Axe210 problem

R

rarcher2

New Member
Hi all.

I need some help with the Axe210 board please?

I bought the Xbee starter kit (2x Axe210 boards + Xbee modules, 1 x Picaxe 18X and 2 x MAX3232 chips).

All worked fine during testing and setup as in the Picaxe and XBee tutorial with Board A (Max 3232) and Board B (Picaxe)

Today I powered up Board A and it worked fine, I can communicate with it via the serial cable and the XBee status LED's are flashing.

I powered up Board B but there's no XBee LED's flashing. I connected the serial cable to Board B and I downloaded a program to the Picaxe, but there's no communication with the XBee.

I swapped chips between boards and all chips work fine on Board A, but neither XBee works on Board B.

I removed all chips from Board B and checked the voltages on the XBee pins and got 3.5 volts on both the 3V pin and the GND pin. On Board A I get 3V and 0.3mV respectively.

So what could be wrong with Board B? Have I fried the voltage regulators? They're the later MCP1702 chips. I'm using the 4.5 volt battery packs supplied with the kit.

Any help would be appreciated.

Thanks
rarcher2
 
E

eclectic

Moderator
@Russell

The Sandbox is just for test-posts.

Suggest that you re-post in the Active Forum,
if a Moderator doesn't move the thread.

e
 
hippy

hippy

Technical Support
Staff member
Moved to Active Forum.

rarcher2 said:
I removed all chips from Board B and checked the voltages on the XBee pins and got 3.5 volts on both the 3V pin and the GND pin. On Board A I get 3V and 0.3mV respectively
Click to expand...
That's identified the fault but I'm not sure what the problem is.

When measuring these voltages what are you using as a 0V reference ? The 0V reference would normally also be the Board and XBee 0V/GND so it should be impossible to read 3V - This suggests the XBee 0V/GND pin does not connect directly to board 0V/GND.

Next step is to continuity check the XBee GND pin through the socket onto the Board 0V/GND and other 0V/GND tracks.
 
B

BeanieBots

Moderator
Could be a socket problem.
As suggested by Hippy, check for continuity between supply 0v and socket 0v.
Then check for continuity between supply 0v and the Xbee 0v pin.

If you are getting 3v3 on the Xbee power pin, it sounds like your regulator is OK.
 
Buzby

Buzby

Senior Member
Hi all,

I too am having a problem when moving XBee from AXE210 to my own board, but it's not a ground problem.

The XBee receives when in the AXE210, but not in my board.

I've use a Sparkfun XBee Breakout to go from 2mm to 0.1in pins, so all the following voltages are measured on the top of the XBee module itself, just to be sure all connections are made.

GND is Ov, and is connected all the way from the regulator.

Vcc is 3.29 v all in the right places.

RESET is pulled high with a 4.7k to Vcc.

There are, at the moment, no other connections to the XBee.

I have, very naughtily I know, soldered a LED+820R temporarily directly on the back of the XBee between GND and the Dout line.

When fitted in an AXE210 the LED flickers off with each TX from the other XBee.

When fitted in my board the LED stays on solid.

The XBee documentation says that all unused pins can be left floating, as I have done.

I am completely at a loss as to what it could be.

Any ideas ?.

Cheers,

Buzby
 
hippy

hippy

Technical Support
Staff member
Sounds like there possibly is a connection to the XBee even if not intended, perhaps TX from PICAXE to TX from XBee, or a short on the board ? You haven't simply forgotten to cut any vero-board tracking between the two sets of XBee pins have you ( not that I've ever done anything like that ).

Posting a photo if you have one will give people something to cast their eyes over.
 
Buzby

Buzby

Senior Member
Hi Hippy,

A trackboard problem was my first thought, but I still double checked, and it's OK. ( Also, I use tri-pad board, it means no track cuts to forget !. )

In order to get as basic a circuit as possible, I plugged the XBee into a breadboard, and just connected two AA batts. No other connections remotely possible.

