5 V tolerant:
It is obvious that we are in a transition phase between 5 Vlogic and 3.3 V logic.
It is obvious that we have to connect 5 V IC to other 3.3 V IC
It is obvious that we begin to enter a new phase where the circuits are supplied with 2.5 V.
For me it is obvious that circuits must at least accept two Vcc voltage .
Higher current.
I do not know how you work, but personally as a former analog electronics developer I have no difficulty to build my own "shield",
For me the first criterion is price : sometimes due to large volume effect it is better to buy ready made, sometimes not.
Common shields are designed for beginners so they incorporates all power interface and often there is no current problem. In those I do, I put the power interface only if necessary.
Another point I refuse to work with the limits of the product so a micro that can be supplied only 6 or 8 mA does not suit me.
I protest against the 40 mA per output announced on Arduino's site.
These are Absolute Maximum Rating.
Atmel Normal conditions :
For Atmel there is four conditions to simultaneously satisfy:
no more than 20 mA by outputs
and no more than 150 mA per port in Source mode
and no more than 100 mA per port in Sink mode
and no more than 200 mA on Vcc and Gnd
Bandpass:
Have à look on the datasheet of the DUE micro. Atmel says for reducing the ringing, designer have to add a 38 ohms serial resistor and PCB track must be 50 ohms matched.
Also read application note : AN02 Atmel AT91-AT91 signal integrity product.
On the DUE board are the lines matched ?
Not obviously it is not possible to adapt 50 tracks to Zc = 50 ohms without use a 4 layers PCB.
Width of a 50 ohms matched line with 2 layers PCB is 3 mm and only 0.5 mm with a "classic" 4 layers PCB.
Consequently, with Atmel SAM IC, there will be excess ringing. The ringing amplitude will depend on the how the wiring is realized.
I prefer the ST solution which offer solution of increasing rise time and fall time of the signal which solve ringing.
I am not alone to be interesting by STM32
There is two threads in this forum :
STM32, Maple and Maple mini port to IDE 1.5.x
Reply 2599, vues 65 101
STM32 "for the rest of us"
Reply 54 vues 1 501