From d012fd155338641f1d54d68d04410a848e07319d Mon Sep 17 00:00:00 2001
From: Scott Shawcroft <scott@tannewt.org>
Date: Fri, 9 Nov 2018 17:06:55 -0800
Subject: [PATCH] Only write to usb when its around.

---
 supervisor/shared/serial.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/supervisor/shared/serial.c b/supervisor/shared/serial.c
index cd20b5c26e..c57688ddcf 100644
--- a/supervisor/shared/serial.c
+++ b/supervisor/shared/serial.c
@@ -48,6 +48,9 @@ bool serial_bytes_available(void) {
 }
 
 void serial_write_substring(const char* text, uint32_t length) {
+    if (!tud_cdc_connected()) {
+        return;
+    }
     uint32_t count = 0;
     while (count < length) {
         count += tud_cdc_write(text + count, length - count);