Hi guys, I downloaded the i2c libray for the PCF8574 on the arduino site.
but when i upload to my board, nothing shows up on the lcd.
can someone tell me whether im doing something wrong?
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x38,16,2); // set the LCD address to 0x20 for a 16 chars and 2 line display
void setup()
{
lcd.init(); // initialize the lcd
// Print a message to the LCD.
lcd.backlight();
lcd.print("Hello, world!");
}
void loop()
{
}
... I downloaded the i2c libray for the PCF8574 on the arduino site.
but when i upload to my board, ...
Before we can really offer anything other than a guess we will need some more information about your board and a link to the specific library that you used.
Don
http://hmario.home.xs4all.nl/arduino/LiquidCrystal_I2C/
this is where i got my library:)
After you uploaded the sketch, did the LCD make any activity? Did it blink, did it turned on the backlight, ...?
Check the PCF chip if it is 8574 or 8574A as these two have different base address...
Do you use jumpers to modify base address?
Double check wiring...
Did you use pullup resistors for SDA and SCL lines?
...
borntokillyou:
http://hmario.home.xs4all.nl/arduino/LiquidCrystal_I2C/this is where i got my library:)
And you said:-
[I downloaded the i2c libray for the PCF8574 on the arduino site.](http://I downloaded the i2c libray for the PCF8574 on the arduino site.)
Look at the URL, that is NOT the arduino site.
LiquidCrystal_I2C lcd(0x38,16,2); // set the LCD address to 0x20 for a 16 chars and 2 line display
The code and the comment do not match 0x38 IS NOT 0x20
YES! I know i changed it to 0x38
Im very new to this, and I dont really know how to address the i2c.
Im using a pcf8574AP
can anyone advise me on how to use jumper to change the address?
I've been looking all over the net for solutions.
YES! I know i changed it to 0x38
So change or delete the comment.
can anyone advise me on how to use jumper to change the address?
What jumpers you haven't said what hardware you have!
On these chips there are three address lines, you put them to zero or one depending if you need a zero or one in the first three bits of the address.
Use an I2C scan program to see what address your device is currently sitting at. There have been a few posted over the last few months hers, google for one.
It's two days later and everyone is still guessing. We still don't know what hardware he is using and which of the two libraries (that are at the non-Arduino site) he is using.
Don
This is the hardware provided by my institution for me to use. Im actually working on my final year project.
any help would be greatly appreciated:)
borntokillyou:
YES! I know i changed it to 0x38
Im very new to this, and I dont really know how to address the i2c.
Im using a pcf8574AP
can anyone advise me on how to use jumper to change the address?
I've been looking all over the net for solutions.
Well we finally have some of the information we need. We still don't know which library you used which may influence how to deal with the I2C address.
To determine the I2C address:
(1) Look at figure 10 of the datasheet to start to determine the address. You will notice that three of the bits are designated as A0, A1, and A2.
(2) Look at figure 2 to find out which IC pins are used for these three bits.
(3) Look at the bottom of your PC board to determine the logic level of these three bits.
(4) Put those logic levels back into figure 10 to get your actual address.
Don
http://arduino.cc/playground/Code/LCDi2c
this is where i got the library from. its a link from the arduino playgorund, i clicked on the pcf8574.
the ic im using is phillips pcf8574AP, its written on the IC itself.
So what is the logic level on the three address bits, pins 1, 2 & 3 on the chip. From the photograph they don't look like they are connected to anything. Connect them to ground to make the address 0x38.
From the photograph they don't look like they are connected to anything.
That's not what I see, but he is the one with that actual PC board so it should be easy for him to determine how the pins are configured.
Connect them to ground ....
I don't think that would be a good idea. They obviously are already connected to one logic level or another since I don't think the board designer would have left them floating. If they are already connected to VSS then connecting them to ground again won't help. I don't see any pull-up resistors (or jumpers) nearby so if they are connected to VDD then connecting those pins to ground would create smoke and heat.
Someone may give him the answer but in the long run I think he will be better off working it out for himself following my outline.
Don
this is where i got the library from. its a link from the arduino playgorund, ...
Well I followed your link and found that I had to "Download the latest version from here". When I tried that I reached an essentially blank page with a few tiny links in the lower left corner. One of them did nothing and the other wanted me to sign into "Mobile Me". If you think I am going to do that then perhaps you might be also be interested in a bridge that I have for sale. I have moved away from Brooklyn and no longer have any need for the bridge.
Don
