I noticed that the rfid reader had a db level of 5 so the tag had to be very close. It looks like the LED is flashing with the TX signal. I am not sure how that will affect the relay. I am so EXCITED!!!
could the low DB setting cause the “high return loss, check antenna” message?
massive progress. Congratulations !
with a low 500dbm you need indeed have the tag nearly on the M7E board.
To your question:
could the low DB setting cause the “high return loss, check antenna” message?
no. Actually it is the opposite.
CRC errors means that the received information was incorrect. Each message has CRC bytes at the end that is calculated on the bytes in that message. The library is checking that and that failed.
This can be because of baudrate, bad wiring, bad power, etc
High return loss, check antenna: As the M7E is sending a signal to read a tag, it checks for the returned modulation on that signal done by the tag. If the M7E detects that returned signal is of a too high level, it assumes the antenna could not “send it”. This can caused by a bad antenna or cable errors, or antenna not able to handle the power. Reducing the 500dBm could make that problem happen less, but as a result even less distance between tag and antenna. This detection could also be wrong and caused by power glitches.
Based on the above I assumed a baudrate and power supply or the board connection to the antenna.
You tried the baudrate… maybe that helped on the CRC. For debug you could try to only change back to 38400 and see that it still works. Only for test, else I would actually leave it for the moment.
I am not sure whether you had reduced the read power ?
But it could also be the board. There have been others that had this problem, M7E Hecto not working with Arduino, M7E High Return Loss
I understood that you tried the Universal reader Assistent (URA) before. Does that still work ? (make sure set the URA switch back…)
Else I still suspect power could be an issue. The M7E (like the previous M6E) are very sensitive to good stable power. Maybe you can measure the 5V on the M7E. If you have another PC or better power supply you can try that. and else make sure to have the M7E power wire on the breadboard as close as possible to the MCU board. The less connections in between… the better.
BTW if you are considering external antenna’s you will need for sure external power supplied to the M7E.
yes. bad CRC message did not occur at 9600, so that is good. I will raise it back to 38400 and see
I did not change the dB level - 5 dB was in the original sketch
yes, at 38400 still had the High return loss
voltage going to ME7 - 4.64V
I would like to try the power and make sure connections are good. I noticed on the post that you sent, the person had some sort of adapter that went over the RX/TX VCC GROUND port to allow for jumper wires. Those may help. are those available on sparkfun? these may clean up the connections.
how could i add an additional power supply? I would assume that the arduino needs to be connected to the computer since it requires a key press
Again a step forward.
The 4.64V is only half the story. The M7E works in bursts and thus you need a good power supply that can provide a strong 5V. Wall warts often do not have enough capacitors to provide that.
You can connect external power to the same VCC as you do now (and of course also the GND of the M7E AND ground of the MCU) You can instead connect external strong power to USB-C on the M7E. BUT do NOT do BOTH (VCC AND USB). You need indeed keep the connection to the MCU, also to power the MCU. If you want you can comment out the ask for pressing the key.
Not sure which adapter you refer to, but as long as the wires are solid connected to the M7E, you are good.
Try the manual switch also for the fun and if you can the URA.
this is the part i was talking about
it looks like something that connects to the M7E on those ports…anyway
I think i might try the USB on the M7E. If i plug the power into the M7E, can i read the voltage on the VCC/Ground? that way i can run through different wall warts to see what i get. if they dont give a good 5V are there power supplies that you would recommend?
odd one. when i disconnect the (+) from the arduino, and leaving the ground connected between the M7E and ardunio, I am getting a few millivolts leakage. enough to turn the LED on on the M7E. If i disconnect the power and ground from the arduino and use a wall wart on the M7E, i get 5.1 V but it wont connect to the arduino. - error Module failed to respond. Please check wiring.
as long as i am getting power from the arduino, it connects fine
if you apply and external power supply the GND of the external needs to be connected to the GND of the M7E AND the GND of the MCU board. You need common GND. As indicated before a wall wart most of the time does not have enough power, while it can have enough voltage.
the leakage could be through the TX and RX wires…
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Ok. I will give that a shot. I will have to give the wall wart a shot since that is all i have at the moment. Would this work for a better power supply
i have a breadboard power supply on order and i will report the results. @paulvha You have been a tremendous help. I cant thnak you enough
ok!!! The power suppply was a big help! no more errors and it says scanning. the LED flashes with the TX signal!! seems like it is working. I did try it with the relay and it clicks with the scan so i will have to rewrite the Pin 9 code to stay on for 10 sec and then reset. I will also have to remove the ‘press a key part’. once it get that moving, i will move forward with the external antenna and the necessary M7E adjustments. Will the external antenna work on the 5V from the M7E or will it have a separate power supply
COOL!.. thanks for sharing the good news.
As it relates the relay, which one did you choose ? Some can cause issues/spikes hence my question
External antenna uses board power 
problem number next. my project got knocked off the desk and now i get no response from the reader. When i connect the reader through USB (yes, i switched it back to USB), the universal reader program can’t find it. Does this mean my reader is fried? Any other way to test?
dropped you a direct message. check top right on the “green D” in your case.