need help in choosing a microcontroller

Can you please advise a microcontroller? It looks like nobody cares to list devices from competing manufacturers in the same document, providing both prices and features.

There is a project, I need to process data of frequencies 0.5-40 Hz. FFT and such. For FFT, the array will be 2^N. FFT will be used to eliminate the "high"-frequency noice (50+ Hz). (If you think that something would be an overkill, I will gratefully listen to your opinion.)

requirements on the MCU: - low power consumption - 12-bit ADC - room for FFT data, 32K or more of RAM. (Combinations like 32K + 2K also may be useful) - cheap: $1 optimal, $10 max. (or _a_bit_ more) - there are 2 modification of the problem, one needs plotting the form of the signal on the LCD display, another does not need any LCD; therefore, if some MCU that comes in two versions, one with LCD support, and another without, that would be great. - programming languages: at least C; Forth or C++ would be even better. Free compilers are preferable (that is, it's "free" when its cost is included into the chip cost) - word size: I will consider all options, 8/16/32/24.

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A crazy question fully deserving of the answer it got. get your project organised then ask a question that makes sence if you still need to.

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I don't want to be as rude as the other posts you received, but the questions you ask show that you have little experience with embedded CPUs or DSP. First, I seriously doubt that an FFT is the best way to implement a low pass filter. You have not said anything about the sample rate you are interested in using. This has an impact on the filter implementation. If you use a delta-sigma ADC with a single pole anti-alias filter, you can likely get away with no filtering in software. But then a 40 Hz low pass filter is pretty slow to try to do directly with the ADC filters. More likely you will end up with an FIR filter and a sample rate around 4 or 8 kHz. This will let you use a 1 pole anti-alias filter.

Regardless, it is unlikely that you need 32 KB of RAM for this. That brings us to the second way that you seem to be unprepared for this task. Rather than to try to select an MCU part based on the sparse information you have, you would do better to explore your algorithm/ software design on a PC first. This will let you make informed decisions about the tradeoffs of sample rate, ADC choice and software design. Then you can choose a part to implement the design.

On the other hand, there are a large number of devices out that that will meet the requirements you have laid out. The LCD support will limit your choices more than anything. But if you don't understand the things I have written above, it is not likely a good idea for you to proceed without help.


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I love this newsgroup.


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You should specify the volumes expected too.

It might be smarter to settle on ONE MCU, and have the LCD as a separate slave module - how much display bandwidth do you need ?


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Yes, IAR's Arm community website do this here:

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Go to chip selector and advanced search, i find it limited, could be better, but not too bad

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