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I use Sparkfun simultaneous RFID Reader product (SEN 14066) plug on Arduino UNO ATMEGA 328.
I use your program sample Example2_READ_EPC.
Sometime I have the ErrorMessage “Module Failed to respond, please check Wiring”, Status 1
I must do power off to solve this problem and I cannot do that in my application.
the reset function does not reset the board.

Why have I this error, I don’t find in your documentation why this error comes!

Thank you for your help

Best Regards

Christian Vadant
HI Christian
I had the same issue multiple times. The Nano is very sensitive to enough power. First of all when powered with USB, do not increase read or write power above 500 and then still this error message will happen.Depending on your PC and USB port ( 1.0, 2.0 or 3.0) it might not provide enough power. For me the solution was to add the connector and connect an extra battery of 3.7V to Nano.
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Hi Paul,
Thank you for your reply but I found may be a info:

I have a chip in REV D.
I come to read in ThingMagic Nano Design Guide, that the last Revision of chip is E may be will solve my problem?

Extract from ThingMagic Nano Design Guide
9/2015 01 Rev D -Ambiguity about whether RX and TX pins are inputs or outputs cleared up.
4/2016 01 Rev E - Content added to reinforce that all GPI lines and the RX input line must be low
when the module boots up and low when the module shuts down

what do you think about that?
I have rev D as well. I don't expect that this is the root cause. I could reproduce the error easily by just setting a higher RX/TX power. I had a connected an oscilloscope on the TX lines and the NANO was just providing constant high frequency output. It was clearly "lost in space". Hence it did not react to a reset command and the only recovery was power off and on again. When I connected a charged lithium-battery the problem disappeared. Living in the Netherlands I had ordered this : ... ry-2000mah. But actually the best way is to have a strong external 5V power supply.
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Hi Paul,
Now I used an external power supply and now application run correctly thank you for your help,
but I have always the same problem after each downloading of new version with arduino IDE.
Do you have an idea why?

HI Christian

Good to hear that helped. The issue loading a new version is not one that happens to me. After loading a new sketch, without power-off, an Uno will reset and try to reconnect with the requested speed. The Nano, as it was not power-off, will be in the speed as requested in the previous sketch. e.g. that could be 9600. If the new sketch has a different speed (say 38400) it will first try that 38400, if that fails it will assume that the Nano was powered off /on. A Nano will always restart in 115200 in that case and the sketch will switch the serial to 115200. send a command to the Nano to set for 38400, and set the serial back to 38400. another aspect is that many of the example sketches put the nano in continuous read. A reconnect will will always try to read the firmware level, but the responds could be that of continuous read. (the mode it was set before). The Setupnano() routine tries handling that. Another aspect to try : nano. enableDebugging() in setup. it will give you debug messages and based on that we might be able to detect what is going wrong.
Hi Christian,

Can you please elaborate a bit on what you meant by this?
CVT wrote: Thu Apr 18, 2019 9:31 am
but I have always the same problem after each downloading of new version with arduino IDE.
Are you still getting the "Module failed to respond" error when uploading new code from the Arduino library or something else? What configuration of the RFID Reader+Arduino are you using when the issue shows up? If you can, please take a few photos of the top and bottom of your RFID Reader as well as a couple of photos of the circuit you have it in when the issue pops up and attach them to your response. That will help us get a better idea of what might be causing the issue here.