How is this function returning xbee.getResponse().isAvailable() = false, even before the timeout has expired?

XBee & XBee Gateway XBee Programamble (S2C & 900 HP)
1

I’m using a pair of Xbee S1 802.15.4. I modeled this function after the library Rx example. It’s supposed to classify the types of frames that are coming in. Thing is, I’ll frequently get a frame that triggers the else{} part of the function, indicating that no frame is available. But I know that the frame was somehow received because the timeout hasn’t expired yet! And when I plug the receiver into XCTU, The frames arrive looking just fine.

There must be something I’m doing wrong here with my syntax.Can anyone spot my mistake? I couldn’t find any good way to post code here, so I made a duplicate post on a different forum and linked it here: https://www.reddit.com/r/xbee/comments/4zqyjj/how_is_this_function_returning/

2

What are the API frames you are receiving? Can you provide the full frame?

3

Thanks for asking, my transmitting Xbee is in AT mode, and my payload is 13 characters long, counting the terminating zero (or 14, if you count the line return) . It arrives at the receiving end as frame type 81 (RX (RECEIVE) PACKET 16-BIT ADDRESS).

I can’t share the payload with you, but it’s just a string of 14 ascii numbers and characters. I’ll replace them here with XX’s:

RX (Receive) Packet 16-bit Address (API 2)

7E 00 7D 33 81 00 33 30 00 60 30 24 20 32 2E 33 30 31 32 37 2A 0D 0A A9

Start delimiter: 7E
Length: 00 13 (19)
Frame type: 81 (RX (Receive) Packet 16-bit Address)
16-bit source address: 00 33
RSSI: 30
Options: 00
RF data: XX XX XX XX XX XX XX XX XX XX XX XX XX XX
Checksum: A9

I’d also like to add that I’m having a strange problem with “invalid frames”, which occurs when I either close and reopen my serial terminal in XCTU, or if I take the receiver out of range and back in again. I don’t think this is related, but I thought I’d mention it. I’ll probably make a post for it.

4

Sounds like you have other issues that may be connected. How are you connecting this 3V XBee to your device? What voltage does that device operate at?

5

I’m using the Seeedstudio Xbee shield V2.2, which provides 3.3V.

http://wiki.seeedstudio.com/wiki/XBee_Shield_V2.0

I made a separate post here on this forum describing the problem.

http://www.digi.com/support/forum/58181/invalid-frames-problem?show=58190#a58190