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bzijlstra
Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands
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 Posted: Tue Sep 02, 2014 7:21 pm Post subject: Arduino Nano with I2c LCD and backlight |
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Bought a small piece of hardware. It is a I2c module for a LCD-display.
It can be connected to a display like this
And I found in the application note AN #118 a way to display text on this display via I2c.
But got some problems with the backlight.
Made a small addition to the library of Kent, renamed lcd_i2c.lib into bl_lcd_i2c.lib
And with this code backlight can be put on or off.
| Code: | 'I2c LCD on Arduino Nano 16x2 display with backlight
$regfile = "M328pdef.dat" ' the used chip
$crystal = 16000000 ' frequency used
$baud = 9600 ' baud rate
Declare Sub I2c_scan
Config I2cdelay = 10
$lib "i2c_twi.lib" 'hardware i2c/TWI
Config Twi = 100000
$lib "bl_Lcd_i2c.lib" ' AN #118 library from Kent
' with this addition
' * lds r27,{backlight}
' andi _temp2,&hf7
' or _temp2,r27
'LCD-display including backlight
'0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1
'1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
'G 5 C R R E D D D D D D D D B B
'N O S W 0 1 2 3 4 5 6 7 L L
'D V N S
'PCF8574
'P7 = D7
'P6 = D6
'P5 = D5
'P4 = D4
'P3 = 1 = backlight on / 0 = backlight off
'P2 = E
'P1 = RW
'P0 = RS
Const Pcf_d4 = 4
Const Pcf_d5 = 5
Const Pcf_d6 = 6
Const Pcf_d7 = 7
Const Pcf_rs = 0
Const Pcf_rw = 1
Const Pcf_e1 = 2
Dim B As Byte
Dim A As Byte
Dim _lcd_e As Byte
Dim Backlight As Byte
Backlight_on Alias &H08
Backlight_off Alias &H00
Backlight = Backlight_on
_lcd_e = 128
Const Pcf8574_lcd = &H4E 'Defines the address of the I/O expander for LCD
Config Scl = Portc.5 'we need to provide the SCL pin name
Config Sda = Portc.4
I2cinit
'Call I2c_scan 'if you want to check if the PCF8574 is seen activate this
Wait 2
cls
home
Lcd "i2c-display" 'display this at the top line
Wait 1
Lowerline 'select the lower line
Wait 1
Lcd "Shift this." 'display this at the lower line
Wait 1
For A = 1 To 10
Shiftlcd Right 'shift the text to the right
Waitms 250 'wait a moment
Next
For A = 1 To 10
Shiftlcd Left 'shift the text to the left
Waitms 250 'wait a moment
Next
Locate 2 , 1 'set cursor position
Lcd "*" 'display this
Wait 1 'wait a moment
Shiftcursor Right 'shift the cursor
Lcd "@" 'display this
Wait 1 'wait a moment
Home Upper 'select line 1 and return home
Lcd "Replaced." 'replace the text
Wait 1 'wait a moment
Cursor Off Noblink 'hide cursor
Wait 1 'wait a moment
Cursor On Blink 'show cursor
Wait 1 'wait a moment
Display Off 'turn display off
Wait 1 'wait a moment
Display On 'turn display on
'Now lets build a special character
'the first number is the characternumber (0-7)
'The other numbers are the rowvalues
'Use the LCD tool to insert this line
Deflcdchar 2 , 32 , 10 , 32 , 14 , 17 , 17 , 17 , 14 ' replace ? with number (0-7)
Deflcdchar 0 , 32 , 4 , 32 , 14 , 18 , 18 , 18 , 13 ' replace ? with number (0-7)
Deflcdchar 1 , 32 , 10 , 32 , 14 , 18 , 18 , 18 , 13 ' replace ? with number (0-7)
_lcd_e = 128
Cls 'select data RAM
Rem it is important that a CLS is following the deflcdchar statements because it will set the controller back in datamode
Lcd Chr(0) ; Chr(1) 'print the special character
'----------------- Now use an internal routine ------------
_temp1 = 2 'value into ACC
!rCall _write_lcd 'put it on LCD
'**************************************************************************
End
Sub I2c_scan ' check all devices on the I2c-bus
Print "Scan start"
For B = 0 To 254 Step 2 'for all odd addresses
I2cstart 'send start
I2cwbyte B 'send address
If Err = 0 Then 'we got an ack
Print "Slave at : " ; B ; " hex : " ; Hex(b) ; " bin : " ; Bin(b)
End If
I2cstop 'free bus
Next
Print "End Scan"
End Sub
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You can use this code to scan the I2c bus to find your I2c_LCD module. I have found it on address &H4E
On the Arduino Nano I have used the hardware I2c
In the code you will find the small addition I have made to get the backlight working. I found this small piece of code in the German Bascom-forum.
