diff --git a/src/runtime/src/main.rs b/src/runtime/src/main.rs
index dd24e25..252cff1 100644
--- a/src/runtime/src/main.rs
+++ b/src/runtime/src/main.rs
@@ -17,7 +17,7 @@ use libasync::task;
 use libboard_artiq::drtio_eem;
 #[cfg(feature = "target_kasli_soc")]
 use libboard_artiq::io_expander;
-use libboard_artiq::{identifier_read, logger, pl};
+use libboard_artiq::{cxp_downconn, cxp_proto, cxp_upconn, identifier_read, logger, pl};
 use libboard_zynq::{gic, mpcore, timer::GlobalTimer};
 use libconfig::Config;
 use libcortex_a9::l2c::enable_l2_cache;
@@ -150,5 +150,19 @@ pub fn main_core0() {
 
     task::spawn(ksupport::report_async_rtio_errors());
 
+    cxp_downconn::setup(&mut timer);
+    // cxp_downconn::loopback_testing(0, &mut timer, cxp_downconn::CXP_SPEED::CXP_1);
+    // cxp_downconn::loopback_testing(0, &mut timer, cxp_downconn::CXP_SPEED::CXP_2);
+    // cxp_downconn::loopback_testing(0, &mut timer, cxp_downconn::CXP_SPEED::CXP_3);
+    // cxp_downconn::loopback_testing(0, &mut timer, cxp_downconn::CXP_SPEED::CXP_5);
+    // cxp_downconn::loopback_testing(0, &mut timer, cxp_downconn::CXP_SPEED::CXP_6);
+    // cxp_downconn::loopback_testing(0, &mut timer, cxp_downconn::CXP_SPEED::CXP_10);
+    // cxp_downconn::loopback_testing(0, &mut timer, cxp_downconn::CXP_SPEED::CXP_12);
+    loop {
+        use embedded_hal::prelude::_embedded_hal_blocking_delay_DelayUs;
+        cxp_upconn::tx_test(0, &mut timer);
+        timer.delay_us(5_000_000);
+    }
+
     comms::main(timer, cfg);
 }