In BOOT mode stand GPIO pins

[wwwharry]

Posted on July 02, 2013 at 18:01

Dear Developers,

I wrote a program which is set to a low level of PE3 Pin. BOOT mode is switched to the next step when the PE3 Pin measured high levels.

This can cause serious problems in future developments. Therefore, I ask, why is this happening? Where to look, how to BOOT mode voltage levels in the Pins?

Thanks for the answers.

I'm sorry for my bad english.

#boot

[Tesla DeLorean]

Posted on July 02, 2013 at 18:39

I wrote a program which is set to a low level of PE3 Pin.

PE6 on what chip/board? How are you driving/setting it low? What does the code look like?

BOOT mode is switched to the next step when the PE3 Pin measured high levels.

How does it get high? Is this your BOOT mode, of the System Loader via BOOT0/BOOT1 pins?

This can cause serious problems in future developments.

Can what cause problems?

So, if I understand, you set the pin LOW in software, and then externally you drive it HIGH? That would be a problem as you have TWO OUTPUT fighting. Why are you doing this?

Wouldn't the more reasonable solution be to use the pin as an INPUT? With a PULL DOWN resistor (Internal/External), and then switch that HIGH later.

Therefore, I ask, why is this happening?

Why is what happening?

Where to look, how to BOOT mode voltage levels in the Pins?

 

I'm not sure I understand. Please describe the problem more clearly, use a schematic or diagram if that is helpful. You can attach PNG/JPEG using the ''Mountain/Sun'' icon. You can paste in code using the ''Paint Brush [<>]'' icon.

[wwwharry]

Posted on July 03, 2013 at 11:58

Dear Clive1,

I will try to describe my problem.

We want to create a control with Cortex MCU. We do not know this controller, so we  purchased a developer board 

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00039084.pdf

. We will want in future own board planning, so we test this developer board.

A friend of mine has developed a STM32F1XX-type microcontroller. Made the HW, integrated environment, it worked normally. However, because development was literally in the meantime wanted to change the code so that crossed boot mode to re-program the MCU.

Then I set her in normal mode after reset the microcontroller low levels, refused to follow this boot mode, and turn an actuator on the controller.

Before we purchased from a developer development board 

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00039084.pdf

. I tested this problem.

I wrote a program that sets up the PE3 pin low (after reset is I/O pins). I measured by the multimeter to 0 volts  (I do not change to HW). Then turned it boot mode (BOOT0->VDD), and the PE3 pin looking with multimeter's. There was 2.94V.

Looking at the data sheet 

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00039084.pdf

, and found that the PE3 pins as free I/O. I would have expected that floating state will be the IC pins. If you do not know which foot is changed when the boot mode step can lead to problems.

The hadver is default, the software worked (I have tested other pins and it worked well.).

How do I know that a foot default boot mode input or output, and high or low signal levels involved in?

Thank you very much for your help.

[Tesla DeLorean]

Posted on July 03, 2013 at 16:48

I'm not sure of any reference to PE3 being used by the System Loader.

PE3 is connected to the CS_I2C/SPI pin of U5 (LIS302DL) on the STM32F4-Discovery board. The table suggests this is PE2, the schematic says otherwise, as does the demo software. ST might want to fix that.

 ''When no communication is on-going, data on CS, SPC, SDI and SDO are driven by internal pull-up resistors''

http://www.st.com/web/en/resource/technical/document/application_note/CD00167594.pdf

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00135460.pdf

Table 5, Page 28 is WRONG wrt PE2 and PE3

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00039084.pdf

[Tesla DeLorean]

Posted on July 03, 2013 at 16:54

[wwwharry]

Posted on July 09, 2013 at 15:53

I have never thought that the document can be bad. Thus, it is clear to all.

Thank you very much for your help.

[Amel NASRI]

Posted on July 16, 2013 at 12:52

ST might want to fix that.

Already aware of this issue reported in this [DEAD LINK /public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Flat.aspx?RootFolder=/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/STM32F4%20SPI%2c%20Weird%20signals%20on%20the%20MOSIMISO%20lines&FolderCTID=0x01200200770978C69A1141439FE559EB459D7580009C4E14902C3CDE46A77F0FFD06506F5B&currentviews=245]thread, it will be fixed in coming user manual revision.

-Mayla-