Hello to everyone!
I have to connect a badge reader, that is working as a keyboard emulator, to Arduino UNO R4 Wifi shield.
Alternatively to use the USB shield, could be correct to use an USB to TTL converter and connect then the reader to the converter and the converter to serial ports (0 and 1) of the shield?
Do you think it's correct and it can be feasible?
Let me know your idea and if you think there could be a better way to do it.
Thanks!
Have a nice day!
T.
The Arduino USB Host Shield is not a board we produce anymore, we have discontinued it a while back (https://docs.arduino.cc/retired/shields/arduino-usb-host-shield).
Some 3rd parties may produce clones, but I'm not aware of current firmware efforts by said parties to maintain the product.
This is why we do not officially support that shield.
You can find a list of UNO R4 compatible shields here
Additionally, a USB HID (Human Interface Device) such as a badge reader will not produce USB Serial signals which can be simply translated using a USB to TTL converter.
They require a host to talk over USB HID protocols and exchange data.
These devices tend to work as keyboards and produce key sequences to be used by the host.
I don't think you'll be able to easily do this without an additional piece of hardware between the scanner and the UNO R4.
You need something that can detect a USB keyboard.
Hope the information above is informative enough to help you direct your efforts 
You may also want to take a look at this thread
Thank you for your reply.
So, usb to ttl converter is not enough…
At this point, it might be better to use directly a reader of rfid?
I found this one that works with the frequency of our badges:
[
DollaTek RDM6300 Modulo Lettore RFID 125Khz EM4100 Modulo Controllo accessi Uscita UART per Arduino
amzn.eu
UART exit, so can I connect it to pins 0 and 1 of R4 Wi-Fi? And the directly read from Serial?
if you need to use an RFID reader make sure it is compatible with your tags.
The one I have personally tested is the MFRC522 which works using SPI.
It also contains examples.
Not all RFID/NFC tags are the same, and some cannot be read without specific hardware.
First research what the protocol and security features of your tags are
u.
Thanks a lot: I think this is the right reader since the frequency, 125 kHz, is the one of the tags, same for standard, EM 4100
T.
Thanks for your suggestion: I already dealt with that, but now I know frequency and standard.
Probably I’ll try to use directly an RFID coil and pcb with an UART output, so I can bypass the conversion from USB reader.
