diff --git a/artiq/firmware/libboard_artiq/ad9154.rs b/artiq/firmware/libboard_artiq/ad9154.rs
index 9cd40b169..2f9bbd86c 100644
--- a/artiq/firmware/libboard_artiq/ad9154.rs
+++ b/artiq/firmware/libboard_artiq/ad9154.rs
@@ -1,5 +1,6 @@
 use board::{csr, clock};
 use ad9154_reg;
+use hmc830_7043::{hmc7043};
 
 fn spi_setup(dacno: u8) {
     unsafe {
@@ -607,6 +608,44 @@ fn dac_cfg_retry(dacno: u8) -> Result<(), &'static str> {
     dac_cfg(dacno)
 }
 
+fn dac_sysref_cfg(dacno: u8) {
+    let mut sync_error: u16 = 0;
+    let mut sync_error_last: u16 = 0;
+    let mut cphase_min_found: bool = false;
+    let mut cphase_min: u8 = 0;
+    let mut cphase_max_found: bool = false;
+    let mut cphase_max: u8 = 0;
+    let mut cphase_opt: u8 = 0;
+
+    info!("AD9154-{} SYSREF scan/conf...", dacno);
+    for cphase in 0..32 {
+        hmc7043::cfg_dac_sysref(dacno, 0, cphase);
+        clock::spin_us(10000);
+        spi_setup(dacno);
+        sync_error = ((read(ad9154_reg::SYNC_CURRERR_L) as u16) |
+                     ((read(ad9154_reg::SYNC_CURRERR_H) as u16) << 8))
+                     & 0x1ff;
+        info!("  cphase: {}, sync error: {}", cphase, sync_error);
+        if sync_error != 0 {
+            if cphase_min_found {
+                if sync_error != sync_error_last {
+                    cphase_max_found = true;
+                    cphase_max = cphase - 1;
+                    break;
+                }
+            } else {
+                cphase_min_found = true;
+                cphase_min = cphase;
+            }
+        }
+        sync_error_last = sync_error;
+    }
+
+    cphase_opt = cphase_min + (cphase_max-cphase_min)/2;
+    info!("  cphase min: {}, cphase max: {}, cphase opt: {}", cphase_min, cphase_max, cphase_opt);
+    hmc7043::cfg_dac_sysref(dacno, 0, cphase_opt);
+}
+
 pub fn init() -> Result<(), &'static str> {
     // Release the JESD clock domain reset late, as we need to
     // set up clock chips before.
@@ -617,6 +656,7 @@ pub fn init() -> Result<(), &'static str> {
         debug!("setting up AD9154-{} DAC...", dacno);
         dac_cfg_retry(dacno)?;
         dac_prbs(dacno)?;
+        dac_sysref_cfg(dacno);
         dac_cfg_retry(dacno)?;
     }
 
diff --git a/artiq/firmware/libboard_artiq/hmc830_7043.rs b/artiq/firmware/libboard_artiq/hmc830_7043.rs
index 44bf0f967..b1e5d9201 100644
--- a/artiq/firmware/libboard_artiq/hmc830_7043.rs
+++ b/artiq/firmware/libboard_artiq/hmc830_7043.rs
@@ -124,7 +124,7 @@ mod hmc830 {
     }
 }
 
-mod hmc7043 {
+pub mod hmc7043 {
     use board::csr;
 
     // To do: check which output channels we actually need
@@ -249,6 +249,20 @@ mod hmc7043 {
 
         Ok(())
     }
+
+    pub fn cfg_dac_sysref(dacno: u8, aphase: u8, cphase: u8) {
+        spi_setup();
+        if dacno == 0 {
+            write(0x00D5, aphase);
+            write(0x00D6, cphase);
+        } else if dacno == 1 {
+            write(0x00E9, aphase);
+            write(0x00EA, cphase);
+        } else {
+            unimplemented!();
+        }
+    }
+
 }
 
 pub fn init() -> Result<(), &'static str> {