How to control I2C1 for SunFounder I2C LCD2004

[YSDK001]

This is the first Question for arduino-pico Discussion. Below code is for SunFounder I2C LCD2004 (20x4 line) connected to I2C0/I2C1 pin of pico W.
"Code for I2C0" works well. LCD2004 shows the characters, namely
1st line: Hellow World !!
2ne line: How are you ?
3rd line: What is your name ?
4th line: How old are you ?

But "Code for I2C1" does not works well. Although I can compile "Code for I2C1" without warning or error, I cannot see any character on LCD2004 display.
I would like to show characters like "Code for I2C0" on LCD2004 display, which is connected to SDA and SCL of I2C1 of pico W.

Please advise me.
How do you modify "Code for I2C1" ?

Any advise make me pleased.

// Code for I2C0 ---------------------------------------------------------
//SunFounder I2C LCD2004 (20x4 line) for I2C0 pin of pico W
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,20,4); // set the LCD address to 0x27

void setup()
{
// I2C pin set
Wire.setSDA(16); // 21pin(pico W): GP16 I2C0 SDA
Wire.setSCL(17); // 22pin(pico W): GP17 I2C0 SCL
Wire.begin();

lcd.init();

lcd.backlight();
}

void loop()
{
lcd.setCursor(0,0); //1st line
lcd.print ("Hellow World !!");
lcd.setCursor (0, 1); //2nd line
lcd.print ("How are you ?");
lcd.setCursor (0,2); //3rd line
lcd.print ("What is your name ?");
lcd.setCursor (0,3); //4th line
lcd.print ("How old are you ?");
}

/*
// Code for I2C1 ---------------------------------------------------------
//SunFounder I2C LCD2004 (20x4 line) for I2C1 pin of pico W
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd1(0x27,20,4); // set the LCD address to 0x27

void setup()
{
// I2C pin set
Wire1.setSDA(14); // 19pin: GP14 I2C1 SDA
Wire1.setSCL(15); // 20pin: GP15 I2C1 SCL
Wire1.begin();

lcd1.init();
lcd1.backlight();
}

void loop()
{
lcd1.setCursor(0,0); //1st line
lcd1.print ("Hellow World !!");
lcd1.setCursor (0, 1); //2nd line
lcd1.print ("How are you ?");
lcd1.setCursor (0,2); //3rd line
lcd1.print ("What is your name ?");
lcd1.setCursor (0,3); //4th line
lcd1.print ("How old are you ?");
}

*/

[Andy2No]

You'd need to tell the lcd1 object to use Wire1 instead of Wire.

Maybe the LiquidCrystal_I2C class has a method to set that, or a constructor option?

[Andy2No]

Assuming I've found the right repo for the one you're using, there was a pull request to add support for Wire1, but it still hasn't been accepted:

johnrickman/LiquidCrystal_I2C#16

However, you could fork your own version and maybe merge that pull request, or you could just download the library and either install your own copy, then edit it, or just place the library files in your project folder, exit the IDE and then start it up again. Then change the include from #include <LiquidCrystal_I2C.h> to #include "LiquidCrystal_I2C.h" (quotes for a local path instead of angle brackets).

You can then edit the .h and .cpp files to get it to do what you want. Maybe add a pointer to the wire object to use to the class, and add an optional parameter to specify that, in the constructor, then look through the code for references to Wire and change them to use that pointer instead.

[YSDK001]

Thank you for the contrast advice.
The picture attached is the Back side of the board of SunFounder I2C LCD2004. You can see the the potentiometer for contrast.
The reason of " I cannot see any character in SunFounder I2C LCD2004 display " is not High contarst, I think. I can adjust the potentiometer as I can see th Characters.(Please see attached picture)

[Andy2No]

I'm not clear what the second picture is showing. Was that with it wired to I2C0?

Maybe it's an illusion, but that looks like GP16 an GP17.

Is that display running on 3.3V or 5V? You can run into problems if it's 5V, though I don't know why there would be a difference between the two sets of pins. I've used a logic level shifter to connect a 5V display to 3.3V devices. Character LCD displays like that one often only run on 5V, and when they run on 3.3V or 5V, they sometimes give a clearer display on 5V.

Have you tried running an I2C sniffer sketch to see if the Pico W detects the i2c interface of the display? There's an example here:

https://forum.arduino.cc/t/raspberry-pico-setting-sda-scl-using-arduino-ide/932218

You'd have to edit it to use Wire1, of course.

You could try using a slower clock speed. As far as I know, it defaults to 100,000. I don't know what lower speeds the Pico W supports though, you'd have to look that up or maybe read the datasheet. The way to set the i2c clock speed is Wire1.setclock(speed); which you'd need to place just after lcd.init(Wire1);

Naturally, check your wiring and also check that all the connections are working as you expect. Breadboards can have bad or intermittent connections quite often due to poor quality spring contacts. I've bought quite a lot of cheap breadboards which turned out to be too unreliable to use. The power rails down the sides are usually the worst part.

