[Oberon] WiFi module survey

D EMARD vordah at gmail.com
Sat Sep 26 10:27:51 CEST 2020

RMII is PHY level interface, so it doesn't "know" its MAC nor it adds
packet preamble or crc32 footer, which should
be implemented normally in the FPGA core logic or software.

ESP32 can be both client and AP so the same module serves both functions.
programmable in micropython so code is short and simple.
Maybe it could also run Oberon in far future... :)

ESP32-S2 is new series that has USB inside, so this would also be cool

Low-level electrical-only interface (resistors and diodes) for USB
D+ and D- directly to FPGA pins, minimalistic SIE interface in the FPGA core
and rest served by Oberon
would provide you both usb-device and usb-host function at speeds
up to 11Mbps (USB1.0 and USB1.1 devices) should also be good
enough , mouse kbd and other simple devices

Other USB chip interfaces like TUSB3340 could be used to reach USB2.0
speed but driving their modes and registers turns out to require longer and
more complex code than a simple SIE itself.

On 9/26/20, Joerg <joerg.straube at iaeth.ch> wrote:
> Wojtek
> I read your summary now. Wired Ethernet and WiFi define OSI layer 1 (PHY)
> and 2 (MAC). those two layers differ indeed: PHY obviously and MAC as well
> (Ethernet= collision detection, WiFi= collision avoidance)
> If I’m right, non of your mentioned chips exposes PHY and you have to
> implement MAC yourself. So, on OSI Layer 3 (IP) the difference is
> neglectable.
> From „socket“ (OSI layer 3 and 4) point of view there is hardly any
> difference.(you have to set SSID and channel and off you go)
> Ethernet is symmetrical (the same chip can be on both sides of the cable),
> but WiFi is assymmetrical (STA client and AP host). One choice you have to
> make: can the chip work in both modes? I mean, shall the Oberon system be a
> client-only or shall it be possible to be an access point as well.(assuming
> the SW for the AP side existed)
> I did not check the data sheets on the WiFi modes the chips support.
> BTW: The same choice has to be made for the USB chip; USB is asymmetrical as
> well. The USB on my board can be client-only. I can connect the board to my
> PC via USB but I will never be able to connect a USB mouse to my board. Even
> if the USB SW were ported to Oberon-07.
> br
> Jörg
>> Am 25.09.2020 um 01:33 schrieb Skulski, Wojciech
>> <skulski at pas.rochester.edu>:
>> Dear All:
>> I am sending this e-mail to a long list of names off-list because the list
>> server is not happy with attachments. Please feel free to post it to the
>> list if you can push the attachment through.
>> I was not able to do much real work because it is now grant reporting
>> season. But I did some research on WiFi. The results are presented in
>> several attached pages, starting on page 4. The other pages present my
>> thought and investigations on the Nordic radio module and Oberon software,
>> and some general remarks. All these pages are part of the RiskZero Rev 1
>> schematic. Since I am in no hurry, I keep pursuing information and adding
>> notes to the schematic package to be eventually released "really soon
>> now".
>> This investigation was triggered by Joerg remark that he could add WiFi to
>> the System, using Wiznet WiFi module. So I started digging in. The
>> findings were different from expectations. I found that the Wiznet WiFi
>> modules are rather poorly documented. A better choice could be the
>> Sparkfun module WRL-13678 with Espressif ESP8266 because there is more
>> information and code examples, although of mixed quality. The Espressif
>> tools seem good. Some of the Arduino community contributions seem sketchy.
>> The largest reservation against WRL-13678 is low speed.
>> The landscape of the WiFi modules is very mixed. There seems to be no
>> common denominator. Low performance application can be done with AT
>> commands. Both WRL-13678 and Wiznet modules support these commands. It is
>> not clear whether these two use an identical set of AT commands, or two
>> slightly different sets. Silicon Labs provides its own script BGScript.
>> Lantronix provides yet another command interface named LANCIS. If one
>> develops with one of those, one will be out of luck with the others.
>> Perhaps the most reasonable approach would be using the ATWINC15x0 module
>> from Microchip and define a common API with Wiznet W5500 because both
>> chips use a similar architecture. But even this is not clear because WiFi
>> is different from the wired Ethernet after all. It may not be warranted to
>> use the same driver if the details do not closely match.
>> All of these thought are expressed in the attached pages. I also collected
>> all the data sheets and app notes which I am referring to. The zipped
>> archive is 50 MB. I can send it to anyone who tells me how to share such a
>> large file. Having all these documents handy can spare quite a bit of
>> investigative work. If you want to receive these files, please send me a
>> dropbox link or something of this sort.
>> Thank you,
>> Wojtek
>> <WiFi_Modules_Overview-merged.pdf>
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