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A couple of things 43s related
02-26-2015, 10:40 PM
Post: #21
RE: A couple of things 43s related
(02-26-2015 07:32 PM)rprosperi Wrote:  Someday Walter, you must document the full Naval taxonomy of HP Calculators. For example, what is the 34S? Destroyer? E-Boat?

Trojan horse? Submarine? Life boat?

Marcus von Cube
Wehrheim, Germany
http://www.mvcsys.de
http://wp34s.sf.net
http://mvcsys.de/doc/basic-compare.html
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02-27-2015, 08:48 PM
Post: #22
RE: A couple of things 43s related
(02-26-2015 09:43 PM)MarkHaysHarris777 Wrote:  Whoa... definitely worth looking into... I was not aware of the 'Teensy' category either. That little fellow would fit anywhere; question is whether it has enough pins (although, the idea of using more than one for parallel processing and process management is more feasible with low power using two or three of these!). Thanks for the tip. Have you programmed the 'Teensy' ?

Yes, I too was very impressed when I saw Teensy 3.1.

I'm quite sure one teensy alone could do the job, from memory (256k flash & 64k Ram) or performance point of vue. 34 digital I/O pins shall also be sufficient, especially if you consider some SPI LCD driver (only 3 pins needed) , some lines for keyboard matrix (with or without a 3 to 8 decoder), and plenty remaining I/O for, hum, maybe HPIL like interface ?

Actually, I'm using a Teensy 3.1 to emulate a generic HPIL device on Jeff's EMU41. So far I managed to have some HPIL storage and digital I/O & PWM outputs.

I use it with the Arduino / Teensyduino IDE on Windows, not perfect, but usable.
It has many libraries available, I'm using sdfat for the storage & scoop for cooperative multitasking.

Regards.
Jean-Christophe.
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03-01-2015, 01:37 AM (This post was last modified: 03-01-2015 06:22 AM by BarryMead.)
Post: #23
RE: A couple of things 43s related
(02-26-2015 07:27 PM)jch Wrote:  Marcus,

Maybe a Teensy 3.1 could do the job ? It's tiny, quite cheap, low power and have horse power.
https://www.pjrc.com/teensy/teensy31.html

Regards.
Jean-Christophe.
I have one of these Teensy boards. I wrote a few test programs on it to confirm that the USB interface is fast and reliable, then I just put the thing into my toolbox for future projects. I don't remember that it was particularly low power, except in sleep mode, but it certainly is powerful. It uses an ARM Cortex-M4 MK20DX256 32 bit processor running at 72 MHz. At that clock speed it will use quite a bit of power unless it is sleeping. With all internal peripherals turned on it consumes about 31 mA operating, and you need to add any current consumed by driven outputs to that total. While it is sleeping with all internal peripherals turned off, it consumes .61 mA. So if you operate one of these with batteries, you would want to use AA cells not coin cells. With 2500 mAH AA cells you could get about 80 hours of program running time, or about 1/2 year of off (Sleep) time.
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03-02-2015, 06:10 AM
Post: #24
RE: A couple of things 43s related
(03-01-2015 01:37 AM)BarryMead Wrote:  
(02-26-2015 07:27 PM)jch Wrote:  Marcus,

Maybe a Teensy 3.1 could do the job ? It's tiny, quite cheap, low power and have horse power.
https://www.pjrc.com/teensy/teensy31.html

Regards.
Jean-Christophe.
I have one of these Teensy boards. I wrote a few test programs on it to confirm that the USB interface is fast and reliable, then I just put the thing into my toolbox for future projects. I don't remember that it was particularly low power, except in sleep mode, but it certainly is powerful. It uses an ARM Cortex-M4 MK20DX256 32 bit processor running at 72 MHz. At that clock speed it will use quite a bit of power unless it is sleeping. With all internal peripherals turned on it consumes about 31 mA operating, and you need to add any current consumed by driven outputs to that total. While it is sleeping with all internal peripherals turned off, it consumes .61 mA. So if you operate one of these with batteries, you would want to use AA cells not coin cells. With 2500 mAH AA cells you could get about 80 hours of program running time, or about 1/2 year of off (Sleep) time.

I'm definitely going to play with one of these soon. I am suspicious that this 'teensy' board will have speed stepping or at least a way to reduce the main clock (the WP34s 'SLOW' mode) which will reduce the current drain; most of the time we really don't need the ARM to be running so dang fast that it sucks our batts dry...
i don't mind using the ubiquitous 9v batt, nor lithIon... doesn't have to use coin cells (that seems to be an expected paradigm now with HP calc users.

Cheers,
marcus

Kind regards,
marcus
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03-02-2015, 01:49 PM
Post: #25
RE: A couple of things 43s related
(03-02-2015 06:10 AM)MarkHaysHarris777 Wrote:  I'm definitely going to play with one of these soon. I am suspicious that this 'teensy' board will have speed stepping or at least a way to reduce the main clock (the WP34s 'SLOW' mode) which will reduce the current drain; most of the time we really don't need the ARM to be running so dang fast that it sucks our batts dry...

All ARM chips have variable clock speed, you can program it at will on software (look for PLL control registers on the SoC datasheet).
Also, while waiting for the user to press a key (which in a calculator will be 99.9% of the time), use the "Wait-for-interrupt" CPU instruction, which freezes the CPU to a very low-power state until an interrupt is triggered.
That alone can save a lot of power.

Claudio
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03-02-2015, 09:09 PM (This post was last modified: 03-02-2015 09:10 PM by jch.)
Post: #26
RE: A couple of things 43s related
Barry, I must agree. Compared to the intake of HP-25C processor (1µA sleeping...), Teensy seems (very) greedy.

Anyway, things are evolving:
this: https://forum.pjrc.com/threads/23660-Low...e-Teensy-3
this: https://github.com/duff2013/Snooze
and this: https://forum.pjrc.com/threads/27675-Red...Teensy-3-1 may lead to a better autonomy.

And as Claudio suggests, using a lower processor speed and sleeping whenever possible will further improve the runtime.

Regards.
Jean-Christophe.
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03-02-2015, 09:40 PM (This post was last modified: 03-02-2015 09:42 PM by BarryMead.)
Post: #27
RE: A couple of things 43s related
(03-02-2015 09:09 PM)jch Wrote:  Barry, I must agree. Compared to the intake of HP-25C processor (1µA sleeping...), Teensy seems (very) greedy.
The processor is a POWERHOUSE it is designed for HIGH POWER 100 mA sink or source outputs. It was never intended to be a low power device. Since it gets up to half an amp of continuous power from the USB port, saving current was never a design consideration for the teensy.
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