OpenWRT router WR703N smart home automation compared to Rasp

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OpenWRT router WR703N smart home automation compared to Rasp

Postby Squonk » Tue Jul 17, 2012 3:32 pm

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The TP-Link TL-WR703N is probably the cheapest and smallest Wifi-enabled Linux platform you can get: for $20 on eBay, you get a 57mm x 57mm x 18mm small box featuring an Atheros AR9331 Chipset (integrated Wifi+ AR7240 400Mhz CPU), 4 MB flash memory, 32 MB RAM and a USB 2.0 port that is able to run OpenWRT.

It is quite easy to connect a serial <=> usb converter to get bootloader/console access and have fun with it.

janisalnis wrote a very thorough Instructables on how the OpenWRT router WR703N smart home automation compared to Raspberry Pi:

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Check the up to date files on DropBox.

However, it looks like he is also trying to sell these instructions as an eBook on eBay for $2!?!
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Re: OpenWRT router WR703N smart home automation compared to

Postby Squonk » Wed Jul 18, 2012 2:52 pm

Here are some interesting hardware hacks for the TL-WR703N, from the OpenWRT forum:
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Re: OpenWRT router WR703N smart home automation compared to

Postby mikem » Wed Jul 18, 2012 9:15 pm

For some further hw/sw tricks google "minipwner build one"

Would provide a link, but too new of a user.

Link: http://www.minipwner.com/index.php/what ... -minipwner

Admin edit: link added
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Re: OpenWRT router WR703N smart home automation compared to

Postby Emeryth » Thu Jul 19, 2012 8:31 am

RAM can be upgraded to 64MB if you are not afraid of hot air soldering.
Just take out one chip from a 512MB DDR 333MHz SODIMM module and replace the one on-board.
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Re: OpenWRT router WR703N smart home automation compared to

Postby Squonk » Thu Jul 19, 2012 1:32 pm

Emeryth wrote:RAM can be upgraded to 64MB if you are not afraid of hot air soldering.
Just take out one chip from a 512MB DDR 333MHz SODIMM module and replace the one on-board.

Yes, more details on the compatible SDRAM chips can be found in the OpenWRT Wiki.

It looks like you can replace the 4MB SPI Flash by an 8MB (MX25L6445EM2I-10G SOP8), but this would require an SPI Flash programmer (BusPirate?) to backup and restore the Flash.

And you can also use GPIO7 and GPIO29 as a software I2C port by unsoldering the R15 and R17 pull-down resistors:

YvURR[1].jpg
GPIO7 and GPIO29
umX5V[1].jpg
GND and +3.3V
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Re: OpenWRT router WR703N smart home automation compared to

Postby wookie » Thu Jul 19, 2012 1:41 pm

Has anybody found a source for the Atheros AR7240 CPU and Atheros AR9331 Chipset found in this device? How did you track down the GPIO pins without the datasheet? I'm interested in using thei chip and chipset in my own design but it seems like this chip and chipset isn't available to "hobbyists" like myself.

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Re: OpenWRT router WR703N smart home automation compared to

Postby Squonk » Thu Jul 19, 2012 2:18 pm

You will NOT find any source for SoC including either Wifi or GPU like these, as these kind of chips are not available for retail: you need to contact the manufacturer with MOQ (Minimum Order Quantities) of 100.000s, at least...

As hobbyist, the only way to go is to find some easily hackable and cheap devices like this one and use them with mods.

As for the GPIOs, the Linux kernel is exposing the GPIOs under "/sys", so you can test them with the Shell by using "echo".

But it is one thing to have access to them from software, and one other to find were they are located on the board and for what purpose they have been used...
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Re: OpenWRT router WR703N smart home automation compared to

Postby Scorpia » Tue Aug 14, 2012 7:16 pm

i have just got one of these routers and damm they are tiny,

i have been thinking about the 8MB flash chip upgrade and i was wondering, do people think it would be possible to double stack the flash chips but connect the second chips chipselect pin to one of the spare gpio, allowing to use of both the original 4mb + the stacked 8mb chip?

i dont know much about how linux access's the flash chip so im not sure if it would be possible to mod the kernal to use the second cs pin,

what do people think?
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Re: OpenWRT router WR703N smart home automation compared to

Postby Squonk » Wed Aug 15, 2012 1:43 am

Welcome to the club!

Electronically, your proposal is nice, but I don't know how the CS pin is driven from the kernel driver: it may be at the lowest level by the SPI controller itself, or worse: this may not involve the CPU altogether but only the DMA engine...

We need to check into the SPI kernel driver.
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