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revver11
(@revver11)
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Joined: 1 year ago
Posts: 9
2020-07-30 1:04 am  

I have built the arduino 433MHz receiver Bill demonstrated a little while ago but I have a different module (8pins) but it seems to work.

What I would like to do is modify the code in some way so that knowledge of the buffer size is not needed. I have some devices which use 433MHz to communicate and I would like to eavesdrop on them to figure out how they work etc.

Any suggestions?


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noweare
(@noweare)
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Posts: 14
2020-08-13 1:27 pm  

If you need variable size storage you will need to use dynamic memory allocation i.e. malloc, calloc functions from the standard library. I have heard the uno because of its small ram size (appox 2k bytes) does not do well using those functions. You may have to step up to an esp32 or stm32 which have a lot more ram.


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revver11
(@revver11)
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2020-08-19 3:51 am  

Thank you @noweare

More homework. I don't know malloc and calloc so I'll read up on them.

I'll try the uno first and hope I can trim it enough to fit. Once I know the buffer sizes of my devices, I can forget malloc and hard-code them and then take it from there with my experiments.

I was intending to get a mega and an esp32 soon, so maybe my hand is being forced. Thanks again.


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frogandtoad
(@frogandtoad)
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2020-08-19 5:25 am  

@revver11

Posted by: @revver11

More homework. I don't know malloc and calloc so I'll read up on them.

Look up the C++ 'new' and 'delete' operators too, for dynamic memory management.

Cheers!


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revver11
(@revver11)
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2020-08-19 8:48 am  

Aw! Even more homework. 🤔 

Thanks 👍 


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revver11
(@revver11)
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Posts: 9
2020-08-19 8:56 am  

I am looking in https://www.arduino.cc/reference/en/ but cannot find any of the keywords there.

Is there a better site to use?


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Pugwash
(@pugwash)
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Posts: 997
2020-08-19 11:34 am  

@revver11

 

This might be a good place to start your search for C++ commands not specified in the Arduino Language Reference.

https://www.tutorialspoint.com/cplusplus/index.htm


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noweare
(@noweare)
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Posts: 14
2020-08-19 2:20 pm  

Malloc, calloc etc... are from the C standard library, you will not find them in the arduino reference section. If you want to practice with how to use them I would recommend using an IDE like CodeBlocks or Eclipse set up for C/C++, not the arduino IDE. It will save you time, plus those environments normally have a debugger so you can step through your code. Once you understand then try it in the arduino IDE.


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revver11
(@revver11)
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Posts: 9
2020-08-20 1:51 pm  

@pugwash @noweare

Good advice both. Thank you.

So far I haven't been able to get the time to take it further. Just when I thought I could move ahead, life had other ideas. Ah well, the weekend approaches.

 


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noweare
(@noweare)
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Posts: 14
2020-08-20 5:12 pm  

@revver11 Yeah, I have about 4 unfinished projects I need to button up. Hard for me to

focus on one thing.


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