STM32F4 Discovery ADC

[tiche79]

Posted on February 07, 2014 at 10:46The original post was too long to process during our migration. Please click on the attachment to read the original post.

[chen]

Posted on February 07, 2014 at 11:29

Hi

''

It's the first time that I use the STM32F4 Discovery Board and I have a problem with the ADC.

'' Welcome. Please specify which F4 Discovery board, I think there are 2 different models? ''

I wired on a breadboard with 4 potentiometers (10k) for each channel.

'' ''

But with the two others channels when I vary the potentiometer for the channel 10 (PC0) their values change but also that of channel 4 (PA4).

'' Please check the circuit diagram/schematic of the Discovery board you have. I remember other posts/threads mentioning that some port bits are actually used for things on the demo board and therefore cannot be used for your purposes.

[tiche79]

Posted on February 07, 2014 at 12:01

Thanks for your response

I use the STM32F4 Discovery kit for STM32F407.There is effectively something else plugged on the pin that I use for the ADC.I use this kit to try the different functions that I created because after I'm going to use the STM32F407 for a personal project.Do you think I will have the same problem ?   Thanks

[chen]

Posted on February 07, 2014 at 13:00

Hi

''There is effectively something else plugged on the pin that I use for the ADC.'' ''Do you think I will have the same problem ? '' Yes. If the pin is in use on the Discovery board, it is in use. Even on the break out header. (IF you want to - you can cut the tracks on the Discovery board. Consult the schematic and the gerber file. Just make sure that the pin is still wired to the break out header)

[raptorhal2]

Posted on February 07, 2014 at 16:34

This is what I call my deja vu all over again question.

There is a table in the F4 Discovery User Manual that defines which pin are connected to board functions and which are free for other uses such as yours. ADC123 channels 1,2,3,8,9,11,12,14 & 15 are free. Cheers, Hal

[tiche79]

Posted on February 07, 2014 at 18:48

OK thanks

So if I have well understood, if I use the STM32F407 in a personal project without the discovery kit, I can use all ADC and all channels ?

[chen]

Posted on February 07, 2014 at 19:01

Hi

''So if I have well understood, if I use the STM32F407 in a personal project without the discovery kit, I can use all ADC and all channels ?'' Yes. Bear in mind that the correct circuitry must surround the STM32F407 or it will not work. Search the STM32 forum, there have been a few people who have built their own boards. There was 1 post in which clive1 answered where he posted the bear minimum circuit needed.

[raptorhal2]

Posted on February 07, 2014 at 20:20

''So if I have well understood, if I use the STM32F407 in a personal project without the discovery kit, I can use all ADC and all channels ?''

Yes. Sung is correct, but you need to consider the pin count limitations. Look over the pin definitions table in the F407 data sheet. 24 external channels are available, but only in higher pin count packages. And any one ADC is limited to 16 external channels. And ADC pins share functions with other peripherals, which may or not be reassignable to other pins. Cheers, Hal

[Tesla DeLorean]

Posted on February 07, 2014 at 20:25

In a design of your own you can use pins for whatever combination of features you want.

It is pretty much impossible to use ALL of the peripherals ALL at once, you are limited by what features you want, and what you can escape the packaging/pins of the device.Review the 

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/DM00037051.pdf

 for the part.Utilize the Micro Xplorer application, which is a pin assignment ''fitter'' type application designed by ST

[tiche79]

Posted on February 10, 2014 at 15:26

It works 😉 

Thanks