www.8devices.com
View unanswered posts | View active topics It is currently 28 Mar 2024, 16:02



Reply to topic  [ 6 posts ] 
 Serial and WiFi connection issues 
Author Message

Joined: 31 Dec 2014, 13:22
Posts: 3
Hi all,

I've bought my carambola module more than one year ago - finally I could have a look at it these days but I wasn't that successful:

First the hardware: As I didn't buy the developer board, my Carambola has 5 pins directly connected: pin 22/23 and 24 are connected to a 3,3V LM2596 switching Regulator.
The serial connection is made through pin 35 and 36 (pin 31 and 32 didn't work), followed by a MAX3232 closely soldered to keep unshielded cable length short and a PL2303 Serial to USB adapter.
The shield which was shipped with the module is also properly soldered. The MAX3232 and the LM2596 are ready to use modules bought on ebay.
Used software is Putty on Win7 64bit, settings are 115200,8N1,no Flow control.

First problem: I can read everything sent from Carambola to Putty without any error, but when I type something, random chars appear. Sometimes it works pretty well for a few minutes, but most of the time I cannot enter any command. For example, I press "aaa" and I receive "sA@". I have replaced both MAX3232 and PL2303 without success. I also tried several PC, it works on an old XP laptop slightly better but this could be also wishful thinking.
I don't have any idea what else I can do. I just wonder why I had to use TX2/RX2 instead of TX/RX.

Second problem: I finally managed to remove the option disable line and activate WiFi. I can logon with browser, putty, winscp over wifi, but connection is not stable. After some seconds of activity all Software disconnects, pings time out. WiFi keeps being connected. After some time (around one minute), pings return and I can reconnect the software. Serial connection works flawlessly during these WiFi timeouts, a parallel output of an ls command was not interrupted or even slowed down.

My last idea was upgrading the firmware: I've downloaded from http://pkg.8devices.com/?dir=carambola/ ... pgrade.bin 2014-08-13

After several attempts I could transfer the file via WinSCP to Carambolas /tmp folder and I was able to start via serial the sysupgrade -v -n /... command, Carambola worked, rebooted - and no change. Both issues remain.

I am now running out of ideas, any help, suggestion, whatever is deeply appreciated.

Thank you very much!
best regards
frank


03 Jan 2015, 00:56
Profile

Joined: 11 Jun 2014, 14:45
Posts: 135
Deleted my previous post, as I incorrectly was thinking (and answering) about Carambola 2.


05 Jan 2015, 08:50
Profile

Joined: 11 Jun 2014, 14:45
Posts: 135
Both Carambola module and PL2303 seems to use TTL logic levels (http://www.electronicaestudio.com/docs/PL2303.pdf) so my questions is why are you using MAX3232?

As for the Wifi are there any messages in the console (dmesg) and does your module have integrated antenna?


05 Jan 2015, 09:02
Profile

Joined: 31 Dec 2014, 13:22
Posts: 3
Hi,

thanks for answering! Sorry that I didn't make that clear enough: With PL2303 I meant a full USB to RS232 adapter, not only the PL2303 chip.
I mentioned the PL2303 because I've read somewhere that it is strongly recommended to use an USB to RS232 adapter based on this particular chip. RS232 works at least with +-3V so MAX3232 was necessary.

Dmesg shows nothing more than the boot messages and yes, I am using integrated antenna only.

It might be a good idea to say right now that I don't have any experience in any linux-like system, I even wasn't aware that the command dmesg exists. I've only checked logread (which also shows nothing). Is there maybe more what I could check?


Stuck Frank
but hope never dies;-))


06 Jan 2015, 22:42
Profile

Joined: 11 Jun 2014, 14:45
Posts: 135
At this moment I can't think of anything specific to your problems. Random things that could be checked are:

1) Measure if there are any voltage spikes on power supply (or -ies if there are few of them chained). Change power supply, if possible use Lab power supply.
2) Detach MAX3232 from Carambola and shortcircuit TX and RX lines (hardware echo) and check with putty that the correct chars come back. Make sure that MAX3232 and Carambola use the same voltage levels. Change serial adapter (to one that has TTL voltage levels instead of RS232). If possible use logic analyzer to capture signals.
3) Reduce WiFi output power and put laptop/wifi adapter away from Carambola module. Power Carambola separately from the laptop/PC that is used to debug.


07 Jan 2015, 09:23
Profile

Joined: 31 Dec 2014, 13:22
Posts: 3
as an intermediate Report:

Used a lab power supply, no change. Connected tx rx, after adding a pullup resistor it worked perfectly.
Reducing carambolas tx power and moving laptop away didn't change anything.
So i suppose carambola is defective and i will order a new one.

Will report results once i've tested the new one.
Frank


15 Jan 2015, 13:53
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 6 posts ] 

Who is online

Users browsing this forum: No registered users


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron

Protected by Anti-Spam ACP Powered by phpBB® Forum Software © phpBB Group
Designed by ST Software.