sayma: automated DAC SYSREF phase calibration

artiq/firmware/libboard_artiq/ad9154.rs

@@ -1,6 +1,5 @@
 use board_misoc::{csr, clock};
 use ad9154_reg;
-use hmc830_7043::hmc7043;
 
 fn spi_setup(dacno: u8) {
     unsafe {
@@ -688,7 +687,7 @@ fn dac_cfg_retry(dacno: u8) -> Result<(), &'static str> {
     }
 }
 
-fn dac_get_sync_error(dacno: u8) -> u16 {
+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))
@@ -696,73 +695,24 @@ fn dac_get_sync_error(dacno: u8) -> u16 {
     sync_error
 }
 
-fn dac_sysref_scan(dacno: u8, center_phase: u16) {
-    let mut margin_minus = None;
-    let mut margin_plus = None;
-
-    info!("AD9154-{} SYSREF scan...", dacno);
-
-    hmc7043::sysref_offset_dac(dacno, center_phase);
-    clock::spin_us(10000);
-    let mut sync_error_last = dac_get_sync_error(dacno);
-    for d in 0..128 {
-        hmc7043::sysref_offset_dac(dacno, center_phase - d);
-        clock::spin_us(10000);
-        let sync_error = dac_get_sync_error(dacno);
-        if sync_error != sync_error_last {
-            info!("  sync error-: {} -> {}", sync_error_last, sync_error);
-            margin_minus = Some(d);
-            break;
-        }
-    }
-
-    hmc7043::sysref_offset_dac(dacno, center_phase);
-    clock::spin_us(10000);
-    sync_error_last = dac_get_sync_error(dacno);
-    for d in 0..128 {
-        hmc7043::sysref_offset_dac(dacno, center_phase + d);
-        clock::spin_us(10000);
-        let sync_error = dac_get_sync_error(dacno);
-        if sync_error != sync_error_last {
-            info!("  sync error+: {} -> {}", sync_error_last, sync_error);
-            margin_plus = Some(d);
-            break;
-        }
-    }
-
-    if margin_minus.is_some() && margin_plus.is_some() {
-        let margin_minus = margin_minus.unwrap();
-        let margin_plus = margin_plus.unwrap();
-        info!("  margins: -{} +{}", margin_minus, margin_plus);
-        if margin_minus < 10 || margin_plus < 10 {
-            error!("SYSREF margins are too small");
-        }
-    } else {
-        error!("Unable to determine SYSREF margins");
-    }
-}
-
-fn init_dac(dacno: u8, sysref_phase: u16) -> Result<(), &'static str> {
+fn init_dac(dacno: u8) -> Result<(), &'static str> {
     let dacno = dacno as u8;
-    // Reset the DAC, detect and configure it
+
     dac_reset(dacno);
     dac_detect(dacno)?;
     dac_cfg_retry(dacno)?;
-    // Run the PRBS, STPL and SYSREF scan tests
+
     dac_prbs(dacno)?;
     dac_stpl(dacno, 4, 2)?;
-    dac_sysref_scan(dacno, sysref_phase);
-    // Set SYSREF phase and reconfigure the DAC
-    hmc7043::sysref_offset_dac(dacno, sysref_phase);
+
     dac_cfg_retry(dacno)?;
+
     Ok(())
 }
 
-pub fn init(sysref_phase_dac: u16) {
+pub fn init() {
     for dacno in 0..csr::AD9154.len() {
-        // We assume DCLK and SYSREF traces are matched on the PCB
-        // (they are on Sayma) so only one phase is needed.
-        match init_dac(dacno as u8, sysref_phase_dac) {
+        match init_dac(dacno as u8) {
             Ok(_) => (),
             Err(e) => error!("failed to initialize AD9154-{}: {}", dacno, e)
         }

artiq/firmware/libboard_artiq/jesd204sync.rs

@@ -1,8 +1,7 @@
-use board_misoc::csr;
-use board_misoc::config;
+use board_misoc::{csr, clock, config};
 
 use hmc830_7043::hmc7043;
-
+use ad9154;
 
