STM32 Nucleo and DFU USB Bootloading

Over the last few months I have been playing with the Nucleo development boards from STMicroelectronics. If you're unfamiliar with them, they are fast, mbed and Arduino (headers) compatible. This makes it easy like an Arduino to program and use. What sets them apart is that they are 32bit and have, depending on the model, tons of memory and flash. The Nucleo boards maintain the Arduino footprint but also have headers for the extra pins which gives this board plenty of GPIO for your projects.  In turn, you end up with multiple buses such as SPI, I2C, and UARTs for your consumption. They are priced very well and come in different flavors based on your needs. Each flavor is based on different ARM Cortex architectures such as M0, M3, and M4. One of the best features is real debugging via ST-Link/V2-1. The unfortunate thing due to the nature of mbed, you can only use the debugging features using a full desktop IDE such as Keil or some of the other free alternatives. But mbed allows you to export your code from the online IDE to the project format for those IDE's. So there's that.

Most of my projects spend very little time on the development board. Once they are working, I usually want to design a PCB for it. Therefore I prefer to use microcontrollers that support native USB programming, such as the popular ATMega32U4. With some AVR chips you can use the Arduino bootloader but most chips come with a DFU bootloader that can support flashing over serial and USB. In the case of STM32, it additionally supports CAN, I2C, and SPI bootloading. For some reason the Nucleo boards don't have the native USB connector onboard, but the needed pins are available for easy access. (The discovery boards do.)

Connecting USB Pins

To access these pins you can use a USB breakout or a USB Tester. Of course you could always cut open a USB cable, but seriously, why create a mess? If you have one of my USB, Testers it makes it much easier, plus all of the other features it provides. BUY ONE NOW!! Just kidding! The pins for D+ and D- are not labeled on the pin out of the Nucleo board out but if you look up the datasheet you can find them and match the pin names with the Nucleo pin out as shown below.

So far I have tested the L152 and F411 and both have been PA12, PA11 (D+, D-). Which is pin 6,7 from the top on the right most column of male headers.

STM32 Nucleo USB DFU Connections