Re: [lcd4linux] HD44780 I2C driver issue

[Benjamin F. <bfu...@go...>]

Hello Laurent,

did you have any success?



Am 10.04.2014 18:40, schrieb Michael Reinelt:
> Hello Laurent,
>
> Although I never owned nor used a HD44780-i2c-display, I had a quick look at the sources: i2c should support
> "Soft-Wiring", this menas you shouldbe able to specify the signals in lcd4linux.conf
>
> But I don't know the syntax :-) just try some of the examples from the normal wiring, usind onnly DB0..DB7
>
> try to strat lcd4linux with -fvv, ond look in the output for occurences like
>
> 	info("%s: wiring: [DISPLAY:%s]<==>[i2c:DB%d]", Driver, name, w);
>
> the soft-wiring code is in drv_generic_i2c.c, function
> unsigned char drv_generic_i2c_wire(const char *name, const char *deflt)
>
>
> good luck! :-)
>
>
> Am 2014-04-07 16:22, schrieb Laurent HAAS:
>> Hi all
>>
>> I'm currently trying to use lcd4linux on a WR703N router with OpenWRT,
>> with a 20x4 HD44780 LCD equipped with an I2C interface.
>>
>> Unfortunately, after several hours of struggle, I finally found that the
>> I2C integrated (soldered) interface -  model YwRobot LCM1602 - is
>> finally not compatible with the plain HD44780-I2C driver :-(  I got the
>> same behavior as the TRAC ticket #295 described.
>>
>> These LCD + interfaces are sold by many vendors (mostly Chinese etc.)
>> and under several brands.
>>
>> Actually, the 4 bits of data are assigned to the 4 HIGHER bits of the
>> "abstracted Port", and RS, RW, and EN are assigned to the LOWER bits :-(
>>
>> Here is the corresponding table between the PCF8574 output pins and the LCD
>>
>>       PCF 8574         LCD
>> Pin  Function   Pin  Function
>> 4      P0        4      RS
>> 5      P1        5      RW
>> 6      P2        6      EN
>> 7      P3        NC (backlight ?)
>> 9      P4        11     D4
>> 10     P5        12     D5
>> 11     P6        13     D6
>> 12     P7        14     D7
>>
>>    From what I read on the HD44780 wiki page, in 4 bits mode, the data
>> bits are ALWAYS assigned to DB0-DB3, and it seems there is no way to
>> assign them to DB4-DB7 (which in turn are always assigned to control
>> signals).
>>
>> Can you help ?
>>
>> Thanks !
>>
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>