I just was playing around a little running the Carambola SoC stand alone (without dev-board). The picture blow shows what needs to be connected to boot the Carambola, access it through serial line (by using a TTL USB to serial converter), and optionally connect USB (I used a web cam):
Carambola Stand Alone (with USB)
Some notes about power consumption:
- You need to supply at least 300mA, otherwise the Carambola is starving.
Some notes about the USB connection:
- For using USB, 5V has to be provided to pin 21 (when not using USB, there is no need to provide 5V).
- UPHY (pin 40) needs to be grounded to tell the USB controller to run in master mode.
- No ESD protection when connecting as described! Thus, I recommend not to hot-plug devices when using this unprotected approach!
Hi Stefan,
thanks for sharing this, i want to try this out.
But what converter i need?
I found a cable and adapter
http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm
http://nodna.de/Droids-USB-zu-Serial-Adapter
Which is the right on to get it started or which on have you used?
Best wishes
Rudi
Hi Rudi,
in general, all adapters using 3.3v TTL signal level should do the trick. As long as you do not intend to power the Carambola from the power output provided by the cable, the TTL-232RG-VSW3V3-WE would work great. If you intend to power the Carambola from the Cable, you could try the TTL-232RG-VREG3V3-WE (which offers 3.3V@250mA). But in general I would not recommand supplying the Carambola from the serial adapter since, depending on what you do with the Carambola, it may draw slightly more then 250mA … The one from NoDNA should also work but it is pretty expensive. I for example successfully use this (Prolific Based) cheap one:
http://www.watterott.com/de/Adafruit-USB-to-TTL-Serial-Cable?xcbf51=7ca18179cf0a30fd8ad2ebad40fabb42
which is from adafruit:
http://www.adafruit.com/products/954
Thanks for suggestion.
I don not deal with this yet. But WLAN/USB-options and the mpeg-streamer need to adjust before starting, i think.
Are the installations run above the serial?
I also want to stream a webcam with the carambola. Whats the better way to supply the board?
Hi Rudi,
by installing you mean putting a new firmware on the Carambola? Actually flashing a firmware works like this: you advice the bootloader to flash a new firmware image by dowloading it from a TFTP server (which you usually run on your desktop) and flash it to internal NAND. Advising the bootloader is done through a connection over the serial line. Thus, one would need two (hardware) things for flashing: a serial connection (through the converter we talked about earlier), and a LAN connection on eth0 (bootloader does not support WiFi). Thus, I would totally sugest using the [Carambola dev-board] for delvelopment since it provides the ethernet connectors as well as an integrated serial converter. As soon as you have a running Linux on the board, you also could flash it from that Linux (and you also could use WiFi then). In general, the steps needed to build a new firmware and upload it are descibed very well in the [Carambola Wiki].
For the powering of the Carambola: I power one of my [Carambolas through a 7.4V LiPo battery]. Since I am also connecting a USB WebCam to it, I need to supply both: 3.3V and 5V. To do so, I use two [step-down converts from Pololu]. But they are expensive
, but the regulators commenly used in that cases are all SMD, and unless you build your own PCB around the SoC, this is the easiest way … Again: you could also use the Carambola on the dev-board, and power it directely from a battery since it already provides step-downs (well and buying two of the Pololu step-downs is almoust the price of the dev-board).
Regards,
Stefan
Thanks Stefan. I think I got all information to get the board started.
I orderd the set(carambola, dev-board) and only need a Lipo and the Pololu step-down converter. But one last question still I have.
Normally my cam is running at a 3.7V Lipo and load at USB. Today I checked, that it could be running without the battery at 3.3V
To economize one of the expensive Pololu, I want to run the cam directly through converter (like the carambola).
Is it possible to run the USB without 5V power(only datalines)?
I think so, but need certainty, because I am absolutly loan. Try and error is no oppertunity. Wont crash something.
Thank you again for aid!!!
Hi Rudi,
to my knowledge it is not possible to run USB without additional 5V power supply to the carambola.
Regards,
Stefan
Sorry, but one thing I forgot to ask. I googled but nothing found about that. Did you know the max input current? Because the max of the Pololu is 600mA and i dont know yet how much the cam have. I need to measure it next days.
Depends on the cam you use. I don’t expect a cam to draw 600mA. I use a cheap Logitech HD USB cam which even does not draw 100mA … If I remember correctly, my whole setup (using two Pololu step-downs) including a USB webcam was about to draw 250mA at 7V (which is about 1.75W).