diff --git a/Tools/AP_Bootloader/board_types.txt b/Tools/AP_Bootloader/board_types.txt
index 16eda3f59e8dc..4fe8b8f21af4f 100644
--- a/Tools/AP_Bootloader/board_types.txt
+++ b/Tools/AP_Bootloader/board_types.txt
@@ -108,6 +108,7 @@ AP_HW_JDMINIF405                      144
 AP_HW_KAKUTEF7_MINI                   145
 AP_HW_H757I_EVAL                      146
 AP_HW_F4BY                             20 # value due to previous release by vendor
+AP_HW_F4BY_F427                        21
 AP_HW_MAZZYSTARDRONE                  188
 
 AP_HW_VRBRAIN_V51                    1151
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/README.md b/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/README.md
new file mode 100644
index 0000000000000..534e86b0c0600
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/README.md
@@ -0,0 +1,17 @@
+# F4BY Flight Controller MCU upgrade
+
+
+## Howto
+replace old MCU STM32F407VGT (1MB Flash) with STM32F427VET rev3 or above (2MB Flash)
+
+## Features
+
+ - Full Ardupilot features support (exclude LUA Script)
+
+
+## Loading Firmware
+
+Initial firmware load can be done with DFU by plugging in USB with the
+boot solder pads connected. Then you should load the "with_bl.hex"
+firmware, using your favourite DFU loading tool.
+
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/defaults.parm b/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/defaults.parm
new file mode 100644
index 0000000000000..f592805319c11
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/defaults.parm
@@ -0,0 +1,7 @@
+BATT_AMP_OFFSET 2.316
+BATT_AMP_PERVLT 100
+BATT_CURR_PIN 12
+BATT_MONITOR 4
+BATT_VLT_OFFSET 0
+BATT_VOLT_MULT 16.04981
+BATT_VOLT_PIN 13
\ No newline at end of file
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/hwdef-bl.dat b/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/hwdef-bl.dat
new file mode 100644
index 0000000000000..13e4600d86782
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/hwdef-bl.dat
@@ -0,0 +1,42 @@
+# hw definition file for processing by chibios_hwdef.py
+# for f4by bootloader
+
+MCU STM32F4xx STM32F427xx
+
+APJ_BOARD_ID 21
+
+OSCILLATOR_HZ 8000000
+
+STM32_ST_USE_TIMER 5
+
+# flash size
+FLASH_SIZE_KB 2048
+
+# order of UARTs (and USB)
+SERIAL_ORDER OTG1 USART2
+
+PE3 LED_BOOTLOADER OUTPUT
+PE2 LED_ACTIVITY OUTPUT
+define HAL_LED_ON 1
+
+PA9 VBUS INPUT
+
+PA11 OTG_FS_DM OTG1
+PA12 OTG_FS_DP OTG1
+
+PA13 JTMS-SWDIO SWD
+PA14 JTCK-SWCLK SWD
+
+PD5 USART2_TX USART2
+PD6 USART2_RX USART2
+
+FLASH_USE_MAX_KB 16
+FLASH_RESERVE_START_KB 0
+
+# location of application code
+FLASH_BOOTLOADER_LOAD_KB 16
+
+# Add CS pins to ensure they are high in bootloader
+PA4 MPU_CS CS
+PB12 FRAM_CS CS SPEED_VERYLOW
+PE15 FLASH_CS CS
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/hwdef.dat
new file mode 100644
index 0000000000000..9f612f46a2011
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/F4BY_F427/hwdef.dat
@@ -0,0 +1,169 @@
+# hw definition file for processing by chibios_hwdef.py
+# for F4BY v2.1.5 board description http://swift-flyer.com/?page_id=83
+
+# MCU class and specific type
+MCU STM32F4xx STM32F427xx
+
+# board ID for firmware load
+APJ_BOARD_ID 21
+
+# USB setup
+USB_VENDOR 0x27AC # Swift-Flyer
+USB_PRODUCT 0x0201 # fmu usb driver
+USB_STRING_MANUFACTURER "Swift-Flyer"
+PA11 OTG_FS_DM OTG1
+PA12 OTG_FS_DP OTG1
+# this is the pin that senses USB being connected. It is an input pin
+# setup as OPENDRAIN