And here the module, a LCD working on a breadboard.
Have fun
Ben Zijlstra |
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albertsm
Joined: 09 Apr 2004
Posts: 4919
Location: Holland
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| Posted: Tue Sep 02, 2014 10:06 pm Post subject: |
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Thanks for sharing Ben, well done.
Amazing what you can buy. A good solution when having not enough pins for an LCD.
_________________
Mark |
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sasha_1973
Joined: 30 Jul 2013
Posts: 58
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| Posted: Mon Mar 02, 2015 2:27 am Post subject: |
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Good health!
Does not work?
Can tell me, what's the problem? |
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maxneo
Joined: 07 Sep 2010
Posts: 35
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| Posted: Sat Jul 04, 2015 1:56 pm Post subject: 4x20 lcd |
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This lib does not work for 4x20 display is the one that has the lib for it?
Sincerely |
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bzijlstra
Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands
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Yenary
Joined: 19 May 2009
Posts: 3
Location: Yogyakarta
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| Posted: Tue Sep 29, 2015 10:00 am Post subject: Re: Arduino Nano with I2c LCD and backlight |
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| bzijlstra wrote: | Bought a small piece of hardware. It is a I2c module for a LCD-display.
It can be connected to a display like this
And I found in the application note AN #118 a way to display text on this display via I2c.
But got some problems with the backlight.
Made a small addition to the library of Kent, renamed lcd_i2c.lib into bl_lcd_i2c.lib
And with this code backlight can be put on or off.
| Code: | 'I2c LCD on Arduino Nano 16x2 display with backlight
$regfile = "M328pdef.dat" ' the used chip
$crystal = 16000000 ' frequency used
$baud = 9600 ' baud rate
Declare Sub I2c_scan
Config I2cdelay = 10
$lib "i2c_twi.lib" 'hardware i2c/TWI
Config Twi = 100000
$lib "bl_Lcd_i2c.lib" ' AN #118 library from Kent
' with this addition
' * lds r27,{backlight}
' andi _temp2,&hf7
' or _temp2,r27
'LCD-display including backlight
'0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1
'1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
'G 5 C R R E D D D D D D D D B B
'N O S W 0 1 2 3 4 5 6 7 L L
'D V N S
'PCF8574
'P7 = D7
'P6 = D6
'P5 = D5
'P4 = D4
'P3 = 1 = backlight on / 0 = backlight off
'P2 = E
'P1 = RW
'P0 = RS
Const Pcf_d4 = 4
Const Pcf_d5 = 5
Const Pcf_d6 = 6
Const Pcf_d7 = 7
Const Pcf_rs = 0
Const Pcf_rw = 1
Const Pcf_e1 = 2
Dim B As Byte
Dim A As Byte
Dim _lcd_e As Byte
Dim Backlight As Byte
Backlight_on Alias &H08
Backlight_off Alias &H00
Backlight = Backlight_on
_lcd_e = 128
Const Pcf8574_lcd = &H4E 'Defines the address of the I/O expander for LCD
Config Scl = Portc.5 'we need to provide the SCL pin name
Config Sda = Portc.4
I2cinit
'Call I2c_scan 'if you want to check if the PCF8574 is seen activate this
Wait 2
cls
home
Lcd "i2c-display" 'display this at the top line
Wait 1
Lowerline 'select the lower line
Wait 1
Lcd "Shift this." 'display this at the lower line
Wait 1
For A = 1 To 10
Shiftlcd Right 'shift the text to the right
Waitms 250 'wait a moment
Next
For A = 1 To 10
Shiftlcd Left 'shift the text to the left
Waitms 250 'wait a moment
Next
Locate 2 , 1 'set cursor position
Lcd "*" 'display this
Wait 1 'wait a moment
Shiftcursor Right 'shift the cursor
Lcd "@" 'display this
Wait 1 'wait a moment
Home Upper 'select line 1 and return home
Lcd "Replaced." 'replace the text
