How may external signals am I able to read with a STM32F469I-DISCO using ADC?

[Danodino]

Hello!
I'm starting a project where I need to read several external analog signals simultaneously. The reference manual of the STM32F469I-DISCO states that its ADC has up to 16 channels to measure analog signals. However, upon reviewing the schematic of the board, I realized that there aren't enough physical connectors for the ADC channels (or at least that's what I found—I'm still a beginner). Is there any way to solve this problem, such as using an external module or board?

I appreciate your responses and assistance very much.

[STTwo-32]

Hello @Danodino and welcome to the ST Community 😊.

the STM32F469I-DISCO is based on the STM32F469NIH6 MCU wish (according to the DS11189) give you the opportunity to use 24 ADC channel on the same time:

If you are looking for more ADC channels, you can even look for another MCU that support more channels (ST-MCU-FINDER-PC may help you). Or you can use an external ADC to SPI converter that add some ADC channels throw SPI interface.

Best Regards.

STTwo-32

[Andrew Neil]

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@Danodino wrote:

The reference manual of the STM32F469I-DISCO states that its ADC has up to 16 channels to measure analog signals.

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You mean the User Manual, UM1932?

https://www.st.com/resource/en/user_manual/um1932-discovery-kit-with-stm32f469ni-mcu-stmicroelectronics.pdf

I don't see "16 channels" mentioned in there?

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@Danodino wrote:

However, upon reviewing the schematic of the board, I realized that there aren't enough physical connectors for the ADC channels

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That's the trouble with a development board like that - which has a loads of accessories bolted on:

All of those things use up processor pins - meaning they're not free for you to use for other things.

If you want maximum unobstructed access to as many of the chip's pins as possible, you want a dev board with as few "extras" as possible.

So you'd be better looking at a Nucleo board - they are pretty minimalistic in terms of the "extras":

https://www.st.com/en/evaluation-tools/stm32-nucleo-boards.html

[AScha.3]

Hi,

STM32F469I-DISCO has some ADC inputs on connectors, you can use:

So you have : 6 x adc in on CN8 , some (4x) on CN5+7 :  PA1/2/6/7 , (2x) on CN12 : PA5 , PC1 ; 12x i found.

maybe more, just look in ds pinouts for all pins on the headers.

How many you need ? + you have all the opamps+circuit to bring clean 0...3v3 signals to the inputs ?

[Danodino]

Hello again,

Thank you very much for replying, @AScha.3. 🙂

Being optimistic, I need to read 12 signals (I'm developing a system for electrocardiography recording), but I can reduce it to only 6 signals if necessary.

I found the ones you mentioned on CN8 and CN12, but I don't know how you identified the 4x from CN5 and CN7; there is no label related to ADC channels (it would be awesome if there are actually 12 available channels). Could you explain how you figured them out?

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@AScha.3 wrote:
How many you need ? + you have all the opamps+circuit to bring clean 0...3v3 signals to the inputs ?

My analog circuit is supplied with a symmetric source of ±12V. My outputs are supposed to be in the -1.5V to 1.5V range, but there isn't any extra circuit that ensures my output won't be greater than 3.3V and less than 0V. Now, I realize that I have to add that to my PCB and make the pertinent modifications (thank you for that).

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[AScha.3]

Hi,

Let your book of wisdom be the manual .

Here it is the ds and the rm , about 1800 pages, and the board circuit diagram .

In circuit diagram you see, what pins you could use to connect , 

and in ds look in pin definitions, whats on these pins: looking for ADC inputs you see, they are on some group of pins:

So  PA1/2/6/7 can be switched to adc inputs ...

Now : what you should do , to go on ->

Use the comfort, the stm32CubeIDE or CubeMX offers you:

Start new stm32-project, select your 469-disco board and give a name and let it work some minutes...

then have a pinout picture, where you can see whats connected and change/set the analog inputs you want to the ADCs . Then generate code and you can start programming .

And if you have a problem...someone (me?) will show you how to do.

[Andrew Neil]

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@Danodino wrote:

I'm developing a system for electrocardiography recording

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I'd be doubtful that this Disco board is optimised for low-noise on its analogue inputs ...