Arduino + Nokia LCD3310

Hello,

I recently found a Nokia 3310 LCD (PCD8544). I used the examples given here: http://www.arduino.cc/playground/Code/PCD8544 And managed to talk to the LCD. The wiring scheme is the one in the example.

But here come my questions: 1) how do I print on the LCD a value measured at the analog pin A0? For example, if I measure a 2.32 V value on the A0... how do I print that on the LCD, given the fact that the example works with char's ?

2) How do I output on the LCD a graph ? For example: I want to measure continuously a value from pin A0 and display it as a graph to view the way the signal modifies.

Thank you, A.

To turn a nibble into a char simply logical or it with 0x30; So if you have a byte value in a variable called val then:- char char1 = (val >> 4) | 0x30; // use the top nibble char char2 = (val & 0xf) | 0x30; // use the bottom nibble see:- http://www.arduino.cc/playground/Code/BitMath

Second question is simply a matter of using the variable value to control the position (say the Y position) of a graphic on the screen.

Thank you for the reply.

If I understand correctly, "val" is the value I read from the A0 input (in my case), but what I don't understand is why use only top nibble (if I remember correctly, a nibble is represented by 4 bits of a byte ). As far as I could test, it only prints on my LCD integer values. I made val = 5.35 and on the LCD I got 5. Negative values are not being printed.. just some unreadable character. If I use this piece of code: gotoXY(24,3); LcdCharacter(ASCII2[5]); LcdCharacter(0x2e); LcdCharacter(0x33); LcdCharacter(0x35); It prints 5.35 whitout a problem... however this is static.. I need to change it.... Is there any function similar to itoa that works with fractional values ?

A.

I made a breakthrough. After a lot of searching, I managed to find this PCD8544 library. in the example code supplied with this library it is demonstrated the reading of a temperature from analog pin and print to LCD.

http://code.google.com/p/pcd8544/

A.

Although I resolved the issue with the LCD display, now I find myself in another situation: how do I measure a negative value with Arduino, since it cannot measure negative values ?

I was thinking of using an operational amplifier as a voltage comparator but I have no idea how to make the circuit itself. I want to compare the signal input with 0 and when I get the biggest value... then pass it through another op amp connected (i suppose it's simpler) as a inverting voltagr follower to invert the sign.

I guess I hit a big wall... and... don't know how to get out... Hope someone can help.

Thanks, A.