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1. 

   manitou
   Member

   Maple has a software random() function for generating pseudo random numbers. Walter Anderson has developed an Entropy library for Arduino and ARM processors to use hardware timers and systick to generate stronger random numbers, see
   https://sites.google.com/site/astudyofentropy/project-definition/timer-jitter-entropy-sources/entropy-library

   As a proof of concept, I ported Walter's bit mixing functions into a maple sketch that uses the LSI clock and SYSTICK_BASE->CNT to generate random bits. The sketch which also uses the RTC lib is here
   https://github.com/manitou48/DUEZoo/blob/master/maplerng.pde
   A cursory analysis of a few megabytes of generated bits with diehard, rngtest, and ent, indicates the sketch provides "good" random bits.

   Running the LSI clock at a 10-ms interrupt rate yields a random bit every 10 ms. The DUE hardware TRNG can generate 32 random bits every microsecond. Some other bit-generation rates are at
   https://github.com/manitou48/DUEZoo/blob/master/RNGperf.txt

   Posted 1 year ago #
2. 

   gbulmer
   Moderator

   Interesting!

   Members of both STM32F4 and STM32F2 families have hardware random number generators (RNG) built in. They use analogue circuitry generating noise, to seed values.

   Posted 1 year ago #
3. 

   wandrson
   Member

   I am the author of the above library. When manitou contacted me about the possibility of porting the library to the maple boards, I looked at the datasheet for the ARM chip used by the board, the STM32F103RB, and could not find any mention of a hardware random number generator. If you can provide a reference to the device and perhaps some example code for it, I would appreciate it. The library already uses the internal hardware generator on the ATSAM ARM processor used on the Arduino Due, so it can easily be configured to do so on the Maple boards if such a device is available. If not, I have provided manitou with draft code to make use of potential jitter based random numbers on the Maple boards, using his test code as a base. Unfortunately I do not have any such boards available so I am unable to test it.

   If one or more users of the boards is interested in working with me to test the code and verify it, I can incorporate Maple support into the library.

   Posted 1 year ago #
4. 

   gbulmer
   Moderator

   wandrson - to avoid confusion, ...

   The Maple's STM32F103 does not have hardware random number generator manufactured in.

   However, there are several community designed boards at: https://github.com/gbulmer/openstm32hw
   which support the STM32F2xx and STM32F4xx microcontrollers. Those families of parts do have hardware random number generators manufactured in. Hence, if one wanted to consume random numbers, it might be worth looking at those families, and not limiting choice to Maple's STM32F103.

   I should have been clearer in my post.

   Posted 1 year ago #

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