Serial LIght Adapter

New to Arduino. Sorry if this is really stoooopid. I want to connect a keyboard to an Arduino Uno
via a USB-serial light adapter (USBSLA). Sketch should be pretty simple, but it simply ain’t working.
The TX/RX lights on the serial adaptor don’t do anything at all. I’m not trying to use it to
connect to a Mini (which is what a lot of posts focus on).
Am I missing something really really really obvious?

Sorry if I should have posted elsewhere, looked at some website I missed, offended someone’s sense of what this forum should be about, etc. Just really need some help or pointers (including
troubleshooting steps).

xxxx
5V on USBSLA – 5V on UNO
GND/BLK on USBSLA – GND on UNO
TX on USBSLA – 6 on UNO
RX on USBSLA – 7 on UNO.
xxxx
#include <SoftwareSerial.h>
SoftwareSerial USB(6,7);

void setup() {
Serial.begin(9600);
USB.begin(9600);
delay(2000);
Serial.println(“starting”);
}

void loop() {
if (USB.available()) {
Serial.println(USB.read());
}
}

Normally keyboards are USB slaves, as is the USB/Serial adapter. An Uno needs a USB Host shield, ex. https://www.sparkfun.com/products/9947 so it can act as a USB Host & control a slave device.

I'm trying to prototype something in several steps; the USB Host is too big; the Serial Light Adapter seemed like a natural next step.

Nope, only offers a USB slave connection for non-USB/Serial adapter chip equipped boards (promini, etc. ) Many of my designs use it off offboard PC connection when on-board is not needed for an embedded application.

Boards with 32U4 chips can be programmed to be HID controllers. (Leonardo) Boards with 16U2 chips can re-program that chip to be an HID controllers. (Uno).