diff --git a/libraries/AP_HAL_ChibiOS/hwdef/crazyflie2/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/crazyflie2/hwdef.dat
index ccf31c390e..e62c3401eb 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/crazyflie2/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/crazyflie2/hwdef.dat
@@ -20,8 +20,9 @@ FLASH_SIZE_KB 1024
 # board voltage
 STM32_VDD 330U
 
-STDOUT_SERIAL SD3
-STDOUT_BAUDRATE 57600
+# use USB for stdout
+#STDOUT_SERIAL SD3
+#STDOUT_BAUDRATE 57600
 
 # usart2
 PA2 USART2_TX USART2 # E_TX2
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/f4by-ch/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/f4by-ch/hwdef.dat
index 0a4da151cf..6c7f779122 100755
--- a/libraries/AP_HAL_ChibiOS/hwdef/f4by-ch/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/f4by-ch/hwdef.dat
@@ -45,14 +45,15 @@ PA14 JTCK-SWCLK SWD
 # 5) SERIAL4: GPS2
 # 6) SERIAL5: extra UART (usually RTOS debug console)
 
-STDOUT_SERIAL SD5
-STDOUT_BAUDRATE 57600
+# use UART for stdout, so no STDOUT_SERIAL
+#STDOUT_SERIAL SD5
+#STDOUT_BAUDRATE 57600
 
 # this is the pin that senses USB being connected. It is an input pin
 # setup as OPENDRAIN
 PA9 VBUS INPUT OPENDRAIN
 
-UART_ORDER OTG1 USART3 USART2 USART1 
+UART_ORDER OTG1 USART3 USART2 USART1 UART5
 
 # UART1 as board 2.1.5 for serial 3 gps
 PB6 USART1_TX USART1
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/mini-pix/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/mini-pix/hwdef.dat
index 910617d764..9fa4aff9e5 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/mini-pix/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/mini-pix/hwdef.dat
@@ -20,8 +20,9 @@ FLASH_SIZE_KB 1024
 # board voltage
 STM32_VDD 330U
 
-STDOUT_SERIAL SD2
-STDOUT_BAUDRATE 57600
+# use USB for stdout, so no STDOUT_SERIAL
+# STDOUT_SERIAL SD2
+# STDOUT_BAUDRATE 57600
 
 # only one I2C bus
 I2C_ORDER I2C2 I2C1
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/revo-mini/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/revo-mini/hwdef.dat
index 3b87ec81fe..aa5448f2e9 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/revo-mini/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/revo-mini/hwdef.dat
@@ -20,8 +20,9 @@ FLASH_SIZE_KB 1024
 # board voltage
 STM32_VDD 330U
 
-STDOUT_SERIAL SD3
-STDOUT_BAUDRATE 57600
+# use USB for stdout, so no STDOUT_SERIAL
+# STDOUT_SERIAL SD3
+# STDOUT_BAUDRATE 57600
 
 # only one I2C bus
 I2C_ORDER I2C1
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/sparky2/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/sparky2/hwdef.dat
index 3edbd39d49..af062ca64f 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/sparky2/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/sparky2/hwdef.dat
@@ -18,9 +18,9 @@ FLASH_SIZE_KB 1024
 # board voltage
 STM32_VDD 330U
 
-# serial port for stdout via flexi-port (conn3)
-STDOUT_SERIAL SD1
-STDOUT_BAUDRATE 115200
+# use USB for stdout, so no STDOUT_SERIAL
+# STDOUT_SERIAL SD1
+# STDOUT_BAUDRATE 115200
 
 # --------LEDs-----------
 PB5 LED_BLUE OUTPUT LOW GPIO(0)