diff --git a/src/raspi_keyer.cpp b/src/raspi_keyer.cpp
index 335d5ab..89a5b85 100644
--- a/src/raspi_keyer.cpp
+++ b/src/raspi_keyer.cpp
@@ -1,14 +1,14 @@
 #include <stdio.h>
 
+#include "bsp/board.h"
 #include "pico/multicore.h"
 #include "pico/stdlib.h"
 #include "pico/util/queue.h"
 #include "tusb.h"
-#include "bsp/board.h"
 
-#include "tusb_config.h"
 #include "keyer.h"
 #include "settings.h"
+#include "tusb_config.h"
 
 namespace
 {
@@ -89,6 +89,43 @@ void core1_main()
     }
 }
 
+[[maybe_unused]]
+static void echo_serial_port(uint8_t itf, uint8_t buf[], uint32_t count)
+{
+  for(uint32_t i=0; i<count; i++)
+  {
+    tud_cdc_n_write_char(itf, buf[i]);
+  }
+
+  tud_cdc_n_write_flush(itf);
+}
+
+void cdc_task()
+{
+    const uint8_t UsbInIf = 1;
+
+    if (tud_cdc_n_available(UsbInIf)) {
+        uint8_t buf[64];
+
+        uint32_t count = tud_cdc_n_read(UsbInIf, buf, sizeof(buf));
+        if (count > 1) {
+            printf("Command received …\n");
+            switch (buf[0]) {
+                case 0: // ADMIN COMMAND
+                switch (buf[1]) {
+                    case 2: // Host Open
+                    // TODO: send back revision code
+                    default:
+                    printf("Unknown admin command.\n");
+                }
+                break;
+            default:
+                printf("Unknown command.\n");
+            }
+        }
+    }
+}
+
 int main()
 {
     // timer_hw->dbgpause = 2; // workaround for problem with debug and sleep_ms
@@ -97,23 +134,22 @@ int main()
     setup();
     board_init();
     tud_init(BOARD_TUD_RHPORT);
- 
+
     printf("Hello from core0!\n");
 
-    Settings settings{read_settings()};
+    Settings settings {read_settings()};
     settings.wpm = 25; // TODO: remove!
 
     queue_init(&keyerQueue, sizeof(KeyerQueueData), 2);
     multicore_reset_core1();
     multicore_launch_core1(core1_main);
 
-    KeyerQueueData keyerQueueData{KeyerQueueCommand::Run, settings.wpm, settings.mode};
+    KeyerQueueData keyerQueueData {KeyerQueueCommand::Run, settings.wpm, settings.mode};
     queue_add_blocking(&keyerQueue, &keyerQueueData);
 
     while (true) {
-        // Currently there's nothing to do on core0
-        sleep_ms(1000);
         tud_task();
+        cdc_task();
     }
 
     return 0;