There's a limit to how much help I can give when I can't physically touch the hardware, and I don't own either a Pico W or one of that particular display, so I'm not sure how much I can help beyond what I've said already. These things don't always work straight away. You may have to do some googling and manual reading. You could consider posting in the Arduino forum too.

[YSDK001]

Thank you for good supply voltage advice.
I adopted your advice, namely I changed the supply voltage of LCD2004 from 5v (VBUS 40pin) to 3.3v(3V3(OUT) 36pin).

I'm not clear what the second picture is showing. Was that with it wired to I2C0?
--> Of course, it is wired to I2C0. SDA of LCD2004 is connected to GP16(I2C0 SDA 21pin) and SCL of LCD2004 is connected to GP17(I2C0 SCL 22pin). Souce code is below, which I called "Code for I2C0". I donot magic tricks. I attached the picture under above conditions.

// Code for I2C0 ---------------------------------------------------------
//SunFounder I2C LCD2004 (20x4 line) for I2C0 pin of pico W
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,20,4); // set the LCD address to 0x27

void setup()
{
// I2C pin set
Wire.setSDA(16); // 21pin(pico W): GP16 I2C0 SDA
Wire.setSCL(17); // 22pin(pico W): GP17 I2C0 SCL
Wire.begin();

lcd.init();

lcd.backlight();
}

void loop()
{
lcd.setCursor(0,0); //1st line
lcd.print ("Hellow World !!");
lcd.setCursor (0, 1); //2nd line
lcd.print ("How are you ?");
lcd.setCursor (0,2); //3rd line
lcd.print ("What is your name ?");
lcd.setCursor (0,3); //4th line
lcd.print ("How old are you ?");
}

[Andy2No]

Not bad. You may be able to get it working better on 3.3V by adjusting the contrast again.

So is I2C1 still not working? I notice there's a difference in initialisation using init() rather than begin(). You might do better by writing your own version of begin, e.g. begin2(TwoWire &i2c_bus) which just takes the wire object as a parameter but is otherwise the same.

For example, instead of this:

void LiquidCrystal_I2C::init(TwoWire &i2c_bus){
	_i2c_bus = i2c_bus;
	init_priv();
}

void LiquidCrystal_I2C::init_priv()
{
	_i2c_bus.begin();
	_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
	begin(_cols, _rows);  
}

Try just

void LiquidCrystal_I2C::begin2(TwoWire &i2c_bus){
	_i2c_bus = i2c_bus;
//	init_priv();
//void LiquidCrystal_I2C::init_priv()
	_i2c_bus.begin();
//	_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
	begin(_cols, _rows);  
}

or even just

void LiquidCrystal_I2C::begin2(TwoWire &i2c_bus){
	_i2c_bus = i2c_bus;
//	init_priv();
//void LiquidCrystal_I2C::init_priv()
//	_i2c_bus.begin();
//	_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
	begin(_cols, _rows);  
}

Failing that, look for anything else that's different when using Wire1 instead of Wire. Make sure it's always using _i2c_bus. to refer to the wire object, not Wire. There shouldn't be any reason for differences other than initialising the _i2c_bus variable before it's used. As it is, there are two main difference:

First:

	_i2c_bus.begin();

There shouldn't be any need for that if you just change your existing code to use

Wire1.begin();

lcd.init(Wire1);

Second:

	_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;

If using begin() works but init(Wire1) doesn't, perhaps this line is the main problem.

However, in your latest example, it seems you're using the original Wire library, not this one?

You're calling lcd.init() without a parameter, but the TwoWire parameter is not optional in this version. You have angled brackets ( < > ) in the path for the header file, so it's searching your libraries folder not taking the local version from your project folder (the same one with the .ino is in). In other words, you have:

#include <LiquidCrystal_I2C.h>

What you should have is

#include "LiquidCrystal_I2C.h"

So, first step, change that path and compile your I2C0 example again. What happens? I assume you get an error about the missing parameter. If you fix that, does it still work?

[YSDK001]

You may be able to get it working better on 3.3V by adjusting the contrast again.
---> I think so,namely turning the contrast potentiometer clockwise is better. But I cannot, because the rotation angle of the contrast has reached maximum angle.

So is I2C1 still not working?
---> Yes, at 3.3V, not a single character is displayed. Please see Picture1__None character at 3_3v Picture.jpg and Picture2__None character at 3_3v Code.jpg,which is the source code driving pico W of Picture1..
Below is IDE of source code. You can get the HellowWord_picoW.ino, LiquidCrystal_I2C.h and LiquidCrystal_I2C.h files by unzip HelloWorld_LiquidCrystal_I2C__002.zip file, which I sent a few days ago.

