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976  Using Arduino / Project Guidance / Re: serial to PC instead of SD card logging on: August 11, 2012, 06:30:32 am
The ftdi cables are expensive here, and I am sending the complete prototype unit to a friend upcountry, so if they have a simple terminal program ( like MegunoLink ) and set it for 9600 and no handshaking .will they be ok with just my sending a string via the TXD to the PCs RXD in ( at the right level ? )

It will generally only be a couple of times a minute I guess.

Presumably they can either check for serial in every loop ?

PS   John Boxall in his excellent Tronixstuff course suggests using MegunoLink as a data logger instead of the SD Card ( obviously if there is a PC handy )
977  Community / Bar Sport / Re: OMG ! I am a God Member ! on: August 11, 2012, 05:59:12 am
I agree too, congrats NI$HANT but it gets a bit hard for an old fart like me to rank our heros like Tesla etc in any order ( and some I must confess I dont remember :-)
978  Using Arduino / Project Guidance / Re: serial to PC instead of SD card logging on: August 10, 2012, 04:32:58 pm
I am not using the Arduino for the project, just the 386 on a minimum pcb, so USB would be a bit more complicated than a simple MAX232 chip to connect to the monitoring PC ?
979  Using Arduino / Project Guidance / Re: COMPLETELY NEW user of Arduino/electronics/etc on: August 10, 2012, 04:17:35 pm
If you have strings of say 5 LEDs in series running off a 12v supply, the voltage across them ( for red LEDs ) will be about 9.5 volts, and  you could use a  120  ohm resistor to limit their current to about 20 mA  (  12v supply , minus the 9.5v across all the LEDs  =  2.5 volts / 0.02 amps  ( ohms law ) = 125 Ohms )

BUT  this only applies if the 12 volts is regulated , if the supply is taken directly from the car battery it can go up to 14 volts, giving you ( 14 - 9.5v   =   4.5 / 120 ohms  = )  37 mA through all the LEDs which will release their magic smoke, or make them go dark :-)

I always use a 12v regulator for every 1 amp bank of LEDs displays.  ( and I only run the LEDs at 18mA which I find a reliable level - out of the last 50,000 LEDs in 3 years I have only had about 6 LEDs fail - excluding orange ones which I had bad luck with for some reason ! )
980  Using Arduino / Project Guidance / Re: serial to PC instead of SD card logging on: August 10, 2012, 02:58:50 pm
Thanks Wanderson,   very interesteing about the packet size for saving on SD cards,   I will try that on another project I have that uses cards.

Now its up and running, I see this project needs the realtime data to a screen.

I am using the 328 chips on small pcbs ( I just use the Arduino for testing and programming )  and the RXD pin of this logger unit I am using to receive from the 2.4GHz receiver, (  I could change that to a SoftSerial pair of pins )

If I have a D9 serial connector, do I need to connect more than TXD and ground ?  ( I am not sure about the RTS and CTS etc pins )
981  Using Arduino / Project Guidance / serial to PC instead of SD card logging on: August 10, 2012, 11:04:44 am
My queueing project is working, recording data from 7 units via wireless links.

I am not happy with the SD card reader for logging , partly becuse I think the time it takes to write each time is making it miss some of the incoming data, and partly because there is no realtime info.

I want to change it to a simpler system that outputs a serial CSV string to a PC via a RS232 serial link, every time a button is pressed.

I am just learning about Serial comms.

Can I just use TXD and RXD through a MAX232 level converter to a 9pin serial connector ?

In fact can I just use the TXD  ( I want to use the RXD for one of the radio link inputs )

Just need a bit of guidance before I fire up the soldering iron...
982  Using Arduino / Project Guidance / Re: Money Slot detector (IR / combining analog inputs) on: August 10, 2012, 10:27:05 am
You could have a line of LEDs illuminating a load of cheap LDRs connected in series.

If you use white LEDs rather than IR,  it would light up the slot ?

The top LDR is connected to Vcc  ( 5v ) and the bottom one to a 220k preset pot that goes to ground.

