configuration to.
     /// * `ftw` - If provided, indicates a frequency tuning word for the channels.
     /// * `pow` - If provided, indicates a phase offset word for the channels.
-    /// * `acr` - If provided, indicates the amplitude control register for the channels.
+    /// * `acr` - If provided, indicates the amplitude control register for the channels. The ACR
+    ///   should be stored in the 3 LSB of the word. Note that if amplitude scaling is to be used,
+    ///   the "Amplitude multiplier enable" bit must be set.
     pub fn update_channels(
         &mut self,
         channels: &[Channel],
         ftw: Option<u32>,
         pow: Option<u16>,
-        acr: Option<u16>,
+        acr: Option<u32>,
     ) {
         let mut csr: u8 = *0u8.set_bits(1..3, self.mode as u8);
         for channel in channels.iter() {
@@ -582,7 +584,7 @@ impl ProfileSerializer {
         }
 
         if let Some(acr) = acr {
-            self.add_write(Register::ACR, &acr.to_be_bytes());
+            self.add_write(Register::ACR, &acr.to_be_bytes()[1..=3]);
         }
     }
 
@@ -606,14 +608,14 @@ impl ProfileSerializer {
         // Pad the buffer to 32-bit alignment by adding dummy writes to CSR and LSRR.
         let padding = 4 - (self.index % 4);
         match padding {
-            0 => {}
             1 => {
                 // For a pad size of 1, we have to pad with 5 bytes to align things.
                 self.add_write(Register::CSR, &[(self.mode as u8) << 1]);
-                self.add_write(Register::LSRR, &[0, 0, 0]);
+                self.add_write(Register::LSRR, &[0, 0]);
             }
             2 => self.add_write(Register::CSR, &[(self.mode as u8) << 1]),
-            3 => self.add_write(Register::LSRR, &[0, 0, 0]),
+            3 => self.add_write(Register::LSRR, &[0, 0]),
+            4 => {}
 
             _ => unreachable!(),
         }

src/hardware/pounder/dds_output.rs

@@ -144,14 +144,15 @@ impl<'a> ProfileBuilder<'a> {
     /// * `channels` - A list of channels to apply the configuration to.
     /// * `ftw` - If provided, indicates a frequency tuning word for the channels.
     /// * `pow` - If provided, indicates a phase offset word for the channels.
-    /// * `acr` - If provided, indicates the amplitude control register for the channels.
+    /// * `acr` - If provided, indicates the amplitude control register for the channels. The
+    ///   24-bits of the ACR should be stored in the last 3 LSB.
     #[allow(dead_code)]
     pub fn update_channels(
         mut self,
         channels: &[Channel],
         ftw: Option<u32>,
         pow: Option<u16>,
-        acr: Option<u16>,
+        acr: Option<u32>,
     ) -> Self {
         self.serializer.update_channels(channels, ftw, pow, acr);
         self