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Begginer with Cobra II


#1

I want to try Gadgeteer. I have chosen Cobra II as my first main board. I have few questions:

  1. It says there are 72 GPIO, how can I access them without using IO60P16?
  2. How should I connect supper cap to enable RTC when power is off?
  3. Is there still no support for VS2013?

#2

Welcome to the Forum.

  1. Cobra II is based on G120 SoM which has 72 GPIO. Some of them are used already onboard of Cobra II for SD, Ethernet, USB Host, … some for Display sockets …
    All remaining GPIO’s are available through the trough hole pads on the side.
    You should check the Cobra II schematics for that.

  2. The .Net Microframework SDK does not support VS 2013 so far. Theoretically you could compile it on your own, but that’s not the easy way.
    Also GHI ‘only’ supports NETMF 4.2 so far, so VS 2010 users are not cut out.
    This is usually no problem since thae framework changes from 4.2 to 4.3 are not that big. It was mainly released to support VS 2012.


#3
  1. Apart from 3V3, 5V and GND there are 36 pads on the side. Can I use all these 36 as GPIOs?

#4

yes, perhaps.

Sorry, I want you to realize that these IO pins may be used elsewhere as well, which is why I say perhaps. And that’s why you should look at the schematic to see what the pins are.

So let me also say, as far as Gadgeteer goes, the Cobra2 is NOT a good general purpose board. For a start, the Gadgeteer sockets on it only give you 6 connections - RGB for a screen (or general purpose, but not mixed), and 3 other sockets including one for touch when you use a screen. So if you’re really trying out Gadgeteer a different mainboard may be a better choice. Then, you need to think about how you’ll use the 35 IOs on the edge of the board (yes, there’s only 35 active IOs, and some of them are exceptionally special purpose like the RTC crystal pins!). You can’t just connect a Gadgeteer device on those pins as there is no virtual socket definition and you’d still need to use a breakout module to go from a mixed group of 0.1" header pins to a Gadgeteer socket; you could however extend the definition of the mainboard to make that work if you wanted.


#5

I don’t understand naming conventions used in that schematic (for example how should I know if I can use these as GPIO or not: [em]P0.0/CAN1_RD[/em], [em]P0.12/AD6[/em]). That’s why I wanted someone with deeper knowledge to have a look at this.

I have assumed that crystal is already integrated. If not, I would like to know what crystal and where to connect.

I have chosen this board after doing a quick comparison. Here are my notes:
Cobra II (Eco). Pros: not too expensive, integrated USB Client DP & SD Card modules, easily accessible GPIOs on the side. Cons: only 6 connections.
Cerberus. Cons: no RGB.
Hydra. Cons: no premium developer library, RLPLite, does not work in low temperatures.
Raptor & Spider. Cons: 2x more expensive than Cobra II (Eco).


#6

The one thing you didn’t talk about is whether you expect to use a lot of Gadgeteer modules or not - that’s why Spider/Raptor have the benefit, it’s super-simple to connect them. Don’t get me wrong, I have a Cobra2 WiFi sitting on the bench in front of me, it’s great, but it’s still not the be-all-of-Gadgeteer, which you mentioned is what you wanted to try out.

P0.0/CAN1_RD, P0.12/AD6 means the following:

This is a pin known as P0.0 on the processor. It has a secondary function of the Controller Area Network port 1 (CAN1) Receive Data (RD). The second pin is P0.12, secondary function is Analog-to-Digital channel 6.

While you won’t get the full 35 extra IOs from the edge connector, you will get a lot; but again, you’ll have those plus the ones on the Gadgeteer sockets you can reuse if you want. It has more than enough IOs for most purposes, but obviously less than the Raptor for example


#7

Also note the extender board that fits nicely if you need more sockets. And also adds the RTC socket which I personally feel is a must have…


#8

Ok, I can answer my own questions:

  1. Super cap can be connected as shown in Pic1. RTC_VBAT pin is on the side.
  2. There are Rev. A and Rev. B of Cobra II. It seems only the later one has crystal on board (Pic2). If you have older Rev., you can connect crystal as shown in Pic3. Pins are on the side.

Question is - how should I know which Rev. will I get before I place my order? Are part numbers the same for both Rev.?