Solution for sending 3-axial accelerometer analog data wirelessly.

[JKhai.1]

Hello, I haven't any experience with STM programming.

So do you advise me to buy the STM WL series for sending my data? And do I need 2 MCU to transmit/receive the data? Or just an MCU with a receiver ( please note that my data needs to be taken as input to my labVIEW code )

Thank you for your replies as they mean a lot for my project

[Eleon BORLINI]

Hi @JKhai.1​ ,

there could be some design kit that you might consult for implementing your application.

First, what do you mean precisely with "wireless" communication? BLE, WiFi, or something else?

A kit that implements some of these protocols is the B-L4S5I-IOT01A: in this case, you acquire the sensor data on the board (the edge) and you send them to the Cloud; the kit is equipped with various software examples to connect to cloud servers, from where you can download data. The accelerometer used in this case is the LSM6DSL.

If you otherwise want to implement a complete RX-TX setup "on the edge", you could exploit the more recent STM32WB5MM-DK module: I'm not an expert of this tool, but it embeds an STM32WB5MMG (1-Mbyte Flash memory, 256-Kbyte SRAM, in Module RF package MCU) and an accelerometer/gyroscope sensor. There are some examples, if you surf that product's st.com page, and there are also free software libraries and examples available with the STM32CubeWB MCU Package.

Let me know if these hints can help you.

-Eleon

[JKhai.1]

Hello,

First, to be more precise on my project, I will give a little description:

I have a wired analog 3-axial accelerometer (KS943B100) - Datasheet attached. It has an IEPE output. I want to migrate my system to a wireless one (without using the cloud, because my system is outdoors and not stationary) . So the  B-L4S5I-IOT01A is not convenient in my application

So I want to process its signal and send it to my PC directly, then utilize the data with LabVIEW. There are some standards that I have to follow. ADC: 12bit, 20ksps sampling (I might need an anti-alias filter).

In conclusion, I have my analog sensor, and I will need to procure either 2 MCUs with a wireless module or 2 MCUs with embedded wireless module to send my data, right?

My main concern is how to connect my sensor to the MCU in order to read its data without noise problems. What about impedance matching

Not being this experienced in ST products and programming, do you advise me to buy external ADCs, an ST wireless module compatible with arduino with the MCU?

Or do I procure 2 ST embedded wireless MCUs?

Thanks for your help.

[Eleon BORLINI]

Hi @JKhai.1​ ,

sorry for the delay in my answer. Your application is clearer now.

If you don't already have a receiver (so that you are constrained in a certain wireless protocol and a certain technology), you are only bonded to the ADC for the device acquisition. Please note that the IEPE interface is not a standard one, you probably need an additional interface between the MCU and your sensor (I see this one from TI, but although I'm not an expert I don't believe ST has one...)

If you are not familiar with STM32, it's always the right time to start with :D but ok, the solution you are suggesting:

>> do you advise me to buy external ADCs, an ST wireless module compatible with arduino with the MCU?

is probably the most suitable one, if the ADC embedded in the Arduino MCU is not powerful enough for your requirements (12bit, 20ksps, with an anti-alias filter that is always a good practice in an analog acquisition).

-Eleon

[Tesla DeLorean]

>>ADC: 12bit, 20ksps

That alone is 240kbps

Over what kind of distance?

Would WiFi be a better choice?

[JKhai.1]

@Eleon BORLINI​ 

Hello again,

Thanks for the reply.

Yes, it is noted, I would require a constant current source for the IEPE sensor.

In fact, I like STM32 because its ADCs are convenient in my application for example the STM32WB50CG has 12 bit ADC reaching 2.13MSPS.

If I would like to choose STM32 wireless MCUs, is there a receiver to my laptop to directly retrieve the data? Or the best way to receive data is to have an other MCU acting as a receiver (Please note that I need to use the data in my LabVIEW application)

@Community member​ 

Only over 1-2m (maximum)

I think it will be a good choice if LabVIEW can directly receive data from the MCU's IP address with Wifi protocol. So which MCU/Wifi Module do you think will work fine?

(I will attach a video of a measurement of shock for you to have a clear idea of my application: The wired accelerometer is inside the ball that is simulating the child's head)

[Eleon BORLINI]

Hi @JKhai.1​ ,

thank you for sharing the video of your application, it's clearer now.

If you distance is only over 1-2m (maximum), probably a good choice could be the use of Bluetooth Low Energy (BLE): in this way you could directly interface your application with your PC (and probably there are also Labview drivers for the BLE component). From the "edge" side (the board inside the ball) you could use the BlueNRG-M2 for BLE transmission (datasheet:( it is equipped by a 10 bit ADC and you could check if this can be enough for your application.

-Eleon

[JKhai.1]

Thank you for your advice about using BLE.

I do need 12-bit ADC, so do you advise me to use the STM32WB series MCU to put it in the ball? Can I interface my application with my PC's Bluetooth with this MCU or do I need 2 of them?

What are your concerns about aliasing? My sensor has a response of 22kHz Max. So with sampling higher than 44kHZ would do it without a lowpass filter. Please correct me if anything's wrong.