Arduino UNO/Duemilanove 2dof firmware

[prilad]

Optoisolation is good to have but some times could be expensive...

http://www.digikey.com/product-detail/en/ADUM1400CRW/ADUM1400CRW-ND/612551, price $8.30, but SMD

Or these http://www.digikey.com/product-detail/en/AD260AND-4/AD260AND-4-ND/617060, price $61.60, PDIP package.

Either way these are not even in stock!!!!

Terrible story

http://www.digikey.com/product-detail/en/ADUM1400BRWZ-RL/ADUM1400BRWZ-RLTR-ND/624620
http://www.digikey.com/product-detail/en/ADUM1410ARWZ/ADUM1410ARWZ-ND/1523044

[tronicgr]

Its not only the available channels or the voltage rating...

Afaik the ADUM1400CRW is the only one rated for 45 MHz logic signal freq (90Mbps).

The ADUM1400BRW is rated only for 5 MHz logic signal freq (10Mbps), and the ADUM1400ARW for 1 MHz logic signal freq (2Mbps)... Kind of useless for fast and error free serial communications...


Thanos

[tronicgr]

Where I shop locally - RS Components.

Will these work. http://australia.rs-online.com/web/p/digital-isolators/7532226/

And this is only 500Khz rated (1Mbps) ... good for isolating simple on-off signals I guess, PWM maybe.


Thanis

[prilad]

Hi Thanos.

Once again I cannot agree with you

Its not only the available channels or the voltage rating...
Afaik the ADUM1400CRW is the only one rated for 45 MHz logic signal freq (90Mbps).
The ADUM1400BRW is rated only for 5 MHz logic signal freq (10Mbps), and the ADUM1400ARW for 1 MHz logic signal freq (2Mbps)... Kind of useless for fast and error free serial communications...

What do you say? what the "serial communications" do you mean? We are talking about isolation for DIR and PWM lines between Arduino and H-Bridge.

Or you think, that 1 MHz is very "slow" for this mission? But you use in your "optolink" (http://www.x-sim.de/forum/viewtopic.php?f=39&t=132&start=20#p978) optocouplers 4n35, which EIGHT times more SLOWLY than ADUM1400ARW.

In 4n35 Datasheet we can see, that rise time (Tr) for output pulse is 3.2 us and fall time (Tf) is 4.7 us.
It mean, what full pulse width can not be smaller then 3.2+4.7 = 7.9 us and max pulse "frequency" is only 127 kHz instead 1MHz for ADUM1400ARW

4n35_01.jpg (69.13 KiB) Viewed 7525 times

4N35 Rise and Fall times description

4n35_02.jpg (64.19 KiB) Viewed 7525 times

4N35 Rise and Fall times values

And 4n35 has propagation delay more then 5.7 us (Time-off delay) instead 100 ns (0.1 us) for ADUM1400ARW or 65 ns for ADUM1410 .

ADUM1410.jpg (34.15 KiB) Viewed 7525 times

ADUM1410 Propagation delay

Regards,
ALE

[tronicgr]

And I cannot agree more with you on the PWM signals...

But given the price, it would be cheaper to isolate the RX-TX signals from the serial port or the USB FTDI chip only. After all you just don't wan't the regenerative voltages or currents to damage your USB port on your computer or the motherboard, that costs more than just paying for replacing a microcontroller.

And isolating 2 lines (RX-TX) is simpler and more inexpensive than isolating 6 lines (for two motors). Imagine you had to isolate 6 motors!!!


Thanos

[prilad]

And I cannot agree more with you on the PWM signals...

Why? You made the same thing with "optolink" board. Isn't it?

But given the price, it would be cheaper to isolate the RX-TX signals from the serial port or the USB FTDI chip only.

Yes of course. But this thread about Arduino board. And this board in stock without RX-TX isolations. On my own controller board (not Arduino) I made isolation for RX-TX lines.

After all you just don't wan't the regenerative voltages or currents to damage your USB port on your computer or the motherboard, that costs more than just paying for replacing a microcontroller.

Yes of course. That is why you and I talk together about galvanic isolation.

And isolating 2 lines (RX-TX) is simpler and more inexpensive than isolating 6 lines (for two motors). Imagine you had to isolate 6 motors!!!

Yes of course. But this thread about 2dof firmware. And my H-bridge has only two control lines for motor.

Best regards,
Ale

[tronicgr]

I'm not here to argue. I'm just pointing out the correct use for the mentioned chips.

And of course the opto-isolator I designed can be used by this arduino 2DOF firmware as well. There is no argue that the 4n35 are enough for PWM signals.


Thanos

[prilad]

I'm not here to argue. I'm just pointing out the correct use for the mentioned chips.
And of course the opto-isolator I designed can be used by this arduino 2DOF firmware as well. There is no argue that the 4n35 are enough for PWM signals
Thanos

Yes. You are right.
I only want to say, that any way has alternatives...

Thanks and regards,
Ale.

[vicpopo]

Hi guy's,

Cool men ... I love your battle ... And I love that no one had lost ...

I learn a lot reading your posts.

Thanks to you.

Gilles

[ferslash]

dear Bob:

If you are able to wire up the whole thing and make it works... please, publish it, for a non electronic audience

this is a grate project... since it will brake the 200 usdlls barrier that pololu set for the non electronic guys


best regards guys...