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What is required to utilize USART3 on the STMod+ Fan-Out Expansion Board when using the STM32L4P5G-DK Discovery Kit?

Zak
Associate II

I start a new project with the following steps:

  1. I create a new STM32 Project
  2. I select STM32L4P5G-DK from the Board Selector Menu
  3. I initialize the board with it's default configuration

I have successfully configured the I2C4 and USART2 peripherals on the STMod+ Fan-Out Expansion Board, and they are working as expected.

However, I am having difficulty when I attempt to enable USART3 (available on the expansion board) for use with my project. I resolve the conflicts (warnings) and get the "green checkmark" (as I did with the other peripherals), but when I look at the pins on my oscilloscope, there is no activity. What gives?

As far as hardware configuration goes, I'm already using the I2C4 bus on the STMod+ Fan-Out Expansion Board, so I'm assuming the STMod+ (CN1) connector is enabled. Is this a good assumption, or is there a jumper on the board that needs to be configured to "fully activate" the STMod+ connector?

As far as I can see, all signs are go. I need help determining how my firmware or hardware is misconfigured.

Here is the Device Configuration Tool view:

0693W000005Ag24QAC.pngPinout from the User Manual:

0693W000005Ag2EQAS.png

1 ACCEPTED SOLUTION

Accepted Solutions
TDK
Guru

Did you close the necessary solder bridges?

Also seems like you still have SPI1 in use, which will fight for the same pins as USART3, unless you've changed them.

0693W000005Ah12QAC.png

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3 REPLIES 3
TDK
Guru

Did you close the necessary solder bridges?

Also seems like you still have SPI1 in use, which will fight for the same pins as USART3, unless you've changed them.

0693W000005Ah12QAC.png

If you feel a post has answered your question, please click "Accept as Solution".
Zak
Associate II

I was unaware of the solder bridges, so I'm sure that is a problem. Where are they located on the STM32L4P5G-DK? Also, what documentation are you referencing? I would like to learn how I could have found that on my own.

Finally, why doesn't the STMCubeIDE report the pin conflict? Why am I receiving the "green check mark", when there is such an obvious configuration issue?

I'll hunt for the solder bridges, but if you're up for it, I would still appreciate a pointer. In the meanwhile, I've attached my NEW pin configuration, in case you can see any other obvious problems.

0693W000005AhDDQA0.png

> Where are they located on the STM32L4P5G-DK?

The bridge should be labeled on the board. Might take a minute but just looking for it is probably the easiest way. If you get really desperate, you can download the board manufacturing files and Ctrl+F for it.

0693W000005AhGqQAK.png 

> Also, what documentation are you referencing?

The schematic and other stuff are available under documentation on the product page. There is also a user manual, although it didn’t mention the solder bridges at all as far as I could see.

https://www.st.com/en/evaluation-tools/stm32l4p5g-dk.html#documentation

> Finally, why doesn't the STMCubeIDE report the pin conflict?

CubeMX has no idea the pins are tied together (via solder bridges) on the board, so it doesn’t know there’s a problem to report.

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