Connecting Arduino mega 2560 rx1, tx1 to Raspberry Pi USB

Other Hardware General Electronics
1

Hi,

I need to send some data from Arduino mega to a Raspberry Pi.

The easiest way would be to use a USB cable and cut off one USB Connector and connecting the wires
to arduino mega rx1 and tx1 and the other USB Connector to the Raspberry Pi USB.

I think this should work... but I'm a little bit unsure because when searching the internet I only found
connections between Arduino rx and tx with Raspberry Pi GPIO Serial, using a level shifter.

Arduino rx, tx are 5V and the USB spec. is also 5V so there should be no problem?!?

Best regards
Walter

2

I think this should work...

No it won't. USB and serial are two very different incompatible modes of communication.

3

I have had a Mega2560 attached to my Raspberry Pi USB as a virtual com port for years using a standard USB cable. Not sure why you think you need to cut cables apart... USB is a standard... RS232 is a standard... but they are truly not related or compatible. I suppose if you want to agree that both send data serially, ok. That's where the comparison stops.

What you want to do... maybe... is use one of the OTHER mega serial port pins and use a 5V/3.3V level shifter to connect that to the raspberry pi's compatible TX and RX pins on the 40 pin connector maybe.

4

Thank both of you :wink:

I think I found a solution from www.ftdichip.com

The TTL-232R cables are a family of USB to TTL serial UART converter cables incorporating FTDI‟s
FT232RQ USB to Serial UART interface IC device which handles all the USB signalling and protocols. The
cables provide a fast, simple way to connect devices with a TTL level serial interface to USB.

Best regards
Walter

5

I would have mentioned that of course... but you already have one of those on the mega so why not use it?

6

Hi!

I use the usb connector on the mega for uploading new program code and debugging.

As long as I'm coding and debugging the usb connector stays connected... always!

I hate fiddling with cables and connectors while thinking about code. >:(

So I use rx1 and tx1 (Serial1) for sending data to the raspberry pi.

Best regards
Walter

7

Why not program the Mega on the Raspberry Pi, then there is no need to swap anything over between running an programming.

8

Or use an FTDI Basic (or equivalent clone) on a Mega port (Serial1, Serial2, or Serial3) and use that to have a USB interface to the RPi if that's what you really want.
$6.90 from here www.tinyosshop.com available with mini-B and micro-B connectors. One of them even ships with USB-A to USB-B cable.
You can see one in this picture, with its jumper for 3.3V or 5V IO

1045×620 115 KB

9

Hi!

it's nice that we have now different solutions for this problem. I hope this will useful for other people with a
similar problem.

I searched hours on the internet for an affordable solution. The cable costs CHF 39.- including shipment and delivery time is one day. When I order something in US then it costs more or less $70 for shipment and delivery time is more than a week. My deadline is saturday 11.19.16!

The Raspberry Pi is NOT my Project, I must only feed the RPi with the data the arduino collects. I have no clue about programming the RPi.

Best regards
Walter

10

I think you would be much better off connecting the serial lines from the mega to the Pi with the two serial pins on the GPIO header. All you need is a potential divider of 1K and 510R on the Arduino's TX pin and don't forget to connect up the ground connections.