November 17, 2020

STM32F4xx chips

There are a whole gang of these with different quotas of this and that. They all have an ARM Cortex-M core of some kind. The following is not a comprehensive review, but just an overview of various chips that I have been involved with.


This is what is on my Olimex-P405 board. It seems to be the big boy of the series. There is also a F405OE with only 512M of flash.


This seems to be the same as the F405, but "integrates a crypto/hash processor".


This seems to be identical to the F405. It is available with either 512K or 1M of flash. Always 192K of ram. There is also a 417 that adds the crypto processor.

The only difference I can see is that the F407 adds ethernet.


ST likes to offer these parts in "pairs" presenting the reader with the puzzle of figuring out what is different about a 437. In this case the puzzle still stands unsolved. To my surprise, this seems to be the big brother of the F4 series: It even has an LCD-TFT controller, to offload the processor and provide graphics acceleration. The way to get your hands on one of these is to buy a "discovery board" from Mouser for $30. This gives you a STM32F429ZIT6 part, which does have 2M of flash, along with a 64Mbit SDRAM (8M) a gyroscope and an LCD, which makes it an interesting package. They say it has an onboard ST-Link. The LCD is a 2.4 inch QVGA unit, which is probably 320x200. They boast that it is "Mbed enabled".


This seems to be the "little brother" of the F4 series. You get 256K or 512K of flash and "up to" 128K of ram. The Cortex M4 core runs at 100 Mhz. You do get FPU and DSP.


This seems to be an even "littler brother", giving you 256K flash and 64K of ram. The CPU runs at 84 Mhz. You do get the M4 core with FPU and DSP.

Black Pills

Some Black Pills from China are just Blue Pills with an STM32F103 and a black PCB. The true "black pill" boards from China give you either an F401CCU6 or an F411CEU6. These are very likely not genuine ST parts, but Chinese clones, but who knows.

My black pills just arrived and they are indeed marked STM32F411CEU6.


Note that the letter is now "H" in lieu of "F" (I have also seen "L"). The H743 is a big brother to the H750 in the same family.

Note that there are both F7 and H7 parts. The F7 parts typically run at 216 Mhz, while the H7 run at 480 Mhz. It uses a 40nm process rather than a 90nm process.

The H743 runs at 480 Mhz, has I and D cache, has an M7 core with MPU, FPU, and DSP. These come with 1M of ram and either 1M or 2M of flash. The chip includes ethernet, but not all boards provide a connector.

A very affordable and nice option is a Nucleo-H743ZI2 from Mouser for $27

This has an integrated ST-Link and ethernet and are part of a family of "Nucleo-144" boards. The chip is an STM32H743ZIT6U. The "I" in the part number indicates it has 2M of flash. A "G" would indicate 1M of flash.

What first got me started on all of this was discovering some inexpensive boards on AliExpress. They want $24 including shipping and their board does not include ethernet, making the board from Mouser a much better choice.

Feedback? Questions? Drop me a line!

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