Pin termination normally & after power up STM32

[vindhyachal]

Posted on August 14, 2015 at 12:22

I am using STM32F205 LQFP64 & want to know if below configuration of pin are ok. I use SWD method.I have grouped pins as:

1. vbat:  If not used, connect it to Vdd & decouple by 0.1uf cap.

2. PA0-PA15: If any of pin is not used, make it internal pull up or output low after power up 

Except PA13(SWDAT) & PA14(SWCLK).Leave these pins float as they have internal pull-up/down according to datasheet.

3. PB0-PB15: If any of pin is not used, make it internal pull up or output low after power up

4. PC0-PC15: If any of pin is not used, make it internal pull up or output low after power up. 

Except PC13, PC14, PC15 as these have alternate function with RTC oscillator & alarm. Should I also make them internal pull up or output low after power up in case not used?

5. PD2: if not used, make it internal pull up or output low after power up

6. PH0-PH1: Alternate function with main oscillator. Should I also make them internal pull up or output low after power up in case I am using internal oscillator?

7. NRST: decouple with 0.1uf cap, it has internal pull-up according to datasheet.

8. Vcap1-vcap2: Decouple with 2.2uF cap each.

9. VDD1-VDD4, VSS3-VSS4: Decouple each vdd with 0.1uF cap, with additional 4.7uF decouple cap on one vdd.

10. VDDA, VSSA: decouple with 0.1uf & 1uf cap.

11. Boot: pull down with 10K because code is exceuted form flash.

[Nesrine M_O]

Posted on August 14, 2015 at 15:02

Hi takniki.vindhyachal,

Have a look to the  

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/application_note/CD00292095.pdf?s_searchtype=keyword

 , you find all information about hardware implementation of the development board features.

Some good practice to minimize current consumption is putting all non-used pins as analog. 

-Syrine-

[vindhyachal]

Posted on August 15, 2015 at 21:07

I had got these points from one of these files.

I had asked these to confirm, since i am getting very strange problem in my test boards:

as here:

https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Flat.aspx?RootFolder=%2fpublic%2fSTe2ecommunities%2fmcu%2fLists%2fcortex_mx_stm32%2fSWD%20floats%2c%20STM32F2%2c%20code%20don%27t%20run&FolderCTID=0x01200200770978C69A1141439FE559EB459D7580009C4E14902C3CDE46A77F0FFD06506F5B&TopicsView=https%3A%2F%2Fmy%2Est%2Ecom%2Fpublic%2FSTe2ecommunities%2Fmcu%2FLists%2Fcortex_mx_stm32%2FAllItems%2Easpx&currentviews=53