Need a wireless serial cable solution.

T&E Engineer

Is there any product to wirelessly replace a serial cable that is going from a PC com port to an Sx chip project? I know that Parallax makes the receivers and transmitters which is ok for the sx end but on the transmitting end I would like something more in a completed box or module with a db9 connector that I can connect the PC to. Ideas or comments?

Lord Steve

What baud rate?

Bean

The bluetooth module from Parallax should work for the SX side.

http://www.parallax.com/Store/Education/CustomKits/tabid/134/txtSearch/bluetooth/List/1/ProductID/41/Default.aspx?SortField=ProductName%2cProductName

Any bluetooth adapter should work on the PC side. These can be purhased at most consumer electronic stores (even wal-mart).

Bean.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
"A government big enough to give you everything you want, is big enough to take away everything you·have."·· Thomas Jefferson

"It is our choices, Harry, that show what we truly are, far more than our abilities."·Dumbledore from Harry Potter

www.iElectronicDesigns.com

·

T&E Engineer

I currently receive Hyperterminal data at the SX side at 38400 but I'm sure any slower speed would be fine as there is only 64 bytes being received.

This is for my Display sign/clock. I currently have it in my living room and if I loose power (rarely) to the clock (DS1302 based), it needs to be reprogrammed by a laptop via Hypeterminal with the correct time and date (text file). This means I need to bring my laptop out to the living room for this which is probably still the cheapest cost effective method. Since my desktop and laptop is in the bedroom (<30 feet), I was thinking of doing it wirelessly. That's all.

Thanks for the good idea.

bennettdan

Try these out and just use a usb bluetooth adaptor from say walmart on the PC end....

https://www.aircable.net/catalog/product_info.php?cPath=28&products_id=37&osCsid=l32kordp82j6cakapocdq09b47

T&amp;E Engineer

Thanks for all the great feedback on this. I'm still debating on the cost effectiveness of doing this manually by just bringing my laptop over when power is lost (rarely) - or spending a significant amount to somewhat automate this.

Thanks for the good input!

RobotWorkshop

One module that I've had really good results with is by A7 Engineering. Their eb501 module has RS-232, as well as 3.3v and 5v logic level serial interfaces on board. You can pair them up to directly replace many serial cables or you can link it up to an existing Bluetooth adapter on a PC or laptop. I just have a ZOOM USB Bluetooth adapter on my PC which works great. I've just got the regular antenna on the module and the range has been excellent. You can see them at:

http://www.a7eng.com/products/bluetooth/productpages/eb501-ser.htm

If you have this wireless connection available and your computer is online you could try setting up a scheduled task to push out the current time on a regular basis. Referencing an NTP server to keep your PC's time in sync will help ensure that you always see the right time on your display.

It might take a little work to setup at first but after that it you shouldn't have to worry about it.

Robert

T&amp;E Engineer

I like what you are saying RobotWorkshop. It looks like a couple of these devices (although would not be the cheapest method) - would make a unique way to control issues such as power loss to the clock. I like how it has the DB9 already on them. Although I would need to purchase antenna's and power supplies (maybe at least 1 for the PC side).

All good ideas guys!

RDL2004

I'm just curious, was there some difficulty which prevented the addition of battery back up for the DS1302? This would seem to be the most simple solution to the problem.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Rick

RobotWorkshop

If your PC has a USB port then you don't need to buy two of them. You'd only need a pair if you need to use a regular serial port on your PC. Just get a regular USB Bluetooth adapter for the PC. The one I bought was made by ZOOM (Model 4310) and had a little antenna on it. Make sure you get the class 1 versions since they are rated at 100m (330ft). Once the eb501 is paired up with the Bluetooth adatper on the PC it will appear as just another COM port even though you aren't using a physical COM port on your PC.

On the eb501 module at your display panel all you need to buy if the module and antenna. Just wire it up the 5v logic level serial to your SX processor and just tap off existing power from your display if it is available. That way you won't even need an extra power cube.

This is exactly what I used on one of my robots and it works out great! It was in the May, 2008 issue of SERVO magazine. Since I originally bought two of these modules the second one is going on another robot....

Robert

T&amp;E Engineer

I tried adding a 3 volt watch cell to it on pin 8 and ground and it did not keep the time - but that's right I guess I could experiment more on that end.

Does anyone know if there is any sort of additional programming that needs to take place to use a battery backup? I saw something once on trickle charging or something that made me think of this. Perhaps it is in my DS1302 coding, is why simply adding a watch battery to pin 8 did not get it to work too.

RDL2004

The functioning of the back up battery should be automatic when Vcc2 drops below Vcc1. You do not need any code. I think trickle charging is an unnecessary complication in this case. If you have any code pertaining to the trickle charging, I would try again with that code removed. Be sure to use a fresh battery and observe correct polarity. Make certain the + side of the battery is connected only to Vcc1 so that it is not accidentally drained by other circuitry.




▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Rick