---

//YWROBOT
//Compatible with the Arduino IDE 1.0
//Library version:1.1
#include <Wire.h>

#include "LiquidCrystal_I2C.h"
//#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // Set the LCD address to 0x27 for a 16 chars and 2 line display

void setup()
{
//initialization of the lcd :
lcd.init(Wire1);

// I2C pin Setting
Wire1.setSDA(18); //pin24 (GP18 I2C1 SDA)
Wire1.setSCL(19); //pin25 (GP19 I2C1 SCL)
// Wire.begin();
// lcd.begin(Wire1);

// Turn on the blacklight and print a message.
lcd.backlight();
lcd.setCursor(3,0);
lcd.print("Hello, world!");
lcd.setCursor(2,1);
lcd.print("Ywrobot Arduino!");
lcd.setCursor(0,2);
lcd.print("Arduino LCM IIC 2004");
lcd.setCursor(2,3);
lcd.print("Power By Ec-yuan!");
}

void loop()
{
// Do nothing here...
}

Try just or or even just
---> I tried "Try just" and "even just" as your order. In both case I could compiled and wrote the firmware successfully. But I could not see any character of LCD2004, as same as Picture1__None character at 3_3v Picture.jpg. I attached these codes as HelloWorld_picoW_Try_Just.zip and HelloWorld_picoW_even_just.zip.
HelloWorld_picoW_Try_Just.zip
HelloWorld_picoW_even_just.zip

So, first step, change that path and compile your I2C0 example again. What happens? I assume you get an error about the missing parameter. If you fix that, does it still work?
--->

1. Without the change of "Try just" and "even just"
   I tried to compile below I2C0 which I called Code for I2C0, after I change the include file from #include <LiquidCrystal_I2C.h> to #include "LiquidCrystal_I2C.h", which is of cource for TwoWire &i2c_bus version without change of "Try just" and "even just" .
   I compiled successfully and wrote the firmware successfully. So I could see characters of LCD2004 below,
   1st line: Hellow World !!
   2ne line: How are you ?
   3rd line: What is your name ?
   4th line: How old are you ?
   I attached the pictures,
   Image1__Picture of LCD2004.jpg,Image1__the IDE of HelloWorld_picoW_I2C0_ino_jpg and Image1__IDE of LiquidCrystal_I2C_cpp_jpg. Also I attached HelloWorld_picoW_I2C0.zip.
   
   
   
   HelloWorld_picoW_I2C0.zip

2. "Try just"
   I changed LiquidCrystal_I2C.cpp and LiquidCrystal_I2C.h. as your order. I compiled successfully and wrote the firmware successfully. So I could see characters of LCD2004 , as same as above Image1__Picture of LCD2004.jpg.
   I attached the pictures,
   Image2__the IDE of HelloWorld_picoW_I2C0_Try_just_ino.jpg and Image2__IDE of LiquidCrystal_I2C_cpp.jpg and Image2__IDE of LiquidCrystal_I2C_h.jpg. Also I attached HelloWorld_picoW_I2C0_Try_just.zip.
   
   
   
   HelloWorld_picoW_I2C0_Try_just.zip

3. "even just"
   I changed LiquidCrystal_I2C.cpp and LiquidCrystal_I2C.h. as your order. I compiled successfully and wrote the firmware successfully. So I could see characters of LCD2004 , as same as above Image1__Picture of LCD2004.jpg.
   I attached the pictures,
   Image3__the IDE of HelloWorld_picoW_I2C0_even_just_ino.jpg and Image3__IDE of LiquidCrystal_I2C_cpp.jpg and Image3__IDE of LiquidCrystal_I2C_h.jpg. Also I attached HelloWorld_picoW_I2C0_even_just.zip.
   
   
   
   HelloWorld_picoW_I2C0_even_just.zip

[Andy2No]

Okay, so what happens when you change Wire to Wire1, and change the pins for
setSDA and setSCL?

Occasionally, a problem can be caused by bad soldering on a header pin. Since you have it on a breadboard, you could try other pairs of pins that are valid for I2C1 too. I can see six possible locations on the pinout:

[YSDK001]

Thank you very much for many excellent advice. Finally I could display characters on the LCD2004 via I2C1 of pico W.
Please see Picture1__Successful I2C1 test.JPG. This source, namely HelloWorld_picoW_Try_Just_updated.ino is below. LCD library files are the files in which I added your "Try_Just" order.

