Re: [Lcd4linux-devel] display on WRAP-Board - how fast is i2c? ho w good is the lpc connector?

[Luis.F.Correia <Lui...@se...>]

Hi! 

I added back the list ;)

> -----Original Message-----
> From: Stefan Krister [mailto:ste...@cr...] 
> Sent: Tuesday, July 25, 2006 10:39 AM
> To: Luis.F.Correia
> Subject: Re: [Lcd4linux-devel] display on WRAP-Board - how 
> fast is i2c? ho w good is the lpc connector?
> 
> 
> Hi Luis,
> 
> Luis.F.Correia schrieb am 24.07.2006 15:41:
> > 
> > was this information usefull?
> 
> yes, a little ... are there 10kOhm resistors? And what for are they?

They are needed to pull up the I2C lines at 3.3V, this is a requirement from
the I2C specifications.

> I wired my display like yours. I configured lcd4linux as
> 
> Display DOG-16x3 {
>     Driver 'HD44780'
>     Model 'generic'
>     Bus 'i2c'
>     Device '64'
>     Port '/dev/i2c0'
>     Icons '8'
>     Size '16x3'
> 
>     Wire {
>         RW        'GND'
>         RS        'AUTOFD'
>         ENABLE    'STROBE'
>     }
> }
> 
> but I'm getting errors at start:
> 
> lcd4linux -f lcd4linux.conf -Fvv
> Version 0.10.1-CVS starting
> plugin_cfg.c: Variable halfminute = '30000' (30000)
> plugin_cfg.c: Variable minute = '60000' (60000)
> plugin_cfg.c: Variable tack = '100' (100)
> plugin_cfg.c: Variable tick = '500' (500)
> lcd4linux.c: initializing driver HD44780
> HD44780: $Revision: 1.62 $
> HD44780: using model 'generic'
> HD44780: using I2C bus
> HD44780: using 1 Controller(s)
> HD44780: using 4 bit mode
> udelay: CPU supports Time Stamp Counter
> udelay: CPU runs at 266.661000 MHz
> udelay: using TSC delay loop, 267 ticks per microsecond
> HD44780: initializing I2C bus /dev/i2c0
> device 64
> HD44780: I2C bus /dev/i2c0 open failed !
> 
> HD44780: could not initialize i2c attached device!
> HD44780: start display failed!
> 
> 
> Something with my i2c is going wrong ...
> 
> I'm using kernel 2.6.16.20 with loaded modules: i2c_core, 
> scx200_acb, lm77. Reading the WRAP temperature works fine 
> with this commandline:
> 
> sed 's/\([0-9]\{3\}\)$/.\1/' /sys/bus/i2c/devices/0-0048/temp1_input
> 
> but there is no other i2c-chip 'in sight' - I think, the i2c 
> core 'scans' the bus for chips?
> 
> And I don't have any /dev/i2c* files - I createt some, but 
> with no luck.

you'll need to add the specific /dev entries.

In WRAP, the temp sensor sits on bus 1, while the external bus is
bus 0. You are getting different results because you are using the 
in kernel I2C drivers. The WRAP board uses the 'worng' values for the
I2C AccessBus controllers. Please check in the driver I previously
sent to get the proper I/O ports. You may have to patch the I2C 
driver to match this board (scx200_acb i mean).

With lcd4linux, you will only need the i2c-core, i2c-dev, i2c-proc 
and the access bud driver.

Nothing else is needed, because we do RAW chip access.

> 
> I tried to load the pcf8574.ko module, which should print the 
> found chips - but nothing. The module loads but doesn't print 
> out anything.

This is useless, and if it won't find the chip is just because
the BUS assignments are wrong.

Can you post the dmesg messages?

> 
> MfG
> 
> Stefan
> 

Luis