Hi everyone.

A quick question about the ST32F4 and its pinout/bare minimum set up..

Supposing I wished to mount this MCU on to a PCB with nothing more than the minimum, being able to flash, power and stream data via USB, how many pins could I run as straight digital I/O?

Also, can I program the MCU with a USB to Tx/Rx?
(eg. 16U2/32U4)

I'm finding the datasheets a little hard to follow..

 

Hi everyone.

A quick question about the ST32F4 and its pinout/bare minimum set up..

Supposing I wished to mount this MCU on to a PCB with nothing more than the minimum, being able to flash, power and stream data via USB, how many pins could I run as straight digital I/O?

You need to state which STM32F4.

Also, can I program the MCU with a USB to Tx/Rx?
(eg. 16U2/32U4)

No. The simplest thing to do is get a STM32F4DISCOVERY board.

 

Thanks for replying.

I currently have a Discovery with the VGT6Z version..

I was intending to get this MCU as is on a standalone PCB.

How would I go about flashing/interacting with USB etc?
Could I use the Discovery to program from (using the onboard ST-Link/V2)?

 

Yes, you can use the ST-LINK on the STM32F4DISCOVERY to program a target mcu.

You only need three connections from SWD CN2 to the target mcu:

pin 2 - JTCK to mcu pin 76
pin 3 - GND
pin 4 - JTMS to mcu pin 72

Remove two jumpers at CN3 to disconnect the DISCOVERY mcu.

On your target 100-pin STM32F407VGT6
make sure all the VDD, VDDA pins are connected to your 3.3V source
and VSS, VSSA pins are connected to GND.

Install 2.2μF capacitor from VCAP_1 (pin 49) to GND.
Install 2.2μF capacitor from VCAP_2 (pin 73) to GND.

 

As a standalone would this work?

Taken from MicroXplorer. (STM32F407V(E-G)Tx 100pin:

Pin/connection:

10/VSS_PWR
11/VDD_PWR
14/NRST
19/VDD_PWR
20/VSSA_PWR
22/VDDA_PWR
27/VSS_PWR
28/VDD_PWR
49/VCAP1_PWR
50/VDD_PWR
73/VCAP2_PWR
74/VSS_PWR
75/VDD_PWR
94/BOOT_RST
99/PDR_on(RST-State)
100/VDD

I am a little confused by the multiple pinout for various power?
Do all of these need to be connected for the standalone?

Is this all 3.3v, or are there certain pins that are 5v/3.3v?

 

All VDD and VDDA pins are 3.3V.

Yes, all VDD and VSS pins need to be connected,

Multiple VDD and VSS (GND) pins are very common for a larger mcu such as the STM32F.
This spreads the power load and reduces overall pin inductance.