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Topic: Mega 2560 USB (Read 941 times) previous topic - next topic

janleroux

I see that over the lifetime of the Arduino Mega, that it was changed not to use the FTDI USB-to-Serial driver chip, but that it instead started using ATmega8U2 and then ATmega16U2 for the USB to Serial conversion.

I am interested to understand what the reasioning could have been behind that? Cost, funtionality or future availability?

Regards
Jan

CrossRoads

Programmability of the USB interface for other functions.
Also cost, FTDI chips are $4.50 each.
$3.71, both at qty 1. Each lower in high qtys of course.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Course, CP2102 is $2.75, and there are other USB/Serial options as well.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

cmiyc


I see that over the lifetime of the Arduino Mega

Minor point: the original Mega used a ATmega1280.  The newer (since late 2010) Mega2560 uses an ATmega2560 and replaced the FTDI chip.


Cost, funtionality or future availability?

I guess you could think back to almost 3 years ago when the Uno was introduced and use a little imagination.  Thankfully, we have time on our side to support the following. 

The FTDI required drivers on every platform, was rising in cost as few devices needed a "RS232 interface", and was limited to being an USB to Serial device.  By moving to a microcontroller now only Windows requires a "driver" (not really), drops in cost thanks, and can be reprogrammed to any number of USB  devices.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

janleroux

Ok, so both cost, functionality future-proofness - makes sense.

But with the FTDI chip one could use their drivers and VID/PID. I read somewhere that you can only use the Arduino VID/PID when it is an official Arduino product. If you want to make your own spin-off board, then you have to get your own PID/VID?

Or is that only applicable to the Windows environment?

cmiyc


But with the FTDI chip one could use their drivers and VID/PID

All engineering decisions have trade-offs.  Eventually someone won't like the tradeoff.

Or is that only applicable to the Windows environment?

It is a requirement by the USB-IF that devices have their own VID and PID.  FTDI has opted to allow end-users to use the FTDI VID for their products, but require users to register for their a unique PID (through FTDI).

If you are selling a product, I can't see a valid reason why you wouldn't want to register your own VID with the USB-IF anyway.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

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