diff --git a/src/libboard_artiq/src/cxp_downconn.rs b/src/libboard_artiq/src/cxp_downconn.rs
index e8211b7..5b2bf59 100644
--- a/src/libboard_artiq/src/cxp_downconn.rs
+++ b/src/libboard_artiq/src/cxp_downconn.rs
@@ -37,36 +37,41 @@ pub fn loopback_testing(timer: &mut GlobalTimer, speed: CXP_SPEED) {
         while csr::cxp::downconn_phy_rx_ready_read() != 1 {}
         info!("rx ready!");
 
+        cxp_proto::downconn_debug_send_trig_ack();
+
         cxp_proto::downconn_debug_send(&cxp_proto::Packet::CtrlRead {
             addr: 0x00,
             length: 0x04,
         });
 
         timer.delay_us(200); // wait packet has arrive at async fifo in
-        unsafe {
-            csr::cxp::downconn_phy_tx_stb_write(1);
-            timer.delay_us(200);
-            csr::cxp::downconn_phy_tx_stb_write(0);
-        }
+        csr::cxp::downconn_phy_tx_stb_write(1);
+        timer.delay_us(200);
+        csr::cxp::downconn_phy_tx_stb_write(0);
+
+        info!("trig ack = {}", csr::cxp::downconn_trig_ack_read());
+        csr::cxp::downconn_trig_clr_write(1);
+        info!("after clr trig ack = {}", csr::cxp::downconn_trig_ack_read());
 
         // TODO: investigate how to make my packet appear
         // TODO: discard idle word
 
+        // DEBUG: print loopback packets
         const LEN: usize = 20;
         let mut pak_arr: [u32; LEN] = [0; LEN];
+        let mut k_arr: [u8; LEN] = [0; LEN];
         let mut i: usize = 0;
-        unsafe {
-            while csr::cxp::downconn_debug_out_dout_valid_read() == 1 {
-                pak_arr[i] = csr::cxp::downconn_debug_out_dout_pak_read();
-                // println!("received {:#04X}", pak_arr[i]);
-                csr::cxp::downconn_debug_out_inc_write(1);
-                i += 1;
-                if i == LEN {
-                    break;
-                }
+        while csr::cxp::downconn_debug_out_dout_valid_read() == 1 {
+            pak_arr[i] = csr::cxp::downconn_debug_out_dout_pak_read();
+            k_arr[i] = csr::cxp::downconn_debug_out_kout_pak_read();
+            // println!("received {:#04X}", pak_arr[i]);
+            csr::cxp::downconn_debug_out_inc_write(1);
+            i += 1;
+            if i == LEN {
+                break;
             }
         }
-        cxp_proto::print_packetu32(&pak_arr)
+        cxp_proto::print_packetu32(&pak_arr, &k_arr);
     }
 }