Hey everyone! I have a question, I am compleatly new to the world of arduino. I have done some research but im still on clear on a few things.
The first question i have is: I will be needing Arduino Ethernet Shield I found this one RadioShack.com Official Site - America's Technology Store What i will be doing with this is using it to connect to a mysql db and reading values with in that.
With that said will the Arduino Ethernet Shield that i picked out work with both the Arduino Uno REV 3 or Arduino Mega 2560 REV3?
I just ordered LCD Keypad Shield Module F Arduino Duemilanove LCD1602 on ebay http://tinyurl.com/d9g9xeh
I will be integrating this onto the project along with some led's and possibly a relay.
if you are not going to use the SD card on the shield, you will have maybe 10k left of program space just using the ethernet shield. If you are going to use the SD card as well, use the mega.
if you use that lcd keypad, you will need to disconnect pin 10, which will just keep the backlight on.
since you are already looking on ebay, you can get the ethernet shield for $13 or less there and mega for around $30.
Kelly:
What i will be doing with this is using it to connect to a mysql db and reading values with in that.
I hope you aren't planning on talking to the mysql server directly.
The Uno has 2K of RAM while the Mega has 8K of RAM. An application client to talk to mysql could probably consume that before you start doing anything else with the microcontroller.
If i am looking at the Ethernet card right it looks like it has a SD card slot on it, can i just put a 1 to 8 gb sd card on that to make it work?
If not do you have another suggestion on reading the data from mysql.( i was originally going to access it directly )
doughboy:
if you are not going to use the SD card on the shield, you will have maybe 10k left of program space just using the ethernet shield. If you are going to use the SD card as well, use the mega.
if you use that lcd keypad, you will need to disconnect pin 10, which will just keep the backlight on.
since you are already looking on ebay, you can get the ethernet shield for $13 or less there and mega for around $30.
Kelly:
If i am looking at the Ethernet card right it looks like it has a SD card slot on it, can i just put a 1 to 8 gb sd card on that to make it work?
If not do you have another suggestion on reading the data from mysql.( i was originally going to access it directly )
SD cards aren't used as RAM. You can transfer data to/from them, but only in blocks less than the RAM you have available. If you can't get what you need done in the Mega's 8K of RAM, you might reconsider basing your project on a microcontroller.
XML is very string/text heavy. I would never recommend processing an XML file on an Arduino. Again, you only have 2K (or 8K on the Mega) of RAM available. Just for a reference on how small this is, your last post takes up almost 1kilobyte.
What is it you are trying to do with the Arduino, on a high level?
No pin 10 was also intended as a PWM control lead for the backlight but the fab shop put a bi-polar transistor in instead of a small Mosfet and it is almost impossible to change it out as the LCD is soldered to the board... no pins and sockets. It would Work I suppose but then pin 10 can't be re-used...
Id------name------item_num-----payed
1 Kelly 287504232 1
2 Bill 845245828 0
Note: That 1= payed and 0 not payed.
Then what i would like the arduino to do is loo at this data base and see if there are and unpayed (0's) if so i would like the arduino to show how many 0's there are and display them on the LCD screen i ordered. and at some point sooner then later i would like to to flash a few led's and or work a relay that would control a buzzer or something along those lines for notification.
Do not try and process the data on the Arduino. You simply don't have the RAM.
Instead your Arduino should query a simplified server on a PC (or wherever the mysql database is sitting) and receive what data should be displayed. I would return that data in as small of chunk as possible and simplified as possible. E.g. if you have a 2 line LCD, only have the PC provide the 2 lines and do so in a CSV style format.
The Arduino is a microcontroller, it is meant for controlling things. It is not a microprocessor.
So i think i figured it out... If I have a Computer do all the heavy lifting with php and my sql and then simply have my computer create the CSV file with the value that i want and let the arduino deturmin if the value is greater then 0 then do what i want it to...? Does that sound about right?