lilzz
Posts: 411
Joined: Sat Nov 30, 2013 5:27 pm

Installing a CP210x USB to Serial converter

Fri Apr 29, 2016 7:18 pm

dmesg | grep tty
usb 6-2: cp210x converter now attached to ttyUSB0


then I started Putty
Putty configuration
/dev/ttyUSB0 baud:9600

connect (open)

But it complains unable to open serial port.

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B.Goode
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Re: Installing a CP210x USB to Serial converter

Fri Apr 29, 2016 8:21 pm

Maybe the user account you are using does not have permission to access /dev/ttyUSB0 ?

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scruss
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Re: Installing a CP210x USB to Serial converter

Fri Apr 29, 2016 9:30 pm

Yes, that's most likely. I've used CP210s without problems, and your system looks like it is doing the happy thing.

Check for this:

Code: Select all

$ groups
pi adm dialout cdrom sudo audio video plugdev games users netdev input indiecity
[email protected] ~ $ ls -la /dev/ttyUSB0 
crw-rw---T 1 root dialout 188, 0 Mar 28 11:45 /dev/ttyUSB0
You need to be part of the ‘dialout’ group to have read/write access to the serial port.
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.

lilzz
Posts: 411
Joined: Sat Nov 30, 2013 5:27 pm

Re: Installing a CP210x USB to Serial converter

Sat Apr 30, 2016 11:09 pm

well, I did
groups
lilzz adm sudo dip plugdev lpadmin

so, I added

useradd -G dialout lilzz

but it complains
useradd: user 'lilzz' already exists

lilzz
Posts: 411
Joined: Sat Nov 30, 2013 5:27 pm

Re: Installing a CP210x USB to Serial converter

Sat Apr 30, 2016 11:17 pm

I can't add myself to dialout group.
sudo usermod -a -G dialout lilzz

then I check with groups
dialout still not there

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scruss
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Re: Installing a CP210x USB to Serial converter

Sun May 01, 2016 12:09 am

you need to log out and log back in again
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.

lilzz
Posts: 411
Joined: Sat Nov 30, 2013 5:27 pm

Re: Installing a CP210x USB to Serial converter

Sun May 01, 2016 8:36 pm

OK, my putty is finally launched now.

but it's a blank. it has a small green rectangular shape and nothing else.

I try to type in something but nothing shown.

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scruss
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Re: Installing a CP210x USB to Serial converter

Mon May 02, 2016 3:27 am

Is the device you're talking to really 9600 baud?
Have you crossed TX with RX, and vice versa, to make the null modem connection work?
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.

lilzz
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Joined: Sat Nov 30, 2013 5:27 pm

Re: Installing a CP210x USB to Serial converter

Mon May 02, 2016 7:45 pm

OK, I got something back like this.

But I can't type any command. What does this mean from the picture I shown? Is the communication OK? I attached a ESP8266 wifi module to the CP201x.
Attachments
putty1.jpeg
putty1.jpeg (8.42 KiB) Viewed 2413 times

DirkS
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Re: Installing a CP210x USB to Serial converter

Mon May 02, 2016 8:17 pm

lilzz wrote:I attached a ESP8266 wifi module to the CP201x.
Apparently the default rate may depend on the firmware version (although the ones I have all started off at 9k6)
Try higher speeds, up to 115k2.
Another thing to be aware of is that ESPs expect a CR+LF for entering commands. I'm not sure if Putty does this by default.

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DougieLawson
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Re: Installing a CP210x USB to Serial converter

Mon May 02, 2016 8:31 pm

That sort of error usually means the baud rate is wrong.
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lilzz
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Re: Installing a CP210x USB to Serial converter

Wed May 04, 2016 9:22 am

Ok, I set the baud rate to 115200, I see something now.

but I type AT, and hit enter button.

I expect to see OK as response but nothing happened.

what's CR+LF? same as enter button?
Attachments
putty2.jpeg
putty2.jpeg (10.14 KiB) Viewed 2264 times

DirkS
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Re: Installing a CP210x USB to Serial converter

Wed May 04, 2016 9:45 am

lilzz wrote:what's CR+LF? same as enter button?
No, that depends on the system.
You will have to make Putty send both a carriage return and a linefeed when you hit enter.

IIRC There are settings in Putty about implied linefeed when sending, but I'm not 100% sure about that.

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