STM32F4 Discovery

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This page is for the STM32F4 Discovery board with STM32F407VGT6, STM32F4 Disco is a familiar board with STM32F401VCT6, do not use this Files for the Disco board !

STM32F4Discovery front.jpg STM32F4Discovery back.jpg


  • STMicroelectronics STM32F4VGT6 Cortex M4 MCU, up to 168Mhz with floating point unit (FPU), 192 KB RAM, 1024 KB Flash
  • on-board STLinkv2 with SWD header (capable of programming onboard or external MCU)
  • on-board power regulator for the MCU (3V or 5V Input)
  • 1 x user push button
  • 4(5) x LED (orange, green, red, blue, green)
  • 4(6) x UART (UART1, UART2, UART3, (UART4, UART5), UART6)
  • 1(3) x SPI (SPI1, (SPI2, SPI3))
  • 2(3) x I2C (I2C1, I2C2, (I2C3))
  • 6 x ADC inputs (one is used for BAT voltage)
  • 1 x PPM input
  • 1 x Spektrum input (with bind pin)
  • 97 x 66 mm PCB
  • 4 x status LED (USB red, USB green, power, USB OTG green, USB OTG red)
  • LIS302DL MEMS 3 axis accelerometer on SPI1


The Discovery has a male 100 pin (2x25pin on both sides, also accessible on both sides of the pcb) pinout.

Pin # Name Type Description Color
PD13 LED_3 Out above LIS302DL Orange
PD12 LED_4 Out left of LIS302DL Green
PD14 LED_5 Out right of LIS302DL Red
PD15 LED_6 Out below LIS302DL Blue
PA9 LED_9 Out same as USB power (VBUS, needs to be enabled in header file) Green

Pin # Name Type Description
PB6 UART1 TX Out UART1 Serial Output, 4k7 pullup for I2C
PB7 UART1 RX In UART1 Serial Input

Pin # Name Type Description
PD5 UART2 TX Out UART2 Serial Output (usb otg power management fault output open drain)
PD6 UART2 RX In UART2 Serial Input, also used for Spektrum input

Pin # Name Type Description
PD8 UART3 TX Out UART3 Serial Output
PD9 UART3 RX In UART3 Serial Input

UART4 (Can NOT be used if SPI_3 is active!)
Pin # Name Type Description
PC10 UART4 TX Out UART4 Serial Output
PC11 UART4 RX In UART4 Serial Input

UART5 (Can NOT be used if SPI_3 is active!)
Pin # Name Type Description
PC12 UART5 TX Out UART5 Serial Output
PD2 UART5 RX In UART5 Serial Input

Pin # Name Type Description
PC6 UART6 TX Out UART6 Serial Output
PC7 UART6 RX In UART6 Serial Input

SPI1 (for onboard LIS302DL)
Pin # Name Type Description
PA5 SPI1 SCK I/O SPI1 Serial clock
PA6 SPI1 MISO I/O SPI1 Master In Slave Out
PA7 SPI1 MOSI I/O SPI1 Master Out Slave In
PE3 SPI SS2 I/O SPI1 Select Slave2

Pin # Name Type Description
PB3 SPI1 SCK I/O SPI1 Serial clock
PB4 SPI1 MISO I/O SPI1 Master In Slave Out
PB5 SPI1 MOSI I/O SPI1 Master Out Slave In
PE2 SPI SS0 I/O SPI1 Select Slave0

SPI2 (Can NOT be used if PWM10 & PWM11 is active!)
Pin # Name Type Description
PB13 SPI2 SCK I/O SPI2 Serial clock
PB14 SPI2 MISO I/O SPI2 Master In Slave Out
PB15 SPI2 MOSI I/O SPI2 Master Out Slave In
PE7 SPI SS1 I/O SPI2 Select Slave1

SPI3 (Can NOT be used if UART4 & UART5 is active!)
Pin # Name Type Description
PC10 SPI3 SCK I/O SPI3 Serial clock
PC11 SPI3 MISO I/O SPI3 Master In Slave Out
PC12 SPI3 MOSI I/O SPI3 Master Out Slave In
PE3 SPI SS2 I/O SPI3 Select Slave2 (also used for LIS302DL (SPI1) Slave Select)

Pin # Name Type Description
PB8 I2C1 SCL I/O I2C1 Serial Clock
PB9 I2C1 SDA I/O I2C1 Serial Data

Pin # Name Type Description
PB10 I2C2 SCL I/O I2C2 Serial Clock (also used for MP45DT02 MEMS MIC clock in)
PB11 I2C2 SDA I/O I2C2 Serial Data

I2C3 (Can NOT be used if Spektrum bind / PPM input is active!)
Pin # Name Type Description
PA8 I2C3 SCL I/O I2C3 Serial Clock
PC9 I2C3 SDA I/O I2C3 Serial Data

