USB device connected directly to Arduino Mega 2560

Using Arduino Programming Questions
1

Hi,

I am new to the Arduino environment and have a few questions.

I noticed that when data is being sent from the computer to the Arduino board, the Rx light is active on the Mega 2560.

  1. Does this apply to devices connected to the Arduino Board as well?
    Meaning, if I connected a device that uses a USB cable, would I crossover the wires or do a straight connection? Would the Data + / Tx line on the usb device be connected to the Rx line on the Arduino or would it be a straight connection? Tx - Tx, instead of Tx - Rx

  2. Can the Arduino Mega 2560 (although it uses TTL) communicate with a USB wired device that's connected to a breadboard or directly to the Arduino board, or does it need a shield to convert the data to TTL?

Thanks in advance.

2

USB does not have RX and TX wires, only Data+ and Data-. You can't connect a USB device directly to an Arduino board. Typically you would use an USB Host Shield which uses the MAX3421E chip to provide the host interface. The chip uses SPI to communicate with the Arduino.

3
  1. Does this apply to devices connected to the Arduino Board as well?

The TX and RX LEDs are controlled by the USB to Serial converter chip, not by the Arduino.

4

johnwasser:
USB does not have RX and TX wires, only Data+ and Data-. You can't connect a USB device directly to an Arduino board. Typically you would use an USB Host Shield which uses the MAX3421E chip to provide the host interface. The chip uses SPI to communicate with the Arduino.

https://www.arduino.cc/en/Main/ArduinoUSBHostShield

The Due contains a built-in USB Host.

Regards,
Ray L.

5

Duly noted. Thanks.