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JZipf.1
Associate II
November 19, 2020
Question

Can someone help me check if my schematic works? If you have any suggestions of corrections please tell me I need all the help I can get

  • November 19, 2020
  • 3 replies
  • 2262 views

Im really brand new here and I wanted to ask some of you guys to help me. Im using the STM32F722RET6 MCU and this probably ***** but Please feel free to critique as mush as you want and make as many suggestions possible. The following pdf is my schematic and I'm just trying to learn and set up the correct connections.

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3 replies

TDK
November 19, 2020

All VDD/VSS pins need to be connected to power and ground. There should also be a 0.1uF bypass cap near each pair of these pins.

A bulk capacitor on VDD should be present somewhere near the chip. Usually 2.2uF or 4.7uF will be fine.

nRST should have a 0.1uF capacitor to ground to avoid spikes due to noise/crosstalk.

The load capacitors on X1 should be in the 10pF range. Very likely 0.1uF won't work here.

Read this:

https://www.st.com/resource/en/application_note/dm00164549-getting-started-with-stm32f7-series-mcu-hardware-development-stmicroelectronics.pdf

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JZipf.1
JZipf.1Author
Associate II
November 19, 2020

Thanks for the advice and tips

TDK
November 19, 2020

I edited it to clarify all VDD/VDDA pins need to be connected to 3.3V (or whatever), and all VSS/VSSA need to be connected to ground.

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gregstm
Senior II
November 19, 2020

I don't like the Boot0 set up. When Boot0 is pulled High there is unlimited current through the Led. You are relying on the reliability of a switch to keep Boot0 pulled low - and and I have found over the years that mechanical things always cause problems. I would prefer you permanently connect Boot0 to Ground via a 10K resistor, and pull it high when needed (using the switch - and the 10K could also act as the current limiter for the Led). Boot0 is an input, and not connected to the outside world, so I think having a 1K resistor is redundant.

gregstm
Senior II
November 19, 2020

... second thoughts, if you need the Led, use a separate current limiting resistor for it. The Led's voltage drop will interfere with the High level voltage obtained on the Boot0 pin.

JZipf.1
JZipf.1Author
Associate II
November 19, 2020

thanks man this helped me a lot

Piranha
Principal III
November 20, 2020

For MCU the VCAP1 pin also need 4,7 uF ceramic capacitor to the ground. For this one the 1206 package is recommended. AN4661 contains all of that information:

In the STM32F7x2Rx devices, only the VCAP1 pin is available and must be connected to 4.7 µF low ESR between 0.1 Ω and 0.2 Ω ceramic capacitor.

D1 pin 5 must be connected to USB1 VCC and a 100 nF as per datasheet.