Note: is disabled in header file, PA8 is used as Spektrum bind pin, PC9 is used as PPM (not Spektrum) input

Pin # Name Type Description
PA4 AUX4/BAT I/O ADC_4, is used for BAT voltage

Pin # Name Type Description
PE9 PWM0 Out Servo 1
PE11 PWM1 Out Servo 2
PE13 PWM2 Out Servo 3
PE14 PWM3 Out Servo 4
PE5 PWM4 Out Servo 5
PE6 PWM5 Out Servo 6
PA3 PWM6 Out Servo 7
PA2 PWM7 Out Servo 8
PA1 PWM8 Out Servo 9
PA0 PWM9 Out Servo 10
PB14 PWM10 Out Servo 11, Can not be used if SPI2 is active
PB15 PWM11 Out Servo 12, Can not be used if SPI2 is active

Pin # Name Type Description
PC9 PPM In PPM input (remember, you need 100 Ohm serial termination in order to use this)

Pin # Name Type Description
PA8 Bind Out Spektrum bind pin
PA10 PPM IN Spektrum PPM in


Pin # Name Type Description
JP1 JP1 Switch MCU Current can be measured here
CN3 CN3 Switch closed: STLinkV2 is connected to onboard MCU, open: is not connectec to onboard, only external header

Soolder Jumper
Pin # Name Type Description
SB17 SB17 Switch Bypass for JP1, close this for security ! (if JP1 gets loose there is no power supply for the mcu)


Currently we have two different breakout/baughter boards.

SMD & Molex

Another option with Molex connectors, levelshifters for I2C and SPI, as well as connectors for Spektrum satellites and a can phy would be:

DiscoveryBreakout1 small.jpg DiscoveryBreakout2 small.jpg

Currently under testing, eagle files are coming, when its completely finished and airworthy :-)


Target for this board is to be a ultra low cost THT daughterboard which should provide as many functions as possible. Also it should be as simple as possible (hence no SMD Components were used).


  • Tall screw terminals can touch the THT solder joints from the discovery board. No electrical but a mechanical contact can appear. Don't force both pcb's all the way together (leave a small gap).
  • Only mount the components needed.
  • If IR_Sensors are used used, maybe the diodes shouldn't be mounted and the voltage divider should be changed.
  • If you use the 22k/2.2k voltage divider for the BAT input, you need to change the VoltageOfAdc see Airframe_Configuration#Battery.

Servo Power options

  • External power source (to power servos with a higher voltage or an other voltage regulator, only GND stays connected).
  • Power servos from the 5V rail, solder the two solder bridges benesth the three row header.

The servo rail also powers the RC receiver directly (PPM and Spektrum), take care of that if this rail runs on a higher voltage than 5V!
Servo and 5V net share the same GND!

IMU mounting options

  • Drotek 10 DOF can be soldered on the appropriate footprint. (If mounted with the analog header facing front and pcb level with the wing, phi, theta and psi need to be 180 degree offset)
  • Other 6/9/10DOM IMU, can be soldered on the prototyling area. Use wires to make connections between the e.g. the Drotek footprint and the IMU (if the other IMU one has a different pinout)
  • Mount IMU elsewhere and connect it with cables.

BAT voltage
If you use the 22k/2.2k Resistor divider, you will need to redefine the values for the ADC conversation.

File: conf/airframes/myplane.xml
  <section name="BAT">
    <define name="VOLTAGE_ADC_SCALE" value="0.008864469"/> <!-- R1 (Bat - ADC input) = 22k, R2 (ADC input - GND) = 2.2K--->
    <define name="VOLTAGE_OFFSET" value="0" unit="V"/>
    <define name="VoltageOfAdc(adc)" value="(VOLTAGE_ADC_SCALE * adc + VOLTAGE_OFFSET)"/>

Also see Airframe_Configuration#Battery.

Stm32f4discovery daughterboard.jpg Stm32f4discovery with daughterboard.jpg

Firmware Flashing

FLASH_MODE=STLINK is set as default

STM32F4 Discovery can mainly be programmed in two different ways:


  • with onboard STLinkV2 over SWD
  • required hardware: usb to mini USB cable
  • required software: st_flash and st_util from Texane
  • more information: STLink page


  • with the MCU native (embedded in rom) DFU USB bootloader over the micro USB AB connector
  • required hardware: USB to micro and USB to mini usb cable
  • required external software: dfu-util
  • push MCU in DFU mode: connect mini(for power) and micro USB to PC, connect pin BOOT0 with 3V, press reset button(LED LD7 should light up now), disconnect BOOT0
  • more information: DFU page