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Microcontroller capabilities

Johnd001


I have been finding it hard to tell just how capable a given micro controller is.

I have an Arduino Mega but have not done any work with it.

The project I have in mind requires 2 24 bit counters. The micro controller need to be able to read the counters and divide one counter by the other. The dividend is used in a successive approximation to load a 16 bit counter which counts up or down to create an external trigger which should change the ratio between the first 2 counters.

All the counters need to be triggered enabled and cleared from external hardware logic.

Counter clock rate is 10MHz.

Do I need to build these counters from external chips or Is there a micro controller that could do the counting for me.

If I need to build them the only 8 bit try-state counters I see seem to be low volume parts like SN74AS867NTSN74AS867NT. Is there something better/ newer that I should be looking at for  a new desine?

 

While the counters are counting the system needs to be taking some analog reading. Is the Mega using the CPU while ADCs are done? how long does it take to read 1 analog pin? Are the analog pins multiplexed to 1 ADC or are there multiple ADCs on the chip.

 

How long does a 24 bit /24 bit divide take? Is there a Math library that would do the divide for me?

 

Should I be looking at a 32 bit controller that may to the math easier and have larger counters?

I am trying to get started in the right arena before I get too invested in any one controller.

Any help will be appreciated.

Thanks you

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  • 0

    Hello John,

     

    How often do you need to update the 16 bit counter - if the answer is not very often (eg < 1000 times  a second then you can certainly use a micro with the right timer/counter stuff - look at NXP and ST and pick an ARM (M0, M3 or M4 will all do) which has at least 2 x 32 bit counters and 1 x 16 bit counter.

     

    If you need to update very fast (eg at 10MHz rate (although this seems unlikely from your description)) you will need to use an FPGA.

     

    If you are making just one then consider using an ST32F4Discovery board (£10.13 from Farnell) which has the processor and debugging stuff at a pretty good price.

     

    You'll need to do your own investigating but this chip has the CortexM4 core that John mentioned so can probably sustain an update rate of the order of 100k per second.

     

    MK

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  • 0

    Hello John,

     

    How often do you need to update the 16 bit counter - if the answer is not very often (eg < 1000 times  a second then you can certainly use a micro with the right timer/counter stuff - look at NXP and ST and pick an ARM (M0, M3 or M4 will all do) which has at least 2 x 32 bit counters and 1 x 16 bit counter.

     

    If you need to update very fast (eg at 10MHz rate (although this seems unlikely from your description)) you will need to use an FPGA.

     

    If you are making just one then consider using an ST32F4Discovery board (£10.13 from Farnell) which has the processor and debugging stuff at a pretty good price.

     

    You'll need to do your own investigating but this chip has the CortexM4 core that John mentioned so can probably sustain an update rate of the order of 100k per second.

     

    MK

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