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#63828 Deep dive on Asix AX88796C (Netduino 3 Ethernet's fancy new networking chip)

Posted by xc2rx on 08 August 2015 - 06:59 PM in Netduino 3

Hi Chris,


Thanks for the detail description of the new Netduino 3 ethernet chip. I like descriptive post like this one, keep it coming. I will play with the Ethernet version once I'm through with the Wifi version. BTW, haven't looked at the datasheet of the Ethernet ASIX, can it achieve true 100Mbps throughput (or close to it) at the C driver level? What's the maximum SPI speed? I know all these answers are in the datasheet but I'm short on time so haven't had a chance to read through it.

#63524 SPLIT: Integrated MAC and 10 vs 100 mbps

Posted by xc2rx on 14 July 2015 - 06:21 PM in Netduino 3

And btw, there are Ethernet versions of the Netduino3 here:


But still not possible to order from outside US, and the shop that should allow for that is nowhere to be seen.


Where can I find information about the Netduino 3 Ethernet board? I don't see it anywhere on the website. I want to see the schematic if possible. Thanks!

#63511 SPLIT: Integrated MAC and 10 vs 100 mbps

Posted by xc2rx on 14 July 2015 - 07:19 AM in Netduino 3

Hi Sukasa,

We have looked at making a Netduino 3 Ethernet PoE--but the added cost would put it out of the range of most makers. This is certainly something we could do for commercial customers in volume.
One good alternative I have seen for many maker applications is a PoE splitter.

What are you favorite things about Netduino 3 Wi-Fi?


Hi Chris,

If you guys do come up with a Netduino 3 with Ethernet, could you not use an EMAC+EPhy chip over SPI with a limitation of just 10Mbps like Netduino Plus 2? Could you guys use either the STM32F407VE or STM32F427VI that comes with a builtin EMAC then add an EPhy using MII/RMII to achieve 100Mbps performance speed? That would be awesome for many of the projects I work on. Let me know what to expect for the Ethernet version if possible.

#63510 Why not clock it @ 180MHz?

Posted by xc2rx on 14 July 2015 - 05:58 AM in Netduino 3

Just curious why the STM32F427 is clocked at 168MHz when it can achieve 180MHz? That can easily be done in the firmware by setting a couple more registers during the C-bootstrap/start-up code (without any modification to the existing hardware).

#63509 CC3100 external memory/flash requirements?

Posted by xc2rx on 14 July 2015 - 02:11 AM in Netduino 3

Damn I already bought some connectors from Mouser.

#63507 CC3100 external memory/flash requirements?

Posted by xc2rx on 14 July 2015 - 12:43 AM in Netduino 3

Nevermind, I found the JTAG connector part number in the schematic: FCI 20021121-00010C4LF

#63506 CC3100 external memory/flash requirements?

Posted by xc2rx on 14 July 2015 - 12:25 AM in Netduino 3

OH!!! I didn't realize that CC3100 and CC3100MOD are different. Now that makes complete sense. I just ordered a Netduino 3 from Amazon. By the way, will it be possible for you to provide the part number for the JTAG header? Just in case I want to debug the firmware using my Segger J-Link. Thank you!

#63498 CC3100 external memory/flash requirements?

Posted by xc2rx on 13 July 2015 - 10:11 PM in Netduino 3

Nevermind, I found the answers to my questions by looking through the CC3100.cs file. I'm surprised a link to the Netduino github repository isn't mentioned anywhere on the website but only in some of the Forum posts. 


Anyway, I found out that the TCP/IP stack that comes with the CC3100 isn't being used and that's why the external flash IC isn't needed. Instead, Netduino uses its own TCP/IP stack, the Netduino.IP. In my opinion, having the STM32F4 handles all the TCP/IP processing is a waste of RAM and CPU processing power. The CC3100 was designed to do all of those heavy lifting stuff so that even a small 8-bit ATMega MCU can make use of it. But it's understandable that sacrificing a bit of resources reduces the BOM cost of the board (by not needing that external flash IC). Might be more cost effective to use a different Wi-Fi IC minus the built-in processing power for handling a TCP/IP stack (since that's being handled by the host MCU). Either way, it is a very interesting approach how the CC3100 is being used in this case.


Also, the Netduino 3 was wired so that either the SPI host or UART host can be used to communicate with the CC3100. 

#63476 CC3100 external memory/flash requirements?

Posted by xc2rx on 13 July 2015 - 06:26 AM in Netduino 3

Here's a link to a similar question asked on the TI forum:


The TI employee that answered the question stated "So unfortunately you need the serial flash as some system and configuration files are required for proper operations." Hmmm....

#63475 CC3100 external memory/flash requirements?

Posted by xc2rx on 13 July 2015 - 06:19 AM in Netduino 3

In the CC3100 datasheet,, it says that the chip requires an external flash memory IC for its file system storage such as service pack file, system files, configuration files, certificate files, web page files, and user files. In the Netduino 3 Wi-Fi schematic, I do not see any external flash IC connected to the CC3100 IC. How is this possible?


If I have to guess, the CC3100's file sytem is probably stored in one of the 2 flash banks of the STM32F427. If that is true, then there must be a software layer running on the STM32F427 emulating an external flash IC supporting the required commands. But that's just a guess, can't really tell unless the firmware source code is revealed.


You can read about the external memory requirements on pages 29 - 30 in the datasheet.



Another question, is the STM32F427 talking to the CC3100 through SPI or UART? In the datasheet, it mentions that SPI can achieve up to 20MHz data transfer speed when UART can only do 3Mbps baud rate max. Giving the fact that the CC3100 can achieve a TCP throughput of up to 13Mbps and UDP up to 16Mbps, it would only make sense to use SPI over UART. In the schematic, I see both SPI host and UART host connected from the CC3100 to the STM32F427. So not sure which interface is really being used unless the firmware source code is revealed.

#63473 firmware source code for Netduino 3 Wi-Fi and JTAG header part number?

Posted by xc2rx on 13 July 2015 - 05:39 AM in Netduino 3



Netduino 3 Wi-Fi seems to be a very interesting platform for any IoT projects. However, I checked in the download section and did not find the firmware source code for this platform. I would like to see the firmware source code if I'm going to use this in any professional project. 


Also, I haven't received my board yet so it's hard to tell what kind of JTAG header would fit the JTAG pads. Would be great if a part number can be provided. Thanks!!

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