Shop OBEX P1 Docs P2 Docs Learn Events
XBEE to 4D uLCD display — Parallax Forums

XBEE to 4D uLCD display

EMHmark7EMHmark7 Posts: 93
edited 2014-05-16 08:17 in Accessories
Hi,

I keep this post so it can help in your future adventures if you end up being blind of a trap you may have created yourself. (solution billow)

Besides posting on 4D forum (big time zone gap),
I am coming back to most responsive forum I know of.

I am using the XBEE on the uLCD43-PT that is my remote control.
I can send a char and a device (Propeller with XBEE) is receiving it and replying a char.
But still, at the remote, as response, I get -1 (no char available on the uLCD serial).


SOLUTION:

For testing purposes, I previously set a kind of interpreter listening to the QuickStart USB serial Terminal for instructions as if it were coming from the wireless remote control (the uLCD display)
Once an operation is done, Propeller sends an Acknowledgement to that port.

But once in real operations, we need to make sure the interpreter receiving instructions from wireless is sending not only (optional) ACK to the serial USB monitor if connected, but primarily to the wireless remote too, otherwise it will not receive anything of course (the ACK it was expecting).
Normally, it means 2 instructions using 2 different serial ports.

At first sight, the instruction may look the same because doing one single job: (sending a value), but the prefix selecting the port is important.

In my case here are the 2 instructions:

XB.tx("q") 'ACK the most important: to the remote control
PC.Char("q") 'for monitoring to PC

Also, from my experience, if you test a pin on the XBEE, a LED will light long enough but tricky for a good contact on your flying wire.
The XBEE pin is small (out of the PCB) and if there is no light at all it is maybe simply a bad probe contact.
Also, for getting the light tight, using an external 3V and the LED with a pull up resistor, I had to link the two grounds.
In XBEE case and my method, it is the logical 0 that lights the LED.

Thanks,
Marc
Sign In or Register to comment.