Add-ons

UART - J11 - replacement serial cable

21 16453
TooMeeK  
Post Last Edited by TooMeeK at 2014-8-10 01:24

Hi there,

I'm looking into replacement serial cable to connect to the UART on J11.
I've used serial cable designed for SATA disks, it uses only 2 cables - blue and white.
It's reported under Linux as: plc2303 converter at ttyUSB0
Banana isn't starting when cable is connected to PC and device, it starts however when it's disconnected from Banana.
My thinking was serial cable mean serial, so it should work or my cable is faulty or my settings are incorrect.
I'm receiving something (but unreadable) when cable is connected after boot.

Q:
1. what are correct minicom/putty values?
speed (baud) = ?
stop bits = ?
data bits = ?
parity = ?
flow control = ?
terminal emulation = is VT102 correct?

2. do I really need serial cable? I think UART means it has builtin converter..
so just use standard USB cable with pins
UPDATE:
found something interesting but Raspberry, will it work with Banana?
http://elinux.org/RPi_Serial_Connection
http://codeandlife.com/2012/07/01/raspberry-pi-serial-console-with-max3232cpe/

UPDATE:
replaced blue by green and receiving ureadable data at 115200 baud.. see the screenshots
UPDATE:
3. Can be Nokia CA-53 serial cable used as replacement?
bananaserial.png
bananapiserial2.png
Do You connect Banana Pi GND with USB Serial Converter?

TooMeeK  
No. J11 has only 2 pins - RX and TX.

Post Last Edited by sylwek2k at 2014-8-10 13:14

You must have common ground of Banana and the other device.

Connect:
banana pi RX with TX port of converter,
Banana pi TX with RX port of converter,
GND of banana with GND of converter.

Remember, that Banana Pi work with 3.3V standard of input and output...

TooMeeK  
Post Last Edited by TooMeeK at 2014-8-10 14:42

So J11 cannot be used. Which one then?
J12 pins:
J12 Pin2 - 3.3V
J12 Pin4 - RXD - UART7_RX
J12 Pin6 - TXD - UART7_TX
J12 Pin8 - GND
Are they correct? I have 4 cables coming from converter:
red, green, blue, white I don't see which one is GND (blue?)
UPDATE:
Here's its datasheet:
http://www.cutedigi.com/pub/BB/TTL_USB/pl2303.pdf
UPDATE:
Dissasembled the cable.. and discovered that red wasn't even connected to the chip..
20140810_143928.jpg
20140810_143938.jpg

You may use J11 connector, but You must have common ground for this 2 device. You may get power banana from computer (then You have already common ground), You may get power from other power supply, but You must connect ground from banana and conventer.

I wrote about 3.3V input and output, becouse, if You connect 5V signal to the banana pi uart You may distroy the chip. Pin 4 of pl2303 should be connected to 3.3v in banana pi.

I don't know, which color of Your converter is connected to each part of pl2303, becouse there is no standard...

TooMeeK  
From the Profilic's datasheet I see I suppose to connect pins:
1 TXD O Data output to Serial port
5 RXD I Data input from Serial Bus
17 VDD_3V3 P 3.3V power for USB transceiver
18 GND_3V3 P 3.3V ground

to J12 to get fully powered and grounded device, is that correct?

TooMeeK  
Post Last Edited by TooMeeK at 2014-8-10 15:04

RX and TX cables are switched in pairs as You said:
Connect:
banana pi RX with TX port of converter,
Banana pi TX with RX port of converter,
GND of banana with GND of converter.

what about power? Red to Red, GND to GND?

TooMeeK  
Post Last Edited by TooMeeK at 2014-8-10 18:27

Thank You!! You solved my issue.
I'm receiving syslog messages
- power for Banana from laptop, plc2303 connected to laptop
- green cable from Profilic to Banana's J11 RXD
- white cable from Profilic to Banana's J11 TXD

Now I just need to find a way to use all 4 cables..
EDIT:
Blue cable on Profilic device was connected to:
15 DP I/O USB DPLUS signal

should be GND here
EDIT:
Yep, got GND check via multimeter, located where pin GND_3V3 comes from on Profilic, it's connected to USB header.
So here's my GND. No need to have +3.3V ? it shows log on console (screen) until serial reached and then stops.
Banana boots normally when cable isn't connected to RX/TX on J11.
Should I use UART RX/TX from J12 or just need VDD_3V3 connected too?
bananapi-serial-grounded.png
20140810_172410.jpg

TooMeeK  
Why Lubuntu stops booting with serial cable connected? See the log.
[uart]: serial probe 0 irq 33 mapbase...

You have to log in before you can reply Login | Sign Up

Points Rules