 fn sysref_sample() -> bool {
     unsafe { csr::sysref_sampler::sample_result_read() == 1 }
@@ -142,3 +141,127 @@ pub fn sysref_auto_rtio_align(expected_align: u16) -> Result<(), &'static str> {
     };
     sysref_rtio_align(phase_offset, expected_align)
 }
+
+fn sysref_cal_dac(dacno: u8) -> Result<u16, &'static str> {
+    info!("calibrating SYSREF phase at DAC-{}...", dacno);
+
+    let mut d = 0;
+    let dmin;
+    let dmax;
+
+    hmc7043::sysref_offset_dac(dacno, d);
+    clock::spin_us(10000);
+    let sync_error_last = ad9154::dac_get_sync_error(dacno);
+
+    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 {
+            dmin = d;
+            break;
+        }
+
+        d += 1;
+        if d > 128 {
+            return Err("no sync errors found when scanning delay");
+        }
+    }
+
+    d += 5;  // get away from jitter
+    hmc7043::sysref_offset_dac(dacno, d);
+    clock::spin_us(10000);
+    let sync_error_last = ad9154::dac_get_sync_error(dacno);
+
+    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 {
+            dmax = d;
+            break;
+        }
+
+        d += 1;
+        if d > 128 {
+            return Err("no sync errors found when scanning delay");
+        }
+    }
+
+    let phase = (dmin+dmax)/2;
+    info!("  ...done, min={}, max={}, result={}", dmin, dmax, phase);
+    Ok(phase)
+}
+
+fn sysref_dac_align(dacno: u8, phase: u16) -> Result<(), &'static str> {
+    let mut margin_minus = None;
+    let mut margin_plus = None;
+
+    info!("verifying SYSREF margins at DAC-{}...", dacno);
+
+    hmc7043::sysref_offset_dac(dacno, phase);
+    clock::spin_us(10000);
+    let sync_error_last = ad9154::dac_get_sync_error(dacno);
+    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);
+            margin_minus = Some(d);
+            break;
+        }
+    }
+
+    hmc7043::sysref_offset_dac(dacno, phase);
+    clock::spin_us(10000);
+    let sync_error_last = ad9154::dac_get_sync_error(dacno);
+    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);
+            margin_plus = Some(d);
+            break;
+        }
+    }
+
+    if margin_minus.is_some() && margin_plus.is_some() {
+        let margin_minus = margin_minus.unwrap();
+        let margin_plus = margin_plus.unwrap();
+        info!("  margins: -{} +{}", margin_minus, margin_plus);
+        if margin_minus < 10 || margin_plus < 10 {
+            return Err("SYSREF margins at DAC are too small, board needs recalibration");
+        }
+    } else {
+        return Err("Unable to determine SYSREF margins at DAC");
+    }
+
+    // Leave SYSREF at the correct setting
+    hmc7043::sysref_offset_dac(dacno, phase);
+
+    Ok(())
+}
+
+pub fn sysref_auto_dac_align() -> Result<(), &'static str> {
+    // We assume that DAC SYSREF traces are length-matched so only one phase
+    // value is needed, and we use DAC-0 as calibration reference.
+
+    let entry = config::read_str("sysref_phase_dac", |r| r.map(|s| s.parse()));
+    let phase = match entry {
+        Ok(Ok(phase)) => phase,
+        _ => {
+            let phase = sysref_cal_dac(0)?;
+            if let Err(e) = config::write_int("sysref_phase_dac", phase as u32) {
+                error!("failed to update DAC SYSREF phase in config: {}", e);
+            }
+            phase
+        }
+    };
+
+    for dacno in 0..csr::AD9154.len() {
+        sysref_dac_align(dacno as u8, phase)?;
+    }
+    Ok(())
+}

artiq/firmware/runtime/main.rs

@@ -56,9 +56,6 @@ mod moninj;
 #[cfg(has_rtio_analyzer)]
 mod analyzer;
 
-#[cfg(has_ad9154)]
-const SYSREF_PHASE_DAC: u16 = 94;
-
 fn startup() {
     irq::set_mask(0);
     irq::set_ie(true);
@@ -114,10 +111,13 @@ fn startup() {
     #[cfg(has_ad9154)]
     {
         board_artiq::ad9154::jesd_unreset();
+        board_artiq::ad9154::init();
         if let Err(e) = board_artiq::jesd204sync::sysref_auto_rtio_align(1) {
             error!("failed to align SYSREF at FPGA: {}", e);
         }
-        board_artiq::ad9154::init(SYSREF_PHASE_DAC);
+        if let Err(e) = board_artiq::jesd204sync::sysref_auto_dac_align() {
+            error!("failed to align SYSREF at DAC: {}", e);
+        }
     }
     #[cfg(has_allaki_atts)]
     board_artiq::hmc542::program_all(8/*=4dB*/);