With nothing breaking the beam ( all the LDRs at low resistance ) set the preset so that the voltage at the bottom of the LDRs is 2.5v

Connect this point to one of the analog inputs of the Atmega 328 - or arduino board -  with a 100 nF capacitor to ground to smooth out any noise.

With you thinnest bank note in the way ( which should weaken several of the beams ) measure the voltage on the analog pin, and write your sketch to detect an object if the voltage drops below this level ( leave a margin spare for ambient light noise )

The idea is that with all the LDRs illuminated, ( say there are 10 of them with 3 kOhm resistance  illuminated ) , the total resistance will be 30k.
As soon as even one of the LDRs is shaded, it goes up to perhaps 100k resistance, making a series resistance of 127k,  more than enough to detect.
983  Community / Bar Sport / Re: Ardunio C++ ROCKS ! on: August 04, 2012, 02:36:35 pm
984  Community / Bar Sport / Re: Ardunio C++ SUCKS!!!! on: August 04, 2012, 10:19:29 am
Very interesting Michael,

and frightening,  I am so glad now that I never volounteered for a shuttle flight !
985  Community / Bar Sport / Re: OMG ! I am a God Member ! on: August 04, 2012, 08:20:41 am
Thanks guys, I hope to have a bit more time for the forum soon ( got 4 simultaneous orders out this week, after 2 months without a day off )

My next project is going to be a wireless mesh thingy, using the SIM20 modules.  I bought a couple, but the technical info is attrocious, so I will experiment and see.

No doubt I will be " phoning a friend" again on the forum !
986  Community / Bar Sport / Re: Ardunio C++ SUCKS!!!! on: August 04, 2012, 08:17:05 am
I was working at a NASA tracking station in the UK when I did a ( 2 days )familiarisation  course  in Fortran ( 1968  )
I assume we were using it for satellite predictions ...
987  Community / Bar Sport / Re: Ardunio C++ SUCKS!!!! on: August 04, 2012, 08:13:31 am
Είμαι βέβαιος Arduino είναι εξίσου εύκολο στην ελληνική γλώσσα  !
988  Community / Bar Sport / Re: Ardunio C++ SUCKS!!!! on: August 03, 2012, 05:16:36 pm
Thats great, perhaps you could get to adding some help for newbies from the same background experience ?

When I get a chance, I want to post a couple of things for techies from my " soldering iron" background , explaining why pin2 is actually pin 4, and pin 28 can be analog 5 or digital 19 ( took me a while ) and so on.
989  Community / Bar Sport / OMG ! I am a God Member ! on: August 03, 2012, 09:57:28 am
Due to my 500 times that I have had to ask for help - and the odd times that I could offer advice to REAL newbies  - I have been promoted to GOD member !     I didn't even get through Angel member   !!

 - I am so humbled, and never again will you read in my postings things like OMG, or anything frivalous, or will I omit the second equals sign ........
990  Community / Bar Sport / Re: Ardunio C++ SUCKS!!!! on: August 03, 2012, 09:49:13 am
On the contrary ( to the original subject  )- Arduino Rocks !!

I am also an old fart ( 64 in your Earthling years ) who had come through valves ( tubes ) transistors, TTL and found myself stuck for 20 or more years at CMOS logic, scared to move further on than my Sinclair 32 computer.

Ok I played with a bit of basic, and I wrote a simple FORTRAN program on a course in 1968, but just couldnt get into the micro scene - until I found Arduino in 2010 !

Now I am building all sorts of ambitious projects that tax my lateral thinking, but thank heavens for the guys on the forum that point out the brain farts in my code.

The project I finished today, I could never have contemplated in my CMOS days  -   A queueing system with a GPS receiver, thermal printer, 2.4 GHz link to a data logger ( SD card ) which also receives and logs data from 6 remote controls via a 433 MHz link ( which also has to be displayed on a LED dsiplay )
 I came up with my own system to save data to eeprom on all the units if the power goes down - probably twice as complicated as what might be available doing a search, but it works great and brings me so much satisfaction !

So I think that what SUCKS !!!!! was my reluctance to get into micros all this time, and what ROCKS !!! is the gateway that these Italian guys thought of in a bar called Arduino ,   Grazie per l'introduzione di microprocessori !!!

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