Radio Link

[tichy]

Hello,
I have hooked up the ServoPod with a Radio Link (Easy Radio ER900TRS) but it doesn't work without a hardware handshake. The modules need some time to process the serial data, even at 2400 bps. So if you send 23000 111 + . CR via the link you get back 23 BL, the rest is lost. Any solution to this?

[nmitech]

Have you try to tie the Host Ready Input line low on both host & remote modules?

[tichy]

Yes, it is really a timing issue.
I implemented a link with SCI1 by putting in adequate pauses and tried then to do a software/hardware handshake with PA1 using the busy signal of the easy radio transceiver shio, this works also.
I suggest for future ServoPod to implement a optional full hardware handshake with appropriate signal level converters for rs232 standard.

[RMDumse]

There are some RF modules which are fast enough to keep up with the 'Pod's even at 115200. Specifically, the Sparkfun BlueSMiRFs, and the XBee Maxstreams. We're designing adapters for both now.

[tichy]

I have ordered one of those and their RS232 Adapter, but it doesn't work with the ServoPod. Adapter problem I think.

[RMDumse]

The Blue SMiRF has TTL signals. Those can be run straight into the PlugaPod(TM) easily. Either IsoPod(TM) or ServoPod(TM) can be configured to have their second serial port as TTL when built at the factory.

However, even with both serials set for RS-232, using the Blue SMiRF and an RS-232 adapter should work.

What about the adapter wasn't working for you? Which port were you trying?

[joserojo]

Hey RMDumse, thanks for the info about the wireless modules, I was wondering if you had a chance to look at the modules made by www.radiotronix.com I am actually using the WI.232DTS for wireless comunications with my Servopod installed in a Lynxmotion Hepapod III, and the module is great!!... up to 115Kbps ( I haven't tried it to that speed yet) it has embedded CRC and point-point or master-slave configurations over a long distance and each module is fairly cheap at $26.39 (www.mouser.com)

just my 2 cents.... :-)

[RMDumse]

No, I wasn't aware of the new Radiotronix modules. I will look at them more indepth.

LC has made a MaxStream XBee to PlugaPod(TM) adapter module, so we may soon have ZigBee (XBee) capabilities. Some of those modules are as cheap as $20.

[tichy]

@ RMDumse What about the adapter wasn't working for you? Which port were you trying?
I was trying the adapter delivered with the BlueSMiRF board (which is really a "il cheapo" solution) on Servodpod serial 1. I will try now a standard MAX232 IC and report again.
BTW I would suggest a modification to the ServodPod: provide jumpers to switch both serial port from TTL to RS232. Hardware handshake would be nice in order to cope with any RF solution.