diff --git a/artiq/firmware/libboard_artiq/ad9154.rs b/artiq/firmware/libboard_artiq/ad9154.rs
index 978f2a199..87aa8e29f 100644
--- a/artiq/firmware/libboard_artiq/ad9154.rs
+++ b/artiq/firmware/libboard_artiq/ad9154.rs
@@ -371,27 +371,9 @@ fn dac_setup(dacno: u8, linerate: u64) -> Result<(), &'static str> {
     write(ad9154_reg::LMFC_VAR_1, 0x0a);
     write(ad9154_reg::SYNC_ERRWINDOW, 0); // +- 1/2 DAC clock
     write(ad9154_reg::SYNC_CONTROL,
-            0x9*ad9154_reg::SYNCMODE | 0*ad9154_reg::SYNCENABLE |
-            0*ad9154_reg::SYNCARM | 1*ad9154_reg::SYNCCLRSTKY |
+            0x2*ad9154_reg::SYNCMODE | 1*ad9154_reg::SYNCENABLE |
             1*ad9154_reg::SYNCCLRLAST);
-    write(ad9154_reg::SYNC_CONTROL,
-            0x9*ad9154_reg::SYNCMODE | 1*ad9154_reg::SYNCENABLE |
-            0*ad9154_reg::SYNCARM | 1*ad9154_reg::SYNCCLRSTKY |
-            1*ad9154_reg::SYNCCLRLAST);
-    write(ad9154_reg::SYNC_CONTROL,
-            0x9*ad9154_reg::SYNCMODE | 1*ad9154_reg::SYNCENABLE |
-            1*ad9154_reg::SYNCARM | 0*ad9154_reg::SYNCCLRSTKY |
-            0*ad9154_reg::SYNCCLRLAST);
-    clock::spin_us(1000); // ensure at least one sysref edge
-    if read(ad9154_reg::SYNC_CONTROL) & ad9154_reg::SYNCARM != 0 {
-        return Err("no sysref edge");
-    }
-    if read(ad9154_reg::SYNC_STATUS) & ad9154_reg::SYNC_LOCK == 0 {
-        return Err("no sync lock");
-    }
-    if read(ad9154_reg::SYNC_STATUS) & ad9154_reg::SYNC_WLIM != 0 {
-        return Err("sysref phase error");
-    }
+
     write(ad9154_reg::XBAR_LN_0_1,
             0*ad9154_reg::LOGICAL_LANE0_SRC | 1*ad9154_reg::LOGICAL_LANE1_SRC);
     write(ad9154_reg::XBAR_LN_2_3,
@@ -689,9 +671,12 @@ fn dac_cfg_retry(dacno: u8) -> Result<(), &'static str> {
 
 pub fn dac_get_sync_error(dacno: u8) -> u16 {
     spi_setup(dacno);
-    let sync_error = ((read(ad9154_reg::SYNC_CURRERR_L) as u16) |
-                     ((read(ad9154_reg::SYNC_CURRERR_H) as u16) << 8))
+    let sync_error = ((read(ad9154_reg::SYNC_LASTERR_L) as u16) |
+                     ((read(ad9154_reg::SYNC_LASTERR_H) as u16) << 8))
                      & 0x1ff;
+    write(ad9154_reg::SYNC_CONTROL,
+            0x2*ad9154_reg::SYNCMODE | 1*ad9154_reg::SYNCENABLE |
+            1*ad9154_reg::SYNCCLRLAST);
     sync_error
 }
 
diff --git a/artiq/firmware/libboard_artiq/jesd204sync.rs b/artiq/firmware/libboard_artiq/jesd204sync.rs
index 81cf72cac..4510de794 100644
--- a/artiq/firmware/libboard_artiq/jesd204sync.rs
+++ b/artiq/firmware/libboard_artiq/jesd204sync.rs
@@ -148,13 +148,13 @@ fn sysref_cal_dac(dacno: u8) -> Result<u16, &'static str> {
 
     hmc7043::sysref_offset_dac(dacno, d);
     clock::spin_us(10000);
-    let sync_error_last = ad9154::dac_get_sync_error(dacno);
+    ad9154::dac_get_sync_error(dacno);  // clear SYNC_LASTERR
 
     loop {
         hmc7043::sysref_offset_dac(dacno, d);
         clock::spin_us(10000);
         let sync_error = ad9154::dac_get_sync_error(dacno);
-        if sync_error != sync_error_last {
+        if sync_error != 0 {
             dmin = d;
             break;
         }
@@ -165,16 +165,16 @@ fn sysref_cal_dac(dacno: u8) -> Result<u16, &'static str> {
         }
     }
 
-    d += 5;  // get away from jitter
+    d += 17;  // get away from jitter
     hmc7043::sysref_offset_dac(dacno, d);
     clock::spin_us(10000);
-    let sync_error_last = ad9154::dac_get_sync_error(dacno);
+    ad9154::dac_get_sync_error(dacno);  // clear SYNC_LASTERR
 
     loop {
         hmc7043::sysref_offset_dac(dacno, d);
         clock::spin_us(10000);
         let sync_error = ad9154::dac_get_sync_error(dacno);
-        if sync_error != sync_error_last {
+        if sync_error != 0 {
             dmax = d;
             break;
         }
@@ -198,13 +198,13 @@ fn sysref_dac_align(dacno: u8, phase: u16) -> Result<(), &'static str> {
 
     hmc7043::sysref_offset_dac(dacno, phase);
     clock::spin_us(10000);
-    let sync_error_last = ad9154::dac_get_sync_error(dacno);
+    ad9154::dac_get_sync_error(dacno);  // clear SYNC_LASTERR
     for d in 0..128 {
         hmc7043::sysref_offset_dac(dacno, phase - d);
         clock::spin_us(10000);
         let sync_error = ad9154::dac_get_sync_error(dacno);
-        if sync_error != sync_error_last {
-            info!("  sync error-: {} -> {}", sync_error_last, sync_error);
+        if sync_error != 0 {
+            info!("  sync error-: {}", sync_error);
             margin_minus = Some(d);
             break;
         }
@@ -212,13 +212,13 @@ fn sysref_dac_align(dacno: u8, phase: u16) -> Result<(), &'static str> {
 
     hmc7043::sysref_offset_dac(dacno, phase);
     clock::spin_us(10000);
-    let sync_error_last = ad9154::dac_get_sync_error(dacno);
+    ad9154::dac_get_sync_error(dacno);  // clear SYNC_LASTERR
     for d in 0..128 {
         hmc7043::sysref_offset_dac(dacno, phase + d);
         clock::spin_us(10000);
         let sync_error = ad9154::dac_get_sync_error(dacno);
-        if sync_error != sync_error_last {
-            info!("  sync error+: {} -> {}", sync_error_last, sync_error);
+        if sync_error != 0 {
+            info!("  sync error+: {}", sync_error);
             margin_plus = Some(d);
             break;
         }