[Cryptech Tech] never do in software what can be done in hardware

[Benedikt Stockebrand]

Hi folks,

Fredrik Thulin <fredrik at thulin.net> writes:

>> Can you just read the least significant byte, or are they not even
>> double buffered at the byte level?
>
> AFAICT, the msp430 reads 16 bits at a time from memory. If I read a single 
> byte, it appears to read a word and discard half of it.

ouch; what does the documentation say on reading consistent data from
it?

>> That sounds pretty good; looks like we're getting close to what's
>> actually possible on the MCU side.
>
> Probably, for the ~20 MHz range. I'm slowly working on a new prototype with an 
> 84 MHz  STM32 CPU instead. Currently using the STM32F401 Nucleo evaluation 
> board. I'm quite curious to see what can be done with one of those, but I 
> don't have that much time available at the moment. Will keep you posted.

I have a somewhat similar idea over here: Use a GPIO pin on a Raspberry
Pi or BeagleBone Black or such.  It'll be ugly because it'll likely
involve writing a kernel driver to get the timing right, but well...
>> Right; I run the timer at clock speed and every sampling iteration takes
>> three clock cycles.  Since I only use the least significant bit anyway
>> this works out just fine.
>
> You're in luck the sampling takes an odd number of cycles ;)

Actually no: I checked the data sheet, checked the assembly code output
of the compiler, and then checked the result:-)


Cheers,

    Benedikt

-- 
Benedikt Stockebrand,                   Stepladder IT Training+Consulting
Dipl.-Inform.                           http://www.stepladder-it.com/

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