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trouble with mini breakout board and xbee

idata
Community Manager
2,205 Views

i'm trying to take some sensor data via xbee to a mini breakout board and there to a server, i'm using a level converter (https://www.sparkfun.com/products/12009 SparkFun Logic Level Converter - Bi-Directional - BOB-12009 - SparkFun Electronics) to connect the edison with the xbee but using the oscilloscope i found the edison can't make the signal go low when all is connected.

someone have had a similar problem and have a solution to it

1 Solution
idata
Community Manager
382 Views

well after reading the schematic of the shield (https://www.arduino.cc/en/uploads/Main/arduino_WirelessShield_Proto_v3-schematic.pdf https://www.arduino.cc/en/uploads/Main/arduino_WirelessShield_Proto_v3-schematic.pdf) i finally desist to connect direct to the xbee through the JP3 and JP4 pins, instead i use the same pins that use the arduino D0(RX) and D1(TX) and connect the 3.3V and the 5V to the shield and works perfect.

thanks a lot Mike-SYR

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36 Replies
MGilm
New Contributor I
187 Views

OK, so there's a "hard" 3V on that line - this is good (looks like we've found the problem).

Clearly you need to verify the wiring/design of the level shifter circuitry. Can you perhaps put the schematic aside, then reverse engineer the level shifter board (assuming nothing) into a wiring diagram, then compare that wiring diagram with the original (desired) schematic? The reverse engineering of the level shifter circuitry might best be done by another person (assuming you have access).

idata
Community Manager
187 Views

I don't get why i have to reverse engeener the level shifter, i know it works fine, also know the xbee works fine but don't work when connected together

MGilm
New Contributor I
187 Views

What I meant by "reverse engineer" was to draw the schematic of the board-to-board wiring without looking at the original schematic you used. Double checking all the labels on the boards etc (again without referring to your hook-up schematic). Then compare the reverse engineered dwg to the original schematic you used to wire it up originally.

1. Shot in the dark - swap RX and TX in one place (basically my original suggestion).

2. Also, does the level shifter not have 4 channels, of which you are using only 2? Can you move your wiring around?

idata
Community Manager
187 Views

sorry i'm no using an "original schematic" i did all the connection based on the datasheets, swap RX and TX is not and a idea as a i said in my reply # 14 i was able to read the info in the edison from the xbee, about moving to the other channels i have done it same result

MGilm
New Contributor I
187 Views

I meant the block diagram-level schematic you supplied earlier. That's your original schematic.

I don't understand your reply totally - did you try the swapping of RX/TX? (I know you don't believe this to be the problem but I'd appreciate the effort)

Of course the xbee board could have a problem. Do you have the capability of isolating that (say doing a loopback on its RXD TXD, or swapping it with another)?

idata
Community Manager
187 Views

To clarify i have 2 xbee, both work because i have tested them with arduino to send data between them, offcourse i hve swaped them with the same result

Now i want to communicate an arduino one with the edison and there is where the problem is, the edison can read the data send by the other but can not write that's why i know that swap RX/TX is not going to help

About the block diagram that i post before was done based un the actual wiring, if that isn't what you wanted to say then please explain me more detailed

Thanks

MGilm
New Contributor I
187 Views

Hi mauro30

I'd like to understand what you tested as mentioned in your Dec 18 post.

You tried 2 different xbee boards, with one Arduino, and had no problem. Correct?

Does the Arduino need a level shifter to talk to the xbee?

idata
Community Manager
187 Views

hi Mike-SYR

Actually i have 2 arduinos so i can test that i can read with one what i send with the other, and both can read and write fine.

as far i read the shields have a level shifter built in the TX arduino(5 V)-RX Xbee (3.3V)

MGilm
New Contributor I
187 Views

Power supply/ground concerns:

In your diagram of Dec 11...

  • From where does the 3.3V (on the right side of the level shifter) come?
  • Where is its return (ground) wired?
  • Is it literally the input (main) voltage to the xbee? Or does the xbee run on a different supply?
  • Is there a DC voltage difference between the ground on the left side of the level shifter and the ground on its right side?

Also, can you disconnect the level shifter TX/RX data lines from the Edison and strap the TX to RX and get the Arduino to hear itself?

And vice versa, can you instead disconnect the level shifter TX/RX from the Arduino and strap them and get the Edison to hear itself?

idata
Community Manager
187 Views

From where does the 3.3V (on the right side of the level shifter) come?

i have tried from a externar power suply and from the 3.3V pin from the arduino

Where is its return (ground) wired?

sorry if i don't get this, the low level ground is returned to pin J19-3 (GND) on the edison, on the high level is returned to the power supply or the GND pin on the arduino

Is it literally the input (main) voltage to the xbee? Or does the xbee run on a different supply?

it's literally the input voltage, the xbee have no other connection to it

Is there a DC voltage difference between the ground on the left side of the level shifter and the ground on its right side?

no, both sides grounds are physical connected in the level shifter

about the echos in the edison and the arduino i can work on it now but for tomorrow i can do it

MGilm
New Contributor I
187 Views

I wanted to be sure that the voltages running the level shifter are gotten from the actual voltages on the respective sides. Sounds like you are doing this.

Also, the grounds seem to be connected to one another. OK.

I'm not sure where else to take this. There seems to be an issue on the Arduino side of the level shifter (the level shifter itself, or the Arduino, or the combination) so I suppose you should focus on finding ways of testing that.

edit: I meant "xbee" above and not "Arduino"

idata
Community Manager
187 Views

i did the echos, the edison hears it self without a trouble but the xbee haves problems, the image below is the pin3 (the xbee RX) the signal is damaged after the level shifter, so this gives ligth that the trouble is between the xbee and the level shifter

idata
Community Manager
187 Views

hi Mike-SYR and Intel_Peter some new thoughts about this problem?

idata
Community Manager
383 Views

well after reading the schematic of the shield (https://www.arduino.cc/en/uploads/Main/arduino_WirelessShield_Proto_v3-schematic.pdf https://www.arduino.cc/en/uploads/Main/arduino_WirelessShield_Proto_v3-schematic.pdf) i finally desist to connect direct to the xbee through the JP3 and JP4 pins, instead i use the same pins that use the arduino D0(RX) and D1(TX) and connect the 3.3V and the 5V to the shield and works perfect.

thanks a lot Mike-SYR

View solution in original post

MGilm
New Contributor I
187 Views

Can you show us the before (not working) and after (working) schematic?

idata
Community Manager
187 Views

hi Mike-SYR better i have photos.

first is the before (not working), balck is GND, green DIN, yellow DOUT and red 3.3V

the after (working) black is DOUT, yellow DIN, left green is GND, rigth green is 5V and blue is 3.3V

this solution is not what i wanted beacuse the shield is to big and a i like to connect the xbee directly but the footprint is not friendly but until i can make the PCB i can work on it

again thank you for your support

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