---

//YWROBOT
//Compatible with the Arduino IDE 1.0
//Library version:1.1
#include <Wire.h>
#include "LiquidCrystal_I2C.h"
//#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 4); //I changed this from "lcd(0x27, 16, 4)" to "lcd(0x27, 16, 2)".
//LiquidCrystal_I2C lcd(0x27, 16, 2); // Set the LCD address to 0x27 for a 16 chars and 2 line display

void setup()
{ //initialization of the lcd :
//lcd.begin2(Wire1);
//lcd.init(Wire1);

// I2C pin Setting
Wire1.setSDA(18); //pin24 (GP18 I2C1 SDA)
Wire1.setSCL(19); //pin25 (GP19 I2C1 SCL)
Wire1.begin(); //I changed this "// Wire.begin();" to "Wire1.begin();". Namely I removed comment out //.
//Wire.begin();
lcd.begin2(Wire1); //I changed this code set from " before Wire1.begin(); " to " after Wire1.begin();".
//lcd.begin(Wire1);
// Turn on the blacklight and print a message.
lcd.backlight();
lcd.setCursor(3,0);
lcd.print("Hello, world!");
lcd.setCursor(2,1);
lcd.print("Ywrobot Arduino!");
lcd.setCursor(0,2);
lcd.print("Arduino LCM IIC 2004");
lcd.setCursor(2,3);
lcd.print("Power By Ec-yuan!");
}
void loop()
{
// Do nothing here...
}

As you know, concerning LCD2004 the connections are below.
pin24(GP18 I2C1 SDA) of pico W ----> SDA of LCD2004
pin25(GP19 I2C1 SCL) of pico W ----> SCL of LCD2004

Today, Only in "ino" file, three changes were made.

1. LiquidCrystal_I2C lcd(0x27, 16, 4); //I changed this from "lcd(0x27, 16, 4)" to "lcd(0x27, 16, 2)".
   //LiquidCrystal_I2C lcd(0x27, 16, 2);

The above source code is created based on the sample below GitHub
johnrickman/LiquidCrystal_I2C#16
It seems sample source code LCD is 2 lines. But LCD2004 is 4 lines LCD.

2. Wire1.begin(); //I changed this "// Wire.begin();" to "Wire1.begin();". Namely I removed comment out //.
   //Wire.begin();

Last time, I made the mistake of deleting this part, namely Wire1.begin(); //Wire.begin();

3. lcd.begin2(Wire1); //I changed this code set from " before Wire1.begin(); " to " after Wire1.begin();".

Below is the setup()code of I2C0, which can display characters on LCD2004.

void setup()
{
// I2C0 pin set
Wire.setSDA(16); // 21pin(pico W): GP16 I2C0 SDA
Wire.setSCL(17); // 22pin(pico W): GP17 I2C0 SCL
Wire.begin();

lcd.init();
lcd.backlight();

I noticed that Wire.begin();(Wire1.begin();) and lcd.init();(lcd.begin2(Wire1);)were in a different order. I changed the order so I could see characters on LCD2004 Suddenly.
}

I attached IDE pictures of HelloWorld_picoW_Try_Just_updated.ino,LiquidCrystal_I2C.h and LiquidCrystal_I2C.cpp. Also I attached the zip.

Again thank you very much indeed for many excellent advice.



HelloWorld_picoW_Try_Just_updated.zip

[Andy2No]

You're welcome. I'm glad it's working for you.

[Andy2No]

Please mark this as the accepted answer, if it solved your original problem.

To summarise, the solution was to take an existing library that worked on I2C0, import the contents into your sketch and make changes to allow I2C1 to be used as an alternative.

This was simplified a bit by using a pull request for the library you were using which hadn't yet been accepted, but it needed a couple more changes:

... for the one you're using, there was a pull request to add support for Wire1, but it still hasn't been accepted:

johnrickman/LiquidCrystal_I2C#16

However, you could fork your own version and maybe merge that pull request, or you could just download the library and either install your own copy, then edit it, or just place the library files in your project folder, exit the IDE and then start it up again. Then change the include from #include <LiquidCrystal_I2C.h> to #include "LiquidCrystal_I2C.h" (quotes for a local path instead of angle brackets).

You can then edit the .h and .cpp files to get it to do what you want. Maybe add a pointer to the wire object to use to the class, and add an optional parameter to specify that, in the constructor, then look through the code for references to Wire and change them to use that pointer instead.

The rest of the details were discussed between us in the comments above.

[YSDK001]

Thank you very much for response.

Please mark this as the accepted answer, if it solved your original problem.
I clicked a button. I did your order. is this right?

Should I use this thread ?

[Andy2No]

The post I just made, with the summary, would have been better to mark as the answer but never mind.

I can't help with the Pico W question in the other thread because I don't own any. WiFi isn't really one of my interests.

[YSDK001]

I understand what you're saying. Thank you very much for all the advice you've given me so far.