Author Topic: connecting to serial port  (Read 3621 times)

RAWX86

  • Guest
connecting to serial port
« on: March 30, 2013, 10:33:51 am »
Got my Cubie for about a week now, so still new to this...

Since it does not boot from from µSD (tried Berryboot and some pre-made images - no screen on HDMI / no device on local network), I want to troubleshoot via serial connection.

I have poor pure package only. So I had to wire to RS232 myself.
There is connected:

RX > Pin 2
TX > Pin 3
GND > Pin 5

...but I cannot seem to get any messages not on Linux (using screen, like descriped at http://linux-sunxi.org/Cubieboard/TTL) nor Windows using Putty.

Am I missing something, maybe some connection that verifys the Sub-D to be plugged in or something like that?

Any suggestion appreciated...  :)

BigWhoop

  • Guest
Re: connecting to serial port
« Reply #1 on: March 30, 2013, 05:45:24 pm »
which microcontroller do you use for ttl?

RAWX86

  • Guest
Re: connecting to serial port
« Reply #2 on: March 30, 2013, 06:44:12 pm »
which microcontroller do you use for ttl?
The device is displayed as VID_067B&PID_2303&REV_0300 / PL2303...

Maybe that chipset cannot work for TTL?
I am not realy sure if I understand corretly how this works out...  :-\

Thanks.

//edit:

I tried to swap RX / TX - but only getting garbled *** in console...
« Last Edit: March 30, 2013, 06:55:16 pm by RAWX86 »

RAWX86

  • Guest
Re: connecting to serial port
« Reply #3 on: March 31, 2013, 06:00:50 am »
Arg... I have been stupid / should have checked some documentation, before just trying to connect something refering to assignments diagrams...  :-[

As I may not be the only noob around here (at least I hope so), heres the explantion why you cannot use a USB / RS232 for TTL:

https://www.sparkfun.com/tutorials/215


addition / just for fun:

Here in Germany everything is closed until tuesday (easter feasts), no one would ship anything until then, so I decided to do some modification...

I thought it should be possible to grab data signals from the UART before the MAX-232 makes it RS-232 compliant:

Datashet for PL2303HXD is avaible at http://www.prolific.com.tw/US/CustomerLogin.aspx
The connection on IC is TXD / Pin1, RXD / Pin5, GND / Pin 18, I have the GND connector soldered to a  9SD female connector, as it is a little tricky to solder to the IC with a 5mm iron...  ;D



Those converters are about 3€ only and plenty of you may have one laying around, so it is a pretty cheap solution and works like a charm, anyhow I do not recommend it as I badly hurt my finger, when removing the plastic cover with a cutter. XD

Learning never stops.  :)
« Last Edit: March 31, 2013, 09:12:03 am by RAWX86 »