+PA9 VBUS INPUT OPENDRAIN
+
+
+FLASH_SIZE_KB 2048
+FLASH_RESERVE_START_KB 16
+define HAL_STORAGE_SIZE 16384
+env OPTIMIZE -O2 
+
+# crystal frequency
+OSCILLATOR_HZ 8000000
+
+# ChibiOS system timer
+STM32_ST_USE_TIMER 5
+
+
+
+PA13 JTMS-SWDIO SWD
+PA14 JTCK-SWCLK SWD
+
+# the normal usage of this ordering is:
+# 1) SERIAL0: console (primary mavlink, usually USB)
+# 2) SERIAL3: primary GPS
+# 3) SERIAL1: telem1
+# 4) SERIAL2: telem2
+# 5) SERIAL4: GPS2
+# 6) SERIAL5: extra UART (usually RTOS debug console)
+
+# use UART for stdout, so no STDOUT_SERIAL
+#STDOUT_SERIAL SD5
+#STDOUT_BAUDRATE 57600
+
+
+
+SERIAL_ORDER OTG1 USART2 USART1 USART3 UART4 UART5
+
+# UART1 as board 2.1.5 for serial 3 gps
+PB6 USART1_TX USART1
+PB7 USART1_RX USART1
+
+# USART2 serial2 telem2
+PD5 USART2_TX USART2 NODMA
+PD6 USART2_RX USART2
+
+# USART3 serial3 telem1
+PD8 USART3_TX USART3 NODMA
+PD9 USART3_RX USART3
+
+PC10 UART4_TX UART4 NODMA
+PC11 UART4_RX UART4
+
+# SHARE dma with I2C2_TX
+PC12 UART5_TX UART5 NODMA
+PD2  UART5_RX UART5 NODMA
+
+
+#SPI1 for MPU
+PA5 SPI1_SCK SPI1
+PA6 SPI1_MISO SPI1
+PA7 SPI1_MOSI SPI1
+PA4 MPU_CS CS
+
+# spi bus for dataflash AND SD
+PB13 SPI2_SCK SPI2
+PB14 SPI2_MISO SPI2
+PB15 SPI2_MOSI SPI2
+
+
+PB12 FRAM_CS CS SPEED_VERYLOW
+PE15 FLASH_CS CS
+
+SPIDEV mpu6000 SPI1 DEVID1 MPU_CS   MODE3 1*MHZ   8*MHZ
+SPIDEV ramtron SPI2 DEVID2 FRAM_CS  MODE3 8*MHZ   8*MHZ
+SPIDEV sdcard  SPI2 DEVID3 FLASH_CS MODE0 400*KHZ 25*MHZ
+
+# one IMU
+IMU Invensense SPI:mpu6000 ROTATION_NONE
+
+# one baro, check both addresses
+BARO MS56XX I2C:0:0x76
+BARO MS56XX I2C:0:0x77
+
+# enable RAMTROM parameter storage
+define HAL_WITH_RAMTRON 1
+# enable FAT filesystem support
+define HAL_OS_FATFS_IO 1
+
+# this defines the default maximum clock on I2C devices.
+define HAL_I2C_MAX_CLOCK 100000
+I2C_ORDER I2C2 I2C1
+PB8 I2C1_SCL I2C1
+PB9 I2C1_SDA I2C1
+PB10 I2C2_SCL I2C2
+PB11 I2C2_SDA I2C2
+
+# look for I2C compass
+COMPASS HMC5843 I2C:0:0x1E false ROTATION_YAW_270
+define HAL_PROBE_EXTERNAL_I2C_COMPASSES
+
+# PWM out pins
+PA0 TIM2_CH1 TIM2 PWM(1) GPIO(50)
+PA1 TIM2_CH2 TIM2 PWM(2) GPIO(51)
+PA2 TIM2_CH3 TIM2 PWM(3) GPIO(52)
+PA3 TIM2_CH4 TIM2 PWM(4) GPIO(53)
+PE9 TIM1_CH1 TIM1 PWM(5) GPIO(54)
+PE11 TIM1_CH2 TIM1 PWM(6) GPIO(55)
+PE13 TIM1_CH3 TIM1 PWM(7) GPIO(56)
+PE14 TIM1_CH4 TIM1 PWM(8) GPIO(57)
+
+PD13 TIM4_CH2 TIM4 PWM(9) GPIO(58)
+PD12 TIM4_CH1 TIM4 PWM(10) GPIO(59)
+PD15 TIM4_CH4 TIM4 PWM(11) GPIO(60)
+PD14 TIM4_CH3 TIM4 PWM(12) GPIO(61)
+
+# also USART6_RX for serial RC
+PC7 TIM8_CH2 TIM8 RCININT PULLDOWN LOW DMA_CH0
+# PC6 TIM8_CH1 TIM8 RCININT PULLDOWN LOW DMA_CH0
+
+
+# New style Pixracer LED configuration for master repo
+define AP_NOTIFY_GPIO_LED_RGB_ENABLED 1
+
+PE3 LED_RED   OUTPUT GPIO(10)
+PE2 LED_GREEN OUTPUT GPIO(11)
+PE1 LED_BLUE  OUTPUT GPIO(12)
+PE0 LED_YELOW OUTPUT GPIO(13)
+
+define AP_NOTIFY_GPIO_LED_RGB_RED_PIN 10
+define AP_NOTIFY_GPIO_LED_RGB_GREEN_PIN 11
+define AP_NOTIFY_GPIO_LED_RGB_BLUE_PIN 12
+
+
+
+PC0 PRESSURE_SENS ADC1 SCALE(1)
+PC1 RSSI_IN ADC1
+PC2 BATT_CURRENT_SENS ADC1 SCALE(2)
+PC3 BATT_VOLTAGE_SENS ADC1 SCALE(2)
+PC4 VDD_5V_SENS ADC1 SCALE(2)
+PC5 FMU_SERVORAIL_VCC_SENS ADC1 SCALE(2)
+
+
+PE5 TIM9_CH1 TIM9 ALARM
+PC14 EXTERN_GPIO1 OUTPUT GPIO(1)
+PC13 EXTERN_GPIO2 OUTPUT GPIO(2)
+PE4  EXTERN_GPIO3 OUTPUT GPIO(3)
+PE6  EXTERN_GPIO4 OUTPUT GPIO(4)
+PC9  EXTERN_GPIO5 OUTPUT GPIO(5)
+
+#  IRQ for MPU6000
+PB0 EXTI_MPU6000 INPUT PULLUP
+PB1 DRDY_HMC5883 INPUT PULLUP
+
+