I managed to lock myself out of my router. I think it must the firewall rules I changed. I can now only connect to it via serial terminal. On the website it says I need a 3,3v ttl serial cable. According to the tutorial it's self powered so I only need txd,rxd and gnd. Is it possible to use my ft232rl breakout from my arduino?

I was thinking of feeding the ft232rl 3.3v on vcc and vccio. Then rxd and txd should equal to 3.3v when driven high yes? The voltage am measuring out of the breadboard psu is 3.68 but that doesn't matter does it? I don't have anything else that outputs close to 3.3v.

Here's a picture of what I need


Picture of how it need to be connected to my router http://www.myopenrouter.com/article/19840/How-to-Debrick-Your-NETGEAR-WNR3500L-Using-Ubuntu-10.04-Lucid-Lynx/?textpage=2

This is how I intend to wire it. Oviously with txd,rxd and gnd connected to the router.

enter image description here

  • \$\begingroup\$ I don't know if this helps, but the router has a 3.3V power supply pin on its header: wiki.openwrt.org/toh/netgear/wnr3500l I also don't know how the "ft232rl breakout" you are talking about is wired, is there a schematic or is this just the bare chip on an adapter? \$\endgroup\$ – 0x6d64 Dec 10 '11 at 9:38
  • \$\begingroup\$ it's a bare chip on sparkfun breakout board. The schematic I included is how it's supposed to be setup. \$\endgroup\$ – Ageis Dec 10 '11 at 9:42
  • \$\begingroup\$ Can you factory reset it? Most devices allow you to do this with some method. I've had routers that factory reset if you held down the reset button for 5/10 seconds at power up... or... \$\endgroup\$ – kenny Dec 10 '11 at 11:38
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    \$\begingroup\$ @kenny - Factory reset only works if you didn't mess up the firmware image in the EEPROM/wherever it's stored in your router. I actually have an old router somewhere with a bungled firmware flash update, that I never bothered to unbrick. \$\endgroup\$ – Connor Wolf Dec 10 '11 at 12:14

I base my answer on this datasheet. Update: included the information from Fake Names comments Short answer: Your schematic will work, if you connect Vcc to 3.3V, as VccIO will define the levels you drive. If you are a bit concerned about your supply voltage of 3.68V, you could also connect this voltage to Vcc only, and feed the 3V3OUT pin into VccIO:

To ensure the stable operation of the internal oscillator of the FT232 you want to use a supply voltage of >4.0V (see page 9 of datasheet, note 1). This is not a problem since USB provides 5V. The voltage of the logic output is determined via the VCCIO pin, in your case you want to provide 3.3V there. The chip has an pin 3V3OUT, which can be used for this:

page 8 of datasheet

Your circuit will then look like this:

enter image description here (with Vcc = 5V from USB)

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    \$\begingroup\$ It's worth noting that if you are using the FT232's internal oscillator (and you are), you are supposed to have a supply voltage > 4.0V. For values of VCC between 3.3-3.9, you need a external clock source. However, for what it's worth, I have accidentally run a FT232 on it's internal clock with a 3.3V VCC with no problems. It's out of spec, but it seems to work anyways. \$\endgroup\$ – Connor Wolf Dec 10 '11 at 12:11
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    \$\begingroup\$ In this case, it would probably be easier to strap VCCIO to 3V3OUT, and run the chip of 5V form the USB connection. \$\endgroup\$ – Connor Wolf Dec 10 '11 at 12:12
  • \$\begingroup\$ Specifically, The VCC Pin Specs are: +3.3V to +5.25V supply to the device core. (see Note 1) . "Note 1" is: The minimum operating voltage VCC must be +4.0V (could use VBUS=+5V) when using the internal clock generator. Operation at +3.3V is possible using an external crystal oscillator. \$\endgroup\$ – Connor Wolf Dec 10 '11 at 13:48
  • \$\begingroup\$ Really, it's pretty horrible that FTDI put such a vital implementation detail in a footnote, on a completely different page. \$\endgroup\$ – Connor Wolf Dec 10 '11 at 13:49
  • \$\begingroup\$ get that right bro. Anyways I couldn't get it working on my breadboard for some reason so I just used my modified my arduino to use 3.3v for the uart interface but 5v for the core. \$\endgroup\$ – Ageis Dec 11 '11 at 21:28

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