Madaeng
Posts: 6
Joined: Tue Jun 11, 2019 6:15 pm
Location: Netherlands

Need help establishing a serial connection

Tue Jul 09, 2019 1:27 pm

Hi all,

I'm currently working on a project to integrate a pi zero W in my neato Botvac.
Connecting it by way of a USB cable was pretty straightforward, tried that out according to this method: https://www.instructables.com/id/How-to ... pberry-Pi/

However, since I want to be able to use it differently then in that thread, the USB port was not an option as that didn't fit with the dust bin in.
So, I decided to use the RS232 port on the BotVac board instead, connecting the pi's UART port with a MAX3232 board
https://www.sparkfun.com/products/11189
to convert the signal suitable for the RS232.

The MAX3232 draws its power from the pi and everything is hooked up as follows, with the only differences being that I used the 3V3 pin on the pi, and I don't utilise the 'bottom' part of the BotVac board.
Image
Image
Image

I've disabled the terminal on the pi, and tried to connect to the BotVac using

Code: Select all

sudo screen /dev/ttyS0
(instead of

Code: Select all

sudo screen /dev/ACM0
)

However, whenever I try this, screen is non-responsive to any input and I have to CTRL-A CTRL-D out of it. I figured I may have switched the rx&tx, but switching those is to no avail either.

Does anyone have any clues on where the problem may lie?

Milliways
Posts: 426
Joined: Fri Apr 25, 2014 12:18 am
Location: Sydney, Australia

Re: Need help establishing a serial connection

Wed Jul 10, 2019 6:20 am

Pin 8 is Serial Output
Pin 10 is Serial Input

Madaeng
Posts: 6
Joined: Tue Jun 11, 2019 6:15 pm
Location: Netherlands

Re: Need help establishing a serial connection

Wed Jul 10, 2019 7:28 pm

Milliways wrote:
Wed Jul 10, 2019 6:20 am
Pin 8 is Serial Output
Pin 10 is Serial Input
I triple checked, ànd tried switching the wires just to make sure. That’s not the problem.

I read something about baud rate. Is there a possibility that that causes the complete lack of response?

User avatar
B.Goode
Posts: 8058
Joined: Mon Sep 01, 2014 4:03 pm
Location: UK

Re: Need help establishing a serial connection

Wed Jul 10, 2019 8:08 pm

I read something about baud rate. Is there a possibility that that causes the complete lack of response?


If you are using asynchronous communication, having matching baud rates on the receiver and transmitter is absolutely fundamental in being able to transfer data or messages.

So yes, this is a possibility.

Madaeng
Posts: 6
Joined: Tue Jun 11, 2019 6:15 pm
Location: Netherlands

Re: Need help establishing a serial connection

Thu Jul 11, 2019 9:49 am

Turns out I got some bad information and didn't need the MAX3232 at all.
Serial port is probably fried, back to the drawing board....

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