DM42 News
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03-13-2018, 03:46 AM
Post: #421
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RE: DM42 News
(03-12-2018 06:43 PM)grsbanks Wrote:(03-12-2018 04:37 PM)eulerfan Wrote: I just had a thought. I suppose the operating system (Free42 + device drivers) is also stored on that flash drive. Good to know, thanks. I searched for the STM32L476 and found its specifications here: http://www.st.com/en/microcontrollers/stm32l476rg.html That is one loaded chip! It seems the DM42 doesn't even need all the hardware features. I would be tempted to use things like the analog/digital converter if the battery were bigger. Quote:(03-12-2018 04:37 PM)eulerfan Wrote: Is there a way to do a checksum or CRC on the OS to verify that it's intact? Great, it seems the designers anticipated my concerns. That's reassuring. Quote:(03-12-2018 04:37 PM)eulerfan Wrote: Does the DM42 have a reset button that forces a reboot? Makes me wonder if it's possible to download native ARM code into the DM42. I bet there's lots of room on the STM's 1 MB flash. |
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03-13-2018, 04:06 AM
Post: #422
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RE: DM42 News
(03-13-2018 03:46 AM)eulerfan Wrote: Makes me wonder if it's possible to download native ARM code into the DM42. It certainly is possible, all you need is a suitable compiler and an ST-LINK/V2 which can be had inexpensively if you shop around. Try CC41! |
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03-13-2018, 06:33 AM
Post: #423
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RE: DM42 News
(03-13-2018 03:46 AM)eulerfan Wrote: That is one loaded chip! It seems the DM42 doesn't even need all the hardware features. I would be tempted to use things like the analog/digital converter if the battery were bigger. Actually, the DM42 uses that already to measure battery voltage. That is actually accessible to the user in one of the virtual variables: RCL "Vbat" (03-13-2018 03:46 AM)eulerfan Wrote: Makes me wonder if it's possible to download native ARM code into the DM42. I bet there's lots of room on the STM's 1 MB flash. That 1MB flash is already about 85% full... |
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03-13-2018, 06:47 AM
Post: #424
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RE: DM42 News
(03-13-2018 03:46 AM)eulerfan Wrote: Good to know, thanks. I searched for the STM32L476 and found its specifications here: It even has a true random number generator. Anybody knows if it is used in the RAN# function? Regards. |
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03-13-2018, 06:49 AM
Post: #425
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RE: DM42 News
As far as I know, it uses the RNG in Free42.
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03-13-2018, 09:14 AM
(This post was last modified: 03-13-2018 09:14 AM by pier4r.)
Post: #426
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RE: DM42 News
(03-13-2018 03:46 AM)eulerfan Wrote: Good to know, thanks. I searched for the STM32L476 and found its specifications here: How much documentation for a chip. I never looked around chips (well, only briefly) but having that much of a documentation for a product should be amazing (if the contents are useful). Plus they even benchmark the thing themselves instead of leaving you in the dark. I did not know the coremark. https://www.eembc.org/coremark//index.php . One has even quite some references in the benchmark, as there are well known cpu, as the pentium 100. The pentium 100 for example has 213 coremarks vs the declared ~270 of the STM chip. Wikis are great, Contribute :) |
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03-13-2018, 01:21 PM
Post: #427
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RE: DM42 News | |||
03-13-2018, 08:05 PM
Post: #428
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RE: DM42 News | |||
03-13-2018, 11:45 PM
Post: #429
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RE: DM42 News
I'd trust the built in RNG more but I'd still over sample and run the output through one of the built in cryptographic digests. The output would be very fast and likely completely random.
Pauli |
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03-14-2018, 05:35 PM
(This post was last modified: 03-14-2018 05:35 PM by ijabbott.)
Post: #430
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RE: DM42 News
(03-13-2018 06:49 AM)grsbanks Wrote: As far as I know, it uses the RNG in Free42. Although presumably it would only use the hardware true RNG to generate the initial seed the software PRNG (when the user specifies 0 as the initial seed). I wonder if it waits for two values from the RNG since it takes a finite time to produce a 32-bit true random value, and the software PRNG seed is more like 46.5 bits (14 decimal digits)? |
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03-14-2018, 07:41 PM
Post: #431
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RE: DM42 News
(03-14-2018 05:35 PM)ijabbott Wrote:(03-13-2018 06:49 AM)grsbanks Wrote: As far as I know, it uses the RNG in Free42. On 0 SEED, the DM42 seeds the RNG using the real-time clock. The hardware RNG is not used. |
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03-15-2018, 12:09 AM
(This post was last modified: 03-15-2018 12:17 AM by eulerfan.)
Post: #432
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RE: DM42 News
(03-13-2018 06:33 AM)grsbanks Wrote:(03-13-2018 03:46 AM)eulerfan Wrote: That is one loaded chip! It seems the DM42 doesn't even need all the hardware features. I would be tempted to use things like the analog/digital converter if the battery were bigger. Good enough. I wasn't planning to use the A/D converter anyway, as keeping the calculator on would drain the battery. Quote:(03-13-2018 03:46 AM)eulerfan Wrote: Makes me wonder if it's possible to download native ARM code into the DM42. I bet there's lots of room on the STM's 1 MB flash. Darn. That idea goes out the window. I was hoping that function plotting would go faster in native code. (Yes, I saw the Youtube video of a 3D plot.... the speed wasn't great.) |
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03-15-2018, 12:13 AM
Post: #433
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RE: DM42 News
(03-13-2018 04:06 AM)Craig Bladow Wrote:(03-13-2018 03:46 AM)eulerfan Wrote: Makes me wonder if it's possible to download native ARM code into the DM42. Hmmm... that's a thought. Thanks. |
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03-15-2018, 12:30 PM
Post: #434
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RE: DM42 News
(03-15-2018 12:09 AM)eulerfan Wrote: I was hoping that function plotting would go faster in native code. (Yes, I saw the Youtube video of a 3D plot.... the speed wasn't great.) You probably wouldn't get much of a speed-up anyway. The overhead from executing 42S programs is quite small, particularly when compared to CPU-intensive floating-point calculations. The most effective ways to speed up that demo are: (1) plug in a USB power source to increase the CPU speed from 25 to 80 MHz, and (2) compile native code with single-precision binary floating point, which the CPU supports in hardware. Of course (2) also requires extensions to the Free42 part of the firmware, to add support for loading and executing native code objects. Or some even more drastic change, like ditching the DM42 firmware altogether and running a minimal Linux instead. |
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03-15-2018, 02:55 PM
Post: #435
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RE: DM42 News
(03-15-2018 12:30 PM)Thomas Okken Wrote:(03-15-2018 12:09 AM)eulerfan Wrote: I was hoping that function plotting would go faster in native code. (Yes, I saw the Youtube video of a 3D plot.... the speed wasn't great.) Perhaps the plotting function could take an algebraic formula (like "x^2 + 5") and use hardware floating-point to evaluate it. That should be much faster than repeatedly executing a 42s program using decimal arithmetic. |
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