Still no joy. Exactly the same, LED on solid. Only flickers when in AXE210 board. ( I even removed the PICaxe 18 from the AX210, so it has no chips at all. LED still shows RX. )

My next step is to record the voltage on each XBee pin in the two different boards, then see if I can deduce anything from that.

Is there a full circuit diagram of the AX210 board anywhere ?

Cheers,

Buzby.
 
Buzby

Buzby

Senior Member
Hi Hippy,

I've fixed it, well, sort of !.

Using the Rev-Ed XBee Wizard I reset both XBees, now they work in either the AX210 or my board.

I had originally configured the XBees using the X-CTU software. I've double checked, and I did not set-up any handshaking, either hardware or software.

So its mystery, but I will have to solve it, because I need to use X-CTU as I will need to configure the IO pass-through capabilities.

Cheers,

Buzby
 
R

rarcher2

New Member
Hi, Hippy.

Thank you for the response. I did as you suggested and these are the results:

Continuity check (using an ohmmeter):
Board Gnd - XBee socket Gnd = infinity
Board Gnd - XBee output Gnd = infinity
XBee socket Gnd - XBee output Gnd = 0 Ohm

Voltage check with no IC's:
Board Gnd - Board 5V = 4.6V (I'm using a battery pack)
Board Gnd - XBee socket Vcc = 3.3V
Board Gnd - XBee socket Gnd = 3.3V
XBee Socket Gnd - Xbee socket Vcc = -10mV or less

I'm no expert at electronics and a total newbie to Picaxe, but the voltage checks seem a bit odd. What else can I check?

Thanks for your help
rarcher2
 
B

BeanieBots

Moderator
Something VERY wrong there:confused:

Looks like a broken track between board ground and the Xbee socket.
Not 100% sure about your result for Xbee Vcc but -10mV doesn't sound right.

With those results, I'd be looking for an obvious break and/or dry solder joint.
 
R

rarcher2

New Member
Hi, BeanieBots.

Thanks for the quick response, and your reply is somewhat what I'd guessed.

I've checked all the solder joints and they appear to be fine. Is there somewhere a drawing of the board track layout so that I can begin looking for a broken/damaged track or joint?

Thanks
rarcher2
 
D

Dippy

Moderator
To check a dicky track you can 'follow' the track with a sharp MM probe and use a magnifying glass. You may need to penetrate any resist.
I'm afraid physical inspection means you have to get physical.
Is the socket OK?
Errors like this are usually poor (or missed) soldering, wire,link or connector. A broken track is unlikely (not impossible) on a pro-made board.

I've never used that board, I assume there are no magic jumpers,switches or links?
 
Buzby

Buzby

Senior Member
Hi rarcher2,

Don't trust the 2mm connectors !.

Depending on which manufacturer supplied them, they can be very dodgy when hand soldered. I've seen mention on another website about people having issues with poor connections.

With the XBee fitted, but no power applied, try the following.

Check continuity from GND ( near the bottom left reset switch ) to the solder on the top of the XBee module, directly above the H1/GND pin. This should be zero ohms, if it's not then it's highly likely the 2mm socket is not making proper contact.

There should also be zero ohms between all of the following points on the board.
GND pad, top left near download socket.
GND pad, bottom left near reset switch.
GND pad, right hand edge.
The two small circles ( through-hole pads ) near the 'X' and 'r' of the words 'XBee Pro', above the right hand reset switch.

If there is not zero ohms between any of the above then there is a PCB fault.

There should also be zero ohms between the 3.3v locations.
3v pad, top right corner.
Solder joint at Pin 1 on top of XBee module.

As Dippy says, it's not impossible for a PCB top have a dodgy track, but it is very, very, rare.

Far more likely is the 2mm socket.

Cheers,

Buzby.
 
R

rarcher2

New Member
Hi, Buzby, BeanieBots & Dippy.

I followed your suggestions and checked voltages and continuity, and found I'd managed to break a track between the Picaxe Reset button and the Picaxe GND out. I put a jumper wire in and all seems to be working. I need to do a complete ping test etc but lights are blinking and comms seems to be working.

Thank you for all your help and your quick replies.

Cheers
rarcher2
 
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