I already did that. Now everything works
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| First Steps - Serial Connection won't work https://www.8devices.com/community/viewtopic.php?f=1&t=145 |
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| Author: | Fred Edison [ 06 Jul 2012, 10:03 ] |
| Post subject: | First Steps - Serial Connection won't work |
Hello there, I got my Carambola yesterday and since then I'm trying to connect to it via Serial, but for some Reason it won't work at all. My Setup looks like this: At first I have no Dev Board. I have a connected to Tx2(Pin35) and Rx2(Pin36). The Bus Pirate also provides the 3,3V which is connected to Pin22 and of course Ground of the Bus Pirate is connected to Pin24. When I power it up the Led goes on, but I get silence on the Serial Connection. I tried reversing the Pins, using the other two Serial Pins(and also those reversed) and I even hooked it up to my Oscilloscope to see if there is something going on on one of these four Ports, but besides some little Peak while powering up I still got nothing. I've seen a Setup in another thread where the Terminal Connection is made with the second pair of Serial Pins, so I think the upper ones are the right ones. After looking at the Dev-Board Schematics I thought that the Problem could be that I need to Pull up the Reset Pin, which I then tried, but it didn't make any difference. The only thing I could think of is, that the Bus Pirate cannot provide enough current for the Carambola to function properly, but I also tried using the 3,3V provided by an Arduino which got me the same result. The Arduino was powered by an external power supply which can put out up to 1A so that shouldn't be the problem. So is there anyone who can tell me, what I am doing wrong? Greetings Fred |
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| Author: | Sprite_tm [ 06 Jul 2012, 14:28 ] |
| Post subject: | Re: First Steps - Serial Connection won't work |
You should be able to get the Carambola running with just 3.3V and a serial port. Are you sure the Bus Pirate supports the 115200 baud the Carambola outputs data on? |
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| Author: | NaYthan [ 06 Jul 2012, 15:58 ] |
| Post subject: | Re: First Steps - Serial Connection won't work |
Yes indeed, the serial terminal UART lines are the ones closest to the WiFi antenna (Pins 36 & 35 according to the Carambola Datasheet Pinout picture). Stupid question, did you connect both 3.3V inputs and all of the GND pins on the Carambola? Make sure you haven't overlooked any. Also check for short circuits in your setup. How long did you leave the Carambola on to check for communication? First thing that starts is the uboot boot loader, which waits about 4 seconds for user input from the serial console (so in those 4 seconds there is very little traffic) and then the system boots up. The system boot up doesn't take too long, a few seconds up to 30 seconds (depending on your configuration, but since this is a fresh and unconfigured board I'd say you're looking at less time rather than more time). The Carambola consumes up to 2.5W power. You can search the forum about the exact current that's being drawn by the Carambola, but I believe it was somewhere at or above 500mA @ 3.3V. And it should be a clean supply of course. |
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| Author: | Fred Edison [ 06 Jul 2012, 16:41 ] |
| Post subject: | Re: First Steps - Serial Connection won't work |
Alright, today I tested it with a dev Board and it works fine. And after reading it seems like the Arduino 3,3V Pin can't draw that much current either so the problem is at the power supply. Now I have to look for another power source. |
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| Author: | NaYthan [ 09 Jul 2012, 07:24 ] |
| Post subject: | Re: First Steps - Serial Connection won't work |
You can easily build your own. Just use a 1A 3V3 voltage regulator for the Carambola. |
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| Author: | Fred Edison [ 09 Jul 2012, 09:06 ] |
| Post subject: | Re: First Steps - Serial Connection won't work |
I already did that. Now everything works
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