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1  Products / Arduino GSM Shield / Confusing info about serial pin numbers on the GSM shield page on: February 28, 2014, 05:07:24 pm
I am reading the GSM shield page http://arduino.cc/en/Guide/ArduinoGSMShield. There is a photo about the board taken directly above. The text on photo says: GSM TX (pin3) but it easy to see on the photo that it is really RX. The other pin is wrong also. The whole Arduino site seems confusing these.

I am trying to start Itead 3G  modem to communicate with the MEGA, but it is difficult to know what are the RX and TX pins really. They are crossed on the Itead Board. I can say now that Itead's  documentation is not very helpful either. Because of all this I have to trace the connections with a multimeter. I would rather do something else at Friday night.
2  Products / Arduino Due / Re: Parallel library for Due External Memory Bus/Static Memory Controller on: February 18, 2014, 04:58:11 pm
If address pins are missing you will have holes in the space that would cause duplications on top of other data.

So for example if A4 was missing you could write 16 contiguous bytes ok, but the 17th byte will go into location 0, thus overwriting the first byte. This could be manageable but a right PITA.

Likewise with data, the top bits may not matter if you stick to values below the first missing bit, but if you are missing any low-order bits you will be in trouble. This is almost not possible to use unless you "adjust" every variable you save and "unadjust" every variable you retrieve.

______
Rob

I don't think missing address pins cause other problems than a smaller device. For instance a 65000 byte device with 16 address bits. If leave one address pin/bit out, you'll have a device with 32000 usable bytes. If it is a some kind of rom and you connect it to a processor with all address pins, then you'll get gaps (or a great mess, if don't take care). I am not going to draw any truth tables so I leave this here.
3  Using Arduino / Project Guidance / Re: Cannot get 433MHz TX/RX pair to work ! on: February 18, 2014, 04:44:46 pm
Nonsense. I have a Remote running from 3.7V Lipo and a Main box with receiver running form 5V.
Having a higher voltage battery on the Tx would just provide greater transmit range.

Yes of course if you are using that transmitter. But direct pin to pin serial requires same logic levels.
4  Using Arduino / Project Guidance / Re: Cannot get 433MHz TX/RX pair to work ! on: February 18, 2014, 01:25:40 pm
You have been given some very good advise, but what about supply voltages for Unos and Nanos. They must be the same.
5  Products / Arduino Due / Re: Parallel library for Due External Memory Bus/Static Memory Controller on: February 14, 2014, 09:37:32 am
About unusable pins. You can still use external memory if some address or datapins are not available.  If address pin is missing, you just can't use the whole memory space. With missing data pins it is similar.

So we'll have like a 256k 14bit ram or something available, instead of a full 1M 16bit device. But ofcourse cpu with a proper external bus would be nice.
6  Products / Arduino Due / Re: Fast Software Serial (1-1M baud) on: February 03, 2014, 02:31:25 pm
Interesting. Thanks
7  Products / Arduino Due / Re: (Solved) a newly downloaded Arduino 1.5.5 BETA for DUE does not start on: January 31, 2014, 07:20:03 pm
I think I fixed it. At least it works now. I googled the error message and found this and others.
http://forum.arduino.cc/index.php?topic=167553.0
So I deleted all folders called Arduino I could find. I copied my programs elsewhere first. Then I ran CCleaner and deleted all files from C:\Users\XXX\AppData\Local\Temp folder.

Something made it
8  Products / Arduino Due / (Solved) a newly downloaded Arduino 1.5.5 BETA for DUE does not start on: January 31, 2014, 02:01:21 pm
I have twice tried to download and install the Arduino environment for DUE from here. I selected the "Arduino 1.5.5 BETA (with support for Arduino Yún and Arduino Due boards)"

Installation is normal but when I try to start it, I get an error message which says:
An error occurred while starting the application.

I have a Win 7 system and the DUE IDE has worked before in this machine. It has been long since uninstalled.

Edit: I have now tried both zip and install version and they both  have the same problem. With Zip version I also get a note from Windows Firewall but not from installed version.
9  Products / Arduino GSM Shield / Re: Need Help in configuring the 3G/GPRS shield from ITEAD STUDIO on: January 30, 2014, 03:04:21 pm
There is a sample program on Itead's webpage. Have you tried those?
10  Products / Arduino GSM Shield / Re: Sim900 GPRS SHIELD problem help me all? on: December 17, 2013, 04:40:56 pm
You're welcome!
11  Products / Arduino GSM Shield / Re: Code hangs in interrupt when there is poor GSM signal on: December 16, 2013, 08:38:55 am
Perhaps this is a similar problem I had with an other GSM Shield. The shield stopped working after day or two. There was no error messages and no way to tell that it had stopped working. Only way to recover was to shut down the power for a second.
12  Products / Arduino GSM Shield / Re: gsm shield on: December 16, 2013, 08:31:03 am
A wrong number? Does it work the other way around. That is, can you send into your GSM shield?
13  Products / Arduino GSM Shield / Re: Sim900 GPRS SHIELD problem help me all? on: December 16, 2013, 08:28:34 am
Hi. Sometimes weird characters are caused by different baud rates.
14  Topics / Device Hacking / Re: This is what we're missing from the Arduino range! on: November 06, 2013, 04:23:38 pm
Well, beer tastes like ..... But to open a Coca cola bottle you sometimes need a little ingenuity or imagination. When I was young and desperate I found out that a drawers handle was just the tool made for this.

Leif
15  Using Arduino / LEDs and Multiplexing / Re: 10 Watt high power LEDs. on: November 05, 2013, 11:19:19 pm
I found a schematic diagram of a transistor driving LED.
http://www.sqlskills.com/blogs/paulselec/post/arduino-figuring-out-transistors-and-associated-resistors.aspx
Here R1, the collector resistor, limits the LED current. With high current R2, the base resistor, should be smaller and the transistor bigger. Or use a fet.
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