Hi,

Today i'm trying to connect lcd 16x2 using i2c.
On router i have installed OpenWrt 12.09, and everything should be ok, but...
Device is recognized i set up correctly LCDd.config, but when i start server, the LCD is start blinking.

Of course between SDA i SCL i put 10k resistors to 3V3, and remove two 4,7k SMD resistors from PCB.
On router i connected to GPIO 7 and 29 - this point i found on R15 and R17 (I removed both resistors from PCB)

Is there anybody how have similar problem whit lcdproc?

Does i2cdetect from the package i2c-tools detect your device properly?

Yes, see:

root@OpenWrt:~# insmod i2c-gpio-custom bus0=0,7,29
root@OpenWrt:~# i2cdetect 0
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-0.
I will probe address range 0x03-0x77.
Continue? [Y/n] y
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3f
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
root@OpenWrt:~# dmesg | grep gpio
[    0.090000] gpiochip_add: registered GPIOs 0 to 29 on device: ath79
[   51.420000] i2c-gpio i2c-gpio.0: using pins 7 (SDA) and 29 (SCL)
root@OpenWrt:~# /etc/init.d/LCDd start

And there is some part of LCDd.conf:

## Hitachi HD44780 driver ##
[hd44780]

# Select what type of connection. See documentation for types.
ConnectionType=i2c

# Device of the serial interface [default: /dev/lcd]
Device=/dev/i2c-0
Port=0x3f


# Bitrate of the serial port (0 for interface default)
Speed=0

It's a bit strange, because LCD is only start blinking after start LCDd server...

It seems you have got the same problem as mentioned here: lines 1-4 and 5-8 of the I2C-adapter are swapped. So you can either apply this patch and build a new lcdproc package or rewire your display.

Thanks for replay.
So i should rewire D0-D3 to D4-D7? I have not enough skill to build packages, so options whit rewire is easiest for me

Yes, that is what I read there. Move all the 8 data lines by 4 lines: D0->D4, D1->D5, D2->D6, D3->D7, D4->D0, D5->D1, D6->D2, D7->D3.

So, i made this this modification - but there is still this same problem...
I have read that post, and now i change totally connection to LCD.

 * The connections are:
 * PCF8574AP  Bit    LCD
 * P0 (4)      0x01  D4 (11)
 * P1 (5)      0x02  D5 (12)
 * P2 (6)      0x04  D6 (13)
 * P3 (7)      0x08  D7 (14)
 * P4 (9)      0x10  RS (4)
 * P5 (10)      0x20  RW (5)
 * P6 (11)      0x40  EN (6)
 * P7 (12)      0x80  /backlight (optional, active-low)
 *

And add this part to LCDd.conf:

   i2c_line_RS=0x01
    i2c_line_RW=0x02
    i2c_line_EN=0x04
    i2c_line_BL=0x80
    i2c_line_D4=0x10
    i2c_line_D5=0x20
    i2c_line_D6=0x40
    i2c_line_D7=0x80
    Backlight=yes
    BacklightInvert=yes

And copy new hd44780.so file to /usr/lib/lcdproc, but now when i try to start server, i have this error:

root@OpenWrt:~# /etc/init.d/LCDd start
LCDd: '/usr/lib/lcdproc/hd44780.so' is not an ELF executable for MIPS
Could not open driver module /usr/lib/lcdproc/hd44780.so: File not found
Driver [hd44780] binding failed
Could not load driver hd44780
There is no output driver
Critical error while initializing, abort.

EDIT:

I'm absoluty sure, about connections - please see:

http://lcdproc.sourceforge.net/docs/sta … d44780-i2c

But now i have a question - how i need to change driver?

(Last edited by mcz on 8 Jan 2018, 19:57)

Well, at least you can not use the hd44780.so file, which is offered on that website. I don't know for what CPU type it was compiled, but it is very unlikely to be your type.
i2c_line_ options are also not supported in official lcdproc versions. You would need to compile a patched version using the OpenWrt toolchain. But I believe this is pretty off-topic for Hardware Hacking.

Uh, that sad...i checked that driver, and it's compiled for ARM...
Last question, in manual for lcdproc i found another way to connect lcd to device - 4bit - it is possible to connect lcd in this way to router using only GPIO without I2C? What do You think about that? I know manual is only for LPT, but i'm looking for solution

Of course - i can use lcd2usb - but it's very easy, and i used that in other project, so this is reason why i'm trying to use different  connection...