Cobra III Ethernet Connection

Archive
1

We’ve established internet communication with Cobra II boards but need to migrate to Cobra III or Panda III. As these boards do not have a ethernet connector (RJ45), it seems I could purchase a ENC 28 module from GHI that ties into a GXP Gadgeteer board, also purchased from GHI. This seems a roundabout solution, although easiest and reliable, but I’d just rather not go the gadgeteer route. Another option would be to buy a ENC28 module on eBay for less but need to understand how to communicate to the Cobra/Panda. Is it as simple as connecting to appropriate pins on the Cobra/Panda or is some additional software needed? Is there a description on how to make this connection? thanks for enlightenment.

2

Thanks, cyber, but what to look for on the schematics? is there a description on how to make this connection? I find a description for Arduino but nothing for GHI Cobra?

3

I dont think GXP can be used if you look at the U socket

[url]https://www.ghielectronics.com/downloads/schematic/GXP_Gadgeteer_Bridge_SCH.pdf[/url]

And compare to

[url]http://www.ghielectronics.com/downloads/schematic/Ethernet_ENC28_Module_SCH.pdf[/url]

You see you would have to use the CAN TD as CS COM TX a reset…

I would wire a breakout module and the ENC28

[url]https://www.ghielectronics.com/catalog/product/405[/url]

4

Thanks, David. I did find the suggestion to use the GSP bridge from post by Gus. Your suggestion to use a breakout module is appreciated but that would require purchasing the ec28 from GHI rather than the less expensive route with eBay? Still need to know which pins i’m looking for. i need to power the enc28, correct?

5

Hi, I did not try but I think it should be the same as for the WiFi Module (see this thread):
https://www.ghielectronics.com/community/forum/topic?id=23178&page=3


WiFiRS9110 netif = new WiFiRS9110(GHI.Pins.FEZCobraIII.SpiBus.Spi2, GHI.Pins.FEZCobraIII.Gpio.D51, 
      GHI.Pins.FEZCobraIII.Gpio.D50, GHI.Pins.FEZCobraIII.Gpio.D59);

Perhaps another option for you could be to use the Spider II Mainboard with Power Module an EthernetJ11D Module.

6

Yeah, it is probably the same. I’ll study away and hopefully give a ENC28 a try. Thanks for your help. If we can get it to work I’ll document.

7

After a little study of schematics I see SPI2 module broken out as D57, D55, and D53 on the 40 pin female header on the Cobra III. However, I can’t seem to find where the G120 pins 1_9, 1_10 and 2_11 (which are connected to the ethernet module on the Cobra II Net) lead to on the Cobra III. Can anyone provide some more (specific) enlightenment?

RoSchmi’s example above shows D51, D50 and D59, which are shown as P0_5 CAN2.TD, P0_4 CAN2.RD and P4_28 COM4.TX on the Cobra III’ 40 pin header. These may or may not be the pins to use,

8

@ Matt5 - You can connect the ENC28 module to either of the SPI busses and use any available GPIO on the FEZ Cobra III. You do not need to mirror what the FEZ Cobra II did. When you construct the ENC28 class you tell it which pins you picked.

9

Thanks very much, John. Hence, in terms of software:

WiFiRS9110 netif = new WiFiRS9110(
    GHI.Pins.FEZCobraIII.SpiBus.Spi2, 
    GHI.Pins.FEZCobraIII.Gpio.D51, 
    GHI.Pins.FEZCobraIII.Gpio.D50, 
    GHI.Pins.FEZCobraIII.Gpio.D59, 
    clockSpeed);

I see the ENC28 Module using the Gadgeteer socket has 4 pins + the SPI set + VCC/5V/GND while the software seems to need 3 pins. I suppose one of the pins on the Gadgeteer socket is not used. If i"m on the right track, which pin on the Gadgeteer socket is not used?

I’m trying to understand all of this in order to not use GHI’s ENC28 module as USPS now charges $34 (US) to mail it to Canada where it was $8 last month, making GHI very costly for a Canadian address.

10

@ Matt5 - On the Gadgeteer socket: pin 3 is interrupt, pin 4 is reset, and pin 6 is SPI chip-select. Pin 5 is not used.

11

thanks, John. Now I’m not sure what “SPI chip-select” on Pin 6 is and how the three SPI pins are given to the software. I assumed whatever three SPI pins one chooses to use are attached via pin 7,8 & 9 on the gadgeteer socket. But then the call to new WiFiRS9110() can be passed GHI.Pins.FEZCobraIII.SpiBus.Spi2 rather than the three SPI2 pins. Does “SPI chip-select” refer to this Spi identification? If so, does low voltage (0) indicate Spi1 and high voltage (1) indicate Spi2? But then wouldn’t this be redundant if the actual pins are available at 7-9 but maybe needed for the call to WiFiRS9110()? If not, what does “SPI chip-select” refer to? Obviously confused.

12

Good stuff from Wikipedia–thanks, Cyber. So with clk the clock output from the master, CS, a.k.a. SS (Slave Select), seems to identify the slave in case of multiples–set low if one slave which would be the case with a RJ45.

13

yep, largely. SPI is a shared bus, so the intent is you use MISO, MOSI, CLK as common pins on the bus, for say four devices. Then you only need 4x individual pins for CS on each slave on the bus so the master can tell the slave hey, listen up. If you don’t share the bus you may not technically need this to be an IO pin, but it’s just easier to do so.

14

Brett:

Cool.

15

BTW, Another look at the schematic revealed where these G120 pins are broken out on the Cobra III:
P1_9: D9
P1_10: D8
P2_11: MicroSD CDN
But the point is learned that any three GPIO pins can be used rather than these. (as long as the software takes the three.)