Brainstorming Improving Next Version Of digiX Board

[gogol]

I open this thread, as digging into the digiX, I stumple upon some questions, which could be improved or extended in one of the next releases.
For an better overview in cases this thread grows over the month, I recommend the following edit rules:

• Post for each new suggestion one message with own subject
• Discussing pros/cons reply to the right subject.

[gogol]

As the SAM3X8E allows NRST or NRSTB for reset, make both available.
Right now only NRSTB is available. :-(
If both are available, mark them different on the PCB.
See:

• http://digistump.com/board/index.php/topic,1211.msg5374.html#msg5374
• http://forum.arduino.cc/index.php?topic=160361.0

[gogol]

Looking to the Electrical Characteristics, the currently used LQFP allows for a max of 130mA on all IOs. The LFBGA allows for 150mA, which might be a better choice, as the digiX allows for much more IO-pins than the DUE.

[gogol]

The Due has two crossconnections on digital PIN 4 between PC26 and PA29  and on digital PIN 10 between PC29 and PA28.

Those connections are at least for certain projects counterproductive.  So it might be an advantage, there could be two additional pins for PA28 (digital 77) and PA29 (digital 87) and an solder bridge for both crossconnections, which could be opened, if needed.

(http://forum.arduino.cc/index.php?topic=205569.msg1512787#msg1512787)

[gogol]

To allow Pin 52 (PB21) to be used as fourth serial or A12, when using nRF, there should be an jumper, allowing the usage of an alternate PIN for chip-select on the nRF.
Probably PB23 (Pin 102) would be a good choice.

[gogol]

The labels for the AREF bridges could be made more clear, see example:

[gogol]

The ERASE-Pin should be available for alternative programming connections

[dfarrell]

Break out the backup voltage pin (VDDBU) to a connector suitable for a battery.

[gogol]

The Due has two crossconnections on digital PIN 4 between PC26 and PA29  and on digital PIN 10 between PC29 and PA28.

Those connections are at least for certain projects counterproductive.  So it might be an advantage, there could be two additional pins for PA28 (digital 77) and PA29 (digital 87) and an solder bridge for both crossconnections, which could be opened, if needed.

(http://forum.arduino.cc/index.php?topic=205569.msg1512787#msg1512787)

The reason for those cross-connections was the idea, to be backwards compatible to 8-bit Arduinos and have PWM and SPI-chip select on one pin.
As PWM is generated via the TIO Timer-Functions and none of those had chip-select functions, the Arduino developers decided, to combine two cpu pins.

With that background I think, it would really make sense, to lead both cpu pins to individual pins and make it selectable with solder-bridges, which function goes to which pin.

[dfarrell]

How I see it the WiFi is on Atmel TXD0 and RXD0.  For hardware handshake to be effective it must use the RTS0 (PB25) and CTS0 (PB26). If this is done, then the PDC (DMA) will function with the handshake. Other means of emulating the handshake cannot respond (character by character).

[dfarrell]

If would be nice to support USB host without some odd cable.  Use the AB connector like the Due does.

[gogol]

I don't understand that point.  From my understanding both devices, the DigiX and the Arduino DUE have both an 5-pin micro-AB socket with the UOTGID (pin4).

To flash the devices or to use the programmed device as a peripheral device (e.g. act as keyboard, mouse, CDC-COM-port, ...) you need to use a standard AB-cable with a micro-B plug pointing to the DUE/DigiX.

When using USB-OTG where the DigiX or the Arduino DUE acts as master, and the application wishes to use a connected keyboard, mouse, disk, ...  you need to use an OTG-cable.
This cable has an special micro-A plug, pointing to the DUE/DigiX; on that plug the UOTGID-pin (4) is grounded, which is the trigger, that USB goes to host mode.
On the other end of that cable can be either an type B plug, which will connect direct to the peripheral or there can be an normal type A socket, where a normal A-B cable can be plugged in for connecting the peripheral device.

I have used both cable types with my DigiX, the adapter-cable and the straight OTG-cable.

However I may have missed some detail.

I have right now no access to an DUE, but I will check both ways there, as soon as I will get the next into my hands.

[gogol]

One additional point:

from Wikipedia:
The UOTGID-pin can also have three additional ID pin states with resistance values of 124 kΩ, 68 kΩ, and 36.5 kΩ, with respect to the ground pin. These permit the device to work with a USB Accessory Charger Adapter which allows the OTG device to be attached to both a charger and another device simultaneously. These three states are used in the cases of:

• A charger and either no device or an A-device that is not asserting VBUS (not providing power) are attached. The OTG device is allowed to charge and initiate SRP but not connect.
• A charger and an A-device that is asserting VBUS (is providing power) are attached. The OTG device is allowed to charge and connect but not initiate SRP.
• A charger and a B-device are attached. The OTG device is allowed to charge and enter host mode.

That could be worth investigating further, if the SAM3X8E is supporting those states.  I found nothing about it in the documentation.

[dfarrell]

The connectors are physical different shapes.  One is rectangular, the other is trapezoidal.

[gogol]

The connectors are physical different shapes.  One is rectangular, the other is trapezoidal.

Thanks for that information.  I was not aware of that difference.   "USB micro AB-receptacle" is the magic search-term, which returns immediately enough examples.
Neither the English nor the German Wikipedia article has pictures in it :-(