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I have an embedded sensor that has an Ethernet RJ45 cable/connector, which include Tx+, Tx-, Rx+, and Rx- signals that I need to convert to wireless. I need to embed it with the sensor and it needs to be small. I want to use a bridge like ConnectOne's Nano WiReach module. I haven't found anyone, including ConnectOne, that has an off-the-shelf RJ45 to wifi adapter based on Nano WiReach so I want to build one using one of their modules.

It's been suggested by their tech support that I use the module's RMII interface for this purpose, as I would save the hardware needed to add RJ45. However, I have not found any information on how to go from Tx+, Tx-, Rx+, and Rx- to the RMII signals. Please advise how this would be done, hopefully with minimal additional hardware. I'd like to solder the 4 ethernet wires on to the module.

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    \$\begingroup\$ Sounds like an access point. How is your project different from that? \$\endgroup\$ – jippie Aug 15 '14 at 21:14
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    \$\begingroup\$ 1 port wifi router... usb powered pocket/travel router like the asus WL-330NUL are cheap nd common, can be put in bridge mode, and that one is the size of a large flash drive. \$\endgroup\$ – Passerby Aug 15 '14 at 21:49
  • \$\begingroup\$ Do you have a datasheet for the sensor? \$\endgroup\$ – Armandas Aug 16 '14 at 8:58
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You need something like this:

enter image description here

Iogear NetShair IEEE 802.11n Ethernet Wireless Router @ overstock.com

Hypothetically, with that device you could do next:

First, connect it to your pc's usb a port and configure it appropriately (for example, simple bridge between rj45 and wi-fi (bridge mode), wi-fi acting as access point, wlan authentication method, ssid, password, etc...).

Second, connect your sensor to your pc's rj45 and configure it appropriately, at least, assign it a static ip in a new subnetwork not intersected with other(s) you use.

Third, connect the configured wi-fi router to your sensor by an Ethernet cable (RJ45-RJ45) and to an external USB 5V0 power supply directly.

Fourth, find the new wlan on your pc and assign the connection with a static ip address within the same subnetwork.

Firth, work with your sensor from your pc via ip.

If your sensor has 5V0 output, or corresponding circuits onboard, you can use (but do it safely) it for powering up the router.

About this:

It's been suggested by their tech support that I use the module's RMII interface for this purpose, as I would save the hardware needed to add RJ45.

IMO, your tech support proposed you to unsolder the Ethernet PHY off the module to free RMII circuits it was connected to. I think it's not a way because you probably will not find a Wi-Fi card with RMII (they are typically designed with SDCard or PCIe interfaces) and will not re-write the module firmware to support the card (Wireless Ethernet is times complicated than its wired bro).

Therefore if you would like to solder four wires, find 5V0 and GND at the module and, if any, solder a USB A socket with a wires to them, to connect the router's usb A plug in. There are only two wires needed, even not four :) versus about ten in RMII.

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  • \$\begingroup\$ This gadget could do it - well, almost. Unfortunately, the OP needs a Wifi client equipment, and this gadget is an AP-only equipment, at least according to its manual. \$\endgroup\$ – Laszlo Valko Jun 18 '15 at 18:43
  • \$\begingroup\$ @LaszloValko here men state that it can be the client (search for "Client Bridge"). \$\endgroup\$ – asndre Jun 18 '15 at 18:51
  • \$\begingroup\$ I'd guess that part is about the Zyxel box... \$\endgroup\$ – Laszlo Valko Jun 18 '15 at 18:59
  • \$\begingroup\$ @LaszloValko Yes, you are probably right. Do you think my "Something like this" in the beginning of the answer could not be related with the photo and link? Or could I assume that the OP'll understand the path (in general) i proposed to solve his problem? \$\endgroup\$ – asndre Jun 18 '15 at 19:08
  • \$\begingroup\$ Well, I don't know. But the proper google search keywords would be "mini wifi client ethernet bridge". This is a bit larger, but the manual explicitly shows how it could be connected to an AP: iogear.com/product/GWU627 \$\endgroup\$ – Laszlo Valko Jun 18 '15 at 19:19

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