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Topic: Two arduino boards with a single SD card (Read 695 times) previous topic - next topic

muscionig

Hello,
I need to connect two boards to the same SD card. I have looked at the previous topics about that questions and always this configuration is really not recommended. However, I am forced to do this. I have already implemented a locking system between the two boards.

The idea would be to close everything related to SPI on a board, send an unlock to the other one and open the SPI connection. Obviously, this would be done bidirectionally, always having one board at a time able to write the SD. I cannot use a multiplexer, and I cannot transmit the data between the two boards and let one of them writing the SD.

I noticed that I should use the SdFat library as the SD has a problem with multiple begin().

Have you got any advice, something I am loosing in my design?

Thank you.

Nick_Pyner

something I am loosing in my design?
Quite likely a rational reason. Some explanation of why you have these restrictions on what you can and cannot do might be in order, and most particularly, who imposed them.

muscionig

Quite likely a rational reason. Some explanation of why you have these restrictions on what you can and cannot do might be in order, and most particularly, who imposed them.
I have this constraint as I have a limited area for our system. I will use two microcontrollers that are compatible with arduino library. Thus, I will have no more space for an additional component, like a multiplexer.
Moreover, I cannot transmit the data to a single board as the power consumption of this action will be higher than connecting directly to an sd.
As the microcontrollers are not very powerful I need to do different things on the two boards, thus, sending the data to a board will stop the computation in this board.

I can connect two more serials for handling the locking, as adding some cable will not be a problem.

Thank you.

Nick_Pyner

Nothing concrete then, no numbers, no real hardware descriptions, not even an indication of what the project is about, just vague ideas of some nebulous secret, and poorly explained at that.

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