From microsd in arduino (either in txt or csv file) to MIT

So what I would like to do is that for the MIT app to display the saved file from the microsd module in arduino. It will be sent via bluetooth HC-05. It is either in txt or csv file but temporarily, we have it in txt file but a csv file might help in labelling and separating the information as we have 5 infos to be read. I am kinda new to MIT and all there are no tutorial about it and I am just adjusting others tutorial to do what I want to do but to no avail, can't do it. I think TinyDB will help me with it but am not really sure how to do it. Here's the information inside the csv file if ever. Thank you.


Hello Jiiiru - welcome to the forum.

  1. You are able to read the microSD with the Arduino?
  2. Can you upload your Arduino Sketch (.ino) file please?
  3. What model is your Arduino, is it an UNO or an MKR Zero?
  1. Yes but there are times when the microSD is not being read, we tried using it with an adapter and it is fine but maybe just the wiring or the shield itself is somewhat defective reason why sometimes the arduino can't read the microSD.
  2. We just use the example datalogger in arduino.
  3. For testing, we use UNO R3
    So far this is what I am following but we so far only one label has displayed and the other is not appearing.
    App inventor 2 : Receive Multiple data from Arduino via Bluetooth - YouTube
    Also, since we want to store the receive file into the mobile application, I tried TinyDB but am still learning since I can't understand it so far.

Yes, but you need to upload the .ino file you have, we can't go chasing around for the information, we have others to help too.

I can tell you that the intermittent failure is probably caused by insufficient power.

See my website: ProfessorCad: Tips & Tricks

There are 8 in the CSV, so it's probably best to read all 8 and then exclude the ones you don't want in the App.

Pins used,
RX - 3
TX - 2
5V - 5V
for the datalogger shield, it is in this .ino file.

data.ino (318 Bytes)

Apparently it is 8 I added two more. However, since I am just testing I did txt file first but it does not read anything at all...

.. how do you supply power to the Arduino?

That Sketch is unrelated to your task....

I connect it to my laptop and sometimes from a power supply (12V) with step down of 5V. I always get the failed card initialiation when it is connected in my laptop but there are times too when it can be connected and thats when I can proceed to check if there are readings in the app.

What is the amps output of the power supply @ 5 volts? - your laptop is not going to supply enough power to run your board successfully.

Manufacture and Model Name/Number?

Edit - usually a data logging shield saves data that is supplied via the Sketch, it is unusual to read the data. So how does the data get saved to the microSD card in the first place?

2A for the step down, 20A for the power supply, I used step down to not overcharge the arduino. I also tested my laptop and can supply 4.9V to the arduino.

this is the microsd card module that I am using:
Micro SD Card Module | Shopee Philippines

I also encountered being kicked out when paired in my MIT companion.

You need to test with an APK because the Companion does not know about your Shield.

SD Card Module is using SPI bus, which is handy because there is an Arduino Library which might work with it.

The max current acceptable for Arduino UNO is 1 amp. Your laptop probably cannot supply more than about 200mA, which is not sufficient.

The R3 board has a regulator:

You can use between 6V and 20V DC to power the board. It is recommended that you should not go below 7V to allow for the voltage drop across the power regulator. If you go too low then the regulator output might drop below 5V and this can cause issues with the boards operation.

It is also recommended that you do not go above 12V. The power regulator may over heat and cause damage to the board.

I see thank you will take note of this.

Yes I have searched about this. Can you help me with MIT? I am very confused now as to what to do. Currently eating dinner but will try running it with power supply than with my laptop.

I have a few things to do today so I will look into defining an ino file tonight (UK time). I think the only issue is reading the microSD card, sending that data via Bluetooth to the App is rudimentary, as is storing it.

You haven't told me how the data is stored in the microSD card?

Here is an example App Inventor project file that receives multiple values:

BT_Basic_Setup_ReceiveMulti.aia (8.4 KB)