Wait 1 'wait a moment
Cursor Off Noblink 'hide cursor
Wait 1 'wait a moment
Cursor On Blink 'show cursor
Wait 1 'wait a moment
Display Off 'turn display off
Wait 1 'wait a moment
Display On 'turn display on
'Now lets build a special character
'the first number is the characternumber (0-7)
'The other numbers are the rowvalues
'Use the LCD tool to insert this line
Deflcdchar 2 , 32 , 10 , 32 , 14 , 17 , 17 , 17 , 14 ' replace ? with number (0-7)
Deflcdchar 0 , 32 , 4 , 32 , 14 , 18 , 18 , 18 , 13 ' replace ? with number (0-7)
Deflcdchar 1 , 32 , 10 , 32 , 14 , 18 , 18 , 18 , 13 ' replace ? with number (0-7)
_lcd_e = 128
Cls 'select data RAM
Rem it is important that a CLS is following the deflcdchar statements because it will set the controller back in datamode
Lcd Chr(0) ; Chr(1) 'print the special character
'----------------- Now use an internal routine ------------
_temp1 = 2 'value into ACC
!rCall _write_lcd 'put it on LCD
'**************************************************************************
End
Sub I2c_scan ' check all devices on the I2c-bus
Print "Scan start"
For B = 0 To 254 Step 2 'for all odd addresses
I2cstart 'send start
I2cwbyte B 'send address
If Err = 0 Then 'we got an ack
Print "Slave at : " ; B ; " hex : " ; Hex(b) ; " bin : " ; Bin(b)
End If
I2cstop 'free bus
Next
Print "End Scan"
End Sub
|
You can use this code to scan the I2c bus to find your I2c_LCD module. I have found it on address &H4E
On the Arduino Nano I have used the hardware I2c
In the code you will find the small addition I have made to get the backlight working. I found this small piece of code in the German Bascom-forum.
And here the module, a LCD working on a breadboard.
Have fun
Ben Zijlstra |
Thank very much. Very helpfull. my problem solved.
_________________
Stephen Mahago |
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yamaja
Joined: 27 Sep 2015
Posts: 3
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| Posted: Sun Oct 18, 2015 8:33 am Post subject: successfully first device, but trouble in the second devices |
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Hi Ben. nice to meet you. really thanks for your awesome sharing.
by the way, we have successfully run the text using i2c lcd 16x2, an atmega 16
but when we try to use for the second devices, it seem something troubling us. the lcd did not show any text, only a blinking cursor. keep running. the micro can communicate to the lcd to close down the light.
we have try 3 (three) different module, the result is same, it can not show the text.
we have attach the video to show the result.
could you tell us how to fix this problem ?
Thanks ben,
--------------------------------------------------
after several days troubleshooting, we found that the problem lies in the lcd. we have bought 10 lcd, only 1 work normally:cry: , . after using other brand of 16 x 2 lcd", our problem solved. temporary our solution is changes the lcd. i wonder if there is any other solution.
we will share our lcd 16 x 2 picture that do not work, hope other member that met this problem can be useful. thanks for this great forum  |
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bzijlstra
Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands
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| Posted: Thu Oct 29, 2015 12:15 pm Post subject: delays and pull-ups... |
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I must have missed your question, now I have seen you got some trouble with the adapted library.
Perhaps you have got a timing problem. Perhaps you can go over the library and add some NOP's, specially when writing commands en data to the display.
And you could check if you got pull-ups on your I2c-adapter. There should be 10 K ohm resistors to VCC on both SDA and SCL.
