Help required Arudino board

[Amruth]

Hi
What kind of Arundino platform is required for ATA development. I am
planning to use
http://www.arduino.cc/en/Main/ArduinoBoardDuemilanove

Please let me know.
Thanks

[David Rowe]

Hello Amruth,

I think the Duemilanove would be OK. One issue we need to work around
is access to the RS232 port on the Arduino, this is usually dedicated to
the USB port that talks to the host PC. Some research may be required
to work out the best way to do this, and still retain the ability to
download programs via the Host PC.

For initial testing of the AVR software we could use the Host PC to
send/receive samples via /dev/ttyUSB0 I guess.

Cheers,

David

--
Free Telephony Project
open embedded IP-PBX hardware and software
http://www.rowetel.com/ucasterisk

[amruth pattanada]

Hi

David

I believe Duemilanove does not have RS232 port. It has USB port. We can download programs using bulk out endpoint which I have done already for TI3410 chipset. The device appears as serial device /dev/ttyUSB0 to host and we can use serial port to program Arudino board. I am yet to get hold of Arudino board.

Thanks

Amruth p.v

[David Rowe]

Hi Amruth,

The USB chip connects to the atmega8 serial port, and the serial port rx
and tx pins are broken out to pins 0 and 1 of J1, e.g. in the top right
hand side of the photo on this page:

http://arduino.cc/en/Main/ArduinoBoardDuemilanove

Check out the schematic:

http://arduino.cc/en/uploads/Main/arduino-duemilanove-schematic.pdf

Due to R8 and R9 we may be able to "override" the serial signal from the
USB chip when using the atmega RS232 UART in our application. I think
there are some notes on this somewhere, but haven't tracked them down
yet.

There are also some older Arduino boards with RS232 ports rather than
USB. As an alternative it is of course possible to simply plug an
atmega AVR chip into a breadboard, add a few parts like the Xtal and
program via a LPT port and avrdude.

Cheers,

David

[David Rowe]

Over the past few months I have been working under contract from the
Shuttleworth Foundation on the Mesh Potato project:

http://www.rowetel.com/blog/?p=70

The Mesh Potato absorbed quite a few of the ideas I had for the $10 ATA.
Lately I have been working on sending and receiving audio samples
through an OpenWRT router RS232 console port, and interfacing to
Asterisk. Previously we tested echo cancellation and the Speex, which
ran well on an Atheros based router (Ubiquity Nanostation).

This same router firmware would work quite nicely with the $10 ATA -
which means a big boost for the $10 ATA project.

What we need now is for some microcontroller code to be written to
interface the RS232 samples to the A/D and D/A of the microcontroller.
Much of this has been prototyped (see previous posts). I don't have
time for this myself but would be very happy to support anyone who wants
to work on this.

Cheers,

David

[amruth pattanada]

Hi

David
Please suggest me an ideal Arudino board for this project. I will try get it.

Thanks

Amruth p.v

[David Rowe]

Hello Amruth,

I don't think the type of Arduino board is critical - I have a
Duemilanove.

- David

[amruth pattanada]

Hi David

OK. Can I build one for myself. Is it that simple to build using breadboard. I can build it but require ISP for programming it. Earlier I have done PLD programming but for AVR I am not sure what type ISP is required.

[amruth pattanada]

 

In your previous email, you have indicated

"Due to R8 and R9 we may be able to "override" the serial signal from the
USB chip when using the atmega RS232 UART in our application.  "

 

Is it TTL level signals. Can I plug in RS232 port directly to PC.  Don't we require MAX-232 chip.

[David Rowe]

> In your previous email, you have indicated
> "Due to R8 and R9 we may be able to "override" the serial signal from
> the
> USB chip when using the atmega RS232 UART in our application. "
>
> Is it TTL level signals. Can I plug in RS232 port directly to PC.
> Don't we require MAX-232 chip.

For testing with a PC, just use the USB-serial converter already on the
Arduino, so read/write RS232 bytes from something like /dev/ttyUSB0
(assuming it's a Linux x86 PC).

We would need the Arduino RS232 TTL level tx/rx signals when connecting
to the router.

Cheers,

David

[amruth pattanada]

Hi

My router does not have RS232 port. It has only ethernet and telephone interface. It is linksys router and does not support openwrt.

Is it drawback for the work or there is any workaround.

[David Rowe]

Running OpenWRT is a major drawback. Most routers have an internal
RS232 connection that can be broken our using a MAX232 and a little
soldering.

[amruth pattanada]

Can I use existing router that is what you mean and look for RS232 connection internally, pull out RX and TX signals from it. I  already have MAX232 convertor.Arudino RX and TX at R8 and R9 can be directly connected to RX and TX of the internal RS232 router with with MAX232 convertor.

[David Rowe]

On Thu, 2009-02-26 at 23:43 -0800, amruth pattanada wrote:
> Can I use existing router that is what you mean and look for RS232
> connection internally, pull out RX and TX signals from it. I already
> have MAX232 convertor.Arudino RX and TX at R8 and R9 can be directly
> connected to RX and TX of the internal RS232 router with with MAX232
> convertor.

Yes I think you can connect a router RS232 TX/RX to Arduino RS232 TX/RX,
but a level converter is generally not required as the router RS232
signals are almost always 3V3 levels.

[David Rowe]

Hello,

The Mesh Potato project absorbed many of the ideas of the $10 ATA and
has been progressing well lately. The Mesh Potato is a custom Wifi
router with a microcontroller and FXS port. Many blog posts here:

http://www.villagetelco.org

This means that much of the host-side software required for $10 ATA
concept has been developed, for example sample I/O over the RS232 UART,
an Asterisk channel driver, DTMF detection and echo cancellation, all
running on a version of OpwnWRT. This software could run on many Wifi
routers.

The major difference is that the Mesh Potato uses an off the shelf FXS
module that are expensive quantity. What we need for the $10 ATA
concept is some continued development of a low cost FXS interface based
around a microcontroller.

There are many synergies between the $10 ATA and the Mesh Potato
project. If we can develop a low cost FXS interface we could build a
$10 board that could make any Wifi router into a Mesh Potato. The Mesh
Potato could use the low cost FXS interface to reduce it's manufacture
cost.

Also of interest - some kind people have submitted some low cost FXS
circuits:

http://www.rowetel.com/ucasterisk/hardware.html#slic

Cheers,

David