Use I2C/TWI LCD1602 Module with the propeller.
jtilghman
Posts: 67
I have the I2C/TWI LCD1602 Module from DFRobots. http://www.dfrobot.com/wiki/index.php?title=I2C/TWI_LCD1602_Module_(SKU:_DFR0063)
Sample code and the libraries are also at that link.
Its an 16x2 LCD with a I2C backpack on it. It works with the Arduino and it has libraries and they work in the arduino IDE.
I would like to make this with the propeller, but I think I am out of my depth here.
I am trying to learn SPIN and that's fun, but I am trying recode the libs for the LCD and trying to understand the I2C for the LCD. :depressed:
It's seems to be a little much.
If any one has some insight into making this work or would like to point me in the right direction, that would be great.
I thought I could just throw the correct codes down the I2C and that it might work.
Just a little help to get the LCD addressed and flash the backlight would be a great start.
Thanks,
John
Sample code and the libraries are also at that link.
Its an 16x2 LCD with a I2C backpack on it. It works with the Arduino and it has libraries and they work in the arduino IDE.
I would like to make this with the propeller, but I think I am out of my depth here.
I am trying to learn SPIN and that's fun, but I am trying recode the libs for the LCD and trying to understand the I2C for the LCD. :depressed:
It's seems to be a little much.
If any one has some insight into making this work or would like to point me in the right direction, that would be great.
I thought I could just throw the correct codes down the I2C and that it might work.
Just a little help to get the LCD addressed and flash the backlight would be a great start.
Thanks,
John
Comments
There are also several other versions out there, such as the very good one by Mike green: http://obex.parallax.com/objects/672/
What you really need to interface to that module is a datasheet. When doing I2C it's very important to have the register map: the series of addresses and functionality that define the operation of the module. After a quick inspection of the product page I couldn't find one. If you provide a link to the datasheet I could help more. If you can't find the data sheet, you'll have to go through the sample code provided and make your own register table. For example, using completely random values:
If you post your code we can provide more specific help.
One gotcha to be careful of is the I2C address: some drivers expect the address to be in the lower 7 bits, others expect it in the upper 7 bits. Some also expect you to provide the R/W lower bit.
Thanks for the reply. I have asked DFRobots for a datasheet or any more information that might be usable.
I also have access to the .h and the .cpp files for the arduino driver.
They can be seen here: https://dl.dropbox.com/u/12935294/I2CLCD/LiquidCrystal_I2C.h and https://dl.dropbox.com/u/12935294/I2CLCD/LiquidCrystal_I2C.cpp
In looking at the .h file, this part would make me think these are the device mappings you spoke about:
And maybe this is how its written down the I2C:
Anyway if this helps, let me know. I will keep digging to see what I can find.
As for code, my code isn't much more than some I2C objects and such but I can post it if you want to see.
I know I shouldn't be embarrassed about what my code looks like.
Thanks,
John
This is very likely the problem -- I ran into this while porting some I2C stuff from an Arduino project.
I think I am making some head way. I have taken code that JonnyMac wrote and have 'adapted' it. Its not complete and doesn't work. But its a start.
'' ================================================================================================= '' '' File....... LCD1602_demo.spin '' Purpose.... '' Author..... John Tilghman '' Copyright (c) 2012 John Tilghman '' -- see below for terms of use '' E-mail..... [EMAIL="john.tilghman@gmail.com"]john.tilghman@gmail.com[/EMAIL] '' Started.... 18 SEP 2012 '' Updated.... '' '' ================================================================================================= con _clkmode = xtal1 + pll16x _xinfreq = 5_000_000 ' use 5MHz crystal ' _xinfreq = 6_250_000 ' use 6.25MHz crystal CLK_FREQ = ((_clkmode - xtal1) >> 6) * _xinfreq MS_001 = CLK_FREQ / 1_000 US_001 = CLK_FREQ / 1_000_000 con RX1 = 31 ' programming / terminal TX1 = 30 SDL = 12 ' i2c / i2c SCA = 13 con LCD = $27 | (0 << 1) ' device address '' commands LCD_CLEARDISPLAY = $01 LCD_RETURNHOME = $02 LCD_ENTRYMODESET = $04 LCD_DISPLAYCONTROL = $08 LCD_CURSORSHIFT = $10 LCD_FUNCTIONSET = $20 LCD_SETCGRAMADDR = $40 LCD_SETDDRAMADDR = $80 '' flags for display entry mode LCD_ENTRYRIGHT = $00 LCD_ENTRYLEFT = $02 LCD_ENTRYSHIFTINCREMENT = $01 LCD_ENTRYSHIFTDECREMENT = $00 '' flags for display on/off control LCD_DISPLAYON = $04 LCD_DISPLAYOFF = $00 LCD_CURSORON = $02 LCD_CURSOROFF = $00 LCD_BLINKON = $01 LCD_BLINKOFF = $00 '' flags for display/cursor shift LCD_DISPLAYMOVE = $08 LCD_CURSORMOVE = $00 LCD_MOVERIGHT = $04 LCD_MOVELEFT = $00 '' flags for function set LCD_8BITMODE = $10 LCD_4BITMODE = $00 LCD_2LINE = $08 LCD_1LINE = $00 LCD_5x10DOTS = $04 LCD_5x8DOTS = $00 '' flags for backlight control LCD_BACKLIGHT = $08 LCD_NOBACKLIGHT = $00 En = 000100 '' Enable bit Rw = 000010 '' Read/Write bit Rs = 000001 '' Register select bit con #1, HOME, GOTOXY, #8, BKSP, TAB, LF, CLREOL, CLRDN, CR ' PST formmatting control #14, GOTOX, GOTOY, CLS obj term : "fullduplexserial64" ' for terminal i2c : "jm_i2c" ' i2c access var byte buffer[80] dat Menu byte "=======================", CR byte " i2c Demo ", CR byte "=======================", CR byte CR byte "[1] Backlight ON ", CR byte "[2] Backlight OFF ", CR byte 0 pub main | c term.start(RX1, TX1, 00, 115_200) ' start terminal I/O i2c.setup ' setup I2C buss (boot pins) repeat term.tx(CLS) term.str(@Menu) term.rxflush c := term.rx case c "1" : backlight_on "2" : backlight_off pub backlight_on term.tx(CLS) term.str(string("Turning Backlight ON !")) term.tx(CR) i2c.wr_strx(LCD, LCD_BACKLIGHT) press_key pub backlight_off term.tx(CLS) term.str(string("Turning Backlight ON !")) term.tx(CR) i2c.wr_strx(LCD, ADDR_LO, @TestStr1) ' write string press_key pub press_key term.str(string(CR, "Please press a key...")) term.rxflush term.rx pub pause(ms) | t '' Delay program in milliseconds if (ms < 1) ' delay must be > 0 return else t := cnt - 1792 ' sync with system counter repeat ms ' run delay waitcnt(t += MS_001) dat {{ Terms of Use: MIT License Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. }}The problem I think is that I don't understand completey whats going on. I have looked at the I2C specs and it says: send address, then data, but in the spin code it wants: id, address, value.
The C++ code I have from the arduino lib seems to only send address, data. I still have not figured out if its 7 or 8 bit but the arduino libs talk about 4 bit address. Also this device is a HD44780U with an I2C backpack on it.
Don't know if any of this helps.
Just trying to learn as I go and get something working..
Thanks,
JT