How can i link 2 wifi+mcu boards with one as the access point?

[JTech]

Hi community!

I am working on a hobby project (custom pcb) where i need my stm32 mcu to communicate with a wifi chip, which will send data to a second pcb which is a usb dongle with a similar mcu+wifi setup, only that wifi chip acts as an access point only the first mentioned wifi chip can access and send/receive data from.

How would i go about this and what wifi chip is recommended for it?

I am planning to use the STM32H745IIT6. (maybe a bit overkill, but i need it to process a lot of stuff).

Another thing is that i want to connect 16 small boards, (which contain a BMM350 and a BMI323) to the MCU via I2C, because the STM32H745IIT6 has 4 I2C Interfaces. Is this feasable to do?

I appreciate the assistance.

Thanks,

[Pavel A.]

There are wi-fi modules that support both AP and station modes, for example this one is used in some ST eval. boards: MXCHIP EMW3080B. And there are ESP8266 and other ESP chips. 

[JTech]

Thanks!

I will probably use the ESP8266EX.

Any tips on the second part of the question?

For some more clarification, the STM32H745IIT6 has 4 I2C interfaces i'm using, and it also has 4 SPI interfaces i could use. Would i be better of using The I2C interfaces, the SPI interfaces, or a combination of both?

[AScha.3]

Hi,

1 - ESP8266  is ok (but ESP32-S2-mini  : i would think about using it and no H7 , cpu here 32bit/240MHz (almost same power as an H7 ), and 2MB RAM , 4MB flash + SPI, I2C etc... at 2,50 !

https://de.aliexpress.com/item/1005005977413920.html

2 - How long will be connection line to this gyro/magnetic sensors ? screened ?

[JTech]

Hi,

1) Thanks for the suggestion! Will definately look into that.

2) Quite long since the 16 sensor packages are individual motion trackers that are relatively far appart

[AScha.3]

I just asked, because in my experience I2C with more than 100mm wire making problems.

Especially with STM CPUs I had no reliable communication.

Much better with SPI here, even at high speed, 16 or 48 Mbit!

Example: I use SPI at 16Mhz to transfer audio data streams from ESP 8266 to H743 CPU over 40cm distance, using a Cat6 network cable.

[JTech]

Ah i understand now, thanks for the clarification.

So SPI would be able to handle up to 16 devices (split across 4 SPI interfaces) right?

[David Littell]

I think we need a much more complete description of your application in order to suggest anything cogent.