Have fun
Ben Zijlstra |
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yamaja
Joined: 27 Sep 2015
Posts: 3
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| Posted: Fri Oct 30, 2015 5:36 am Post subject: |
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thanks ben. you are such a great person
love this forum. Go !!!! |
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digibert
Joined: 03 Dec 2005
Posts: 1
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| Posted: Thu Mar 10, 2016 5:46 pm Post subject: |
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Hi Ben,
i have bought at banggood three LCD 1602-modules with exact the same I2C-Adaptors mounted already.
I have tried now several examples found in internet to drive them with BASCOM, without any success. (my mc also is a "arduino nano")
I found now your solution and tried it, with one step forward but have the same effect as "Yamaja":
I can swich the backlight On/Off without problem, but when sending text to LCD i get only one blinking cursur for a moment.
(means my I2C-Adress found with hex7E is ok and the pin-layout must be the same as yours)
i do not understand how to modify your lib with nops, may i ask to tell me more please ?
(my pull-up resistors on SDA and SCL are ok) |
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Paulvk
Joined: 28 Jul 2006
Posts: 1159
Location: SYDNEY
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| Posted: Wed Jun 15, 2016 1:40 pm Post subject: |
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Ben
I have been having trouble with this sometimes it worked then not.
Well I found it if I do not start with "home" I get problems
Regards Paul |
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bzijlstra
Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands
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| Posted: Wed Jun 15, 2016 2:27 pm Post subject: Home sweet home... |
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Paul
Thanks for your reply. So home should be used.
Have fun
Ben Zijlstra |
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Paulvk
Joined: 28 Jul 2006
Posts: 1159
Location: SYDNEY
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| Posted: Thu Jun 16, 2016 9:59 am Post subject: |
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Here is a short program that when the "Home" is removed puts random text on LCD
Regards Paul
| Code: |
$regfile = "m328pdef.dat"
$crystal = 16000000
$baud = 57600
$hwstack = 100 ' default use 32 for the hardware stack
$swstack = 100 'default use 10 for the SW stack
$framesize = 100 'default use 40 for the frame space
Config I2cdelay = 40
$lib "i2c_twi.lib" 'hardware i2c/TWI
Config Twi = 100000
$lib "bl_Lcd_i2c.lib" ' AN #118 library from Kent
Backlight_on Alias &H08
Backlight_off Alias &H00
Const Pcf_d4 = 4
Const Pcf_d5 = 5
Const Pcf_d6 = 6
Const Pcf_d7 = 7
Const Pcf_rs = 0
Const Pcf_rw = 1
Const Pcf_e1 = 2
Dim B As Byte
Dim A As Byte
Dim _lcd_e As Byte
Dim Backlight As Byte
_lcd_e = 128
Const Pcf8574_lcd = &H4E 'Defines the address of the I/O expander for LCD
Config Scl = Portc.5 'we need to provide the SCL pin name
Config Sda = Portc.4
'=======================================
'without this you get rubbish on LCD at power up
Home
'=======================================
Locate 1 , 1
Lcd "Test Line 1"
Locate 2 , 1
Lcd "Test Line 2"
End
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Paulvk
Joined: 28 Jul 2006
Posts: 1159
Location: SYDNEY
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| Posted: Fri Jun 17, 2016 12:38 pm Post subject: |
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Looking at this library I thought why is the address a constant
why is it not a variable
For my first stab at ASM
so I made it one
and it worked!!
But I only have one I2C Lcd module
so I changed the address of the module with the jumper on the back to &H46
Then dimension a variable Pcf8574_loc as byte
then Pcf8574_loc = &H46
So why do this?
We can now have multiple LCDs it is a bus after all !
Ben if you have more than one could you test it!
Regards Paul |
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bzijlstra
Joined: 30 Dec 2004
Posts: 1179
Location: Tilburg - Netherlands
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| Posted: Fri Jun 17, 2016 2:05 pm Post subject: Will do a test with several I2c LCDs |
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Thanks Paul
Will do a test with more than one I2c LCD.
And publish the result
Have fun
Ben Zijlstra |
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