lcd4linux-devel

[Lcd4linux-devel] Driver & Questions: Futaba VFD M402SD06GL

[Marcus M. <cod...@gm...>]

Hello,

motivated and supported by Robert Resch I wrote a lcd4linux driver to
run a Futaba VFD M402SD06GL (bought mine in 2005, 40x2 chars) on the 
parallel port. The diff file is attached to this mail.

Due C is not my native language, I need a code review. 

At the moment the VFD shows no errors, but on the terminal the error
message...

unable to compact bar characters
nSegment=3 fSegment=2 CHARS=0 ICONS=0
Segment[0].val1=0 val2=0
Segment[1].val1=255 val2=255
Segment[2].val1=5 val2=1

... is shown (with variable values). What's to do?

Beside this I've some questions/concerns:

0. I'd like to install a switch on the 5V wire. By connecting the 5V
   with a status pin (using a 1-10kOhm resistor) I could check in the
   drivers write function if the VFD is switched off and ignore the
   commands in this case.
   But how can I get informed and rewrite all widgets when the VFD
   is switched on?

1. The driver name might be confusing because current Futaba VFDs seems
   to run with the HD44780 driver (as LCD emulators). 

2. The VFD supports no user defined chars or icons. So I made 
   drv_generic_text_real_defchar do nothing or should it point to NULL?

3. Char values below 0x20 are controll data (goto, reset, dim...). 
   Should they be filtered (or replaced by blanks) in the write function?

4. Do I have to add drv_generic_parport_hardwire_ctrl for D0-7?

5. What's the meaning of the first three arguments (val1,val2,dir) of 
   drv_generic_text_bar_add_segment and how must they to be 'constructed'?
   
6. Should I delete or comment out all the icon lines?


Thanks for your help.

Regards 

Marcus

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Re: [Lcd4linux-devel] Driver & Questions: Futaba VFD M402SD06GL

[Michael R. <mi...@re...>]

Hello Marcus,


> motivated and supported by Robert Resch I wrote a lcd4linux driver to
> run a Futaba VFD M402SD06GL (bought mine in 2005, 40x2 chars) on the
> parallel port. The diff file is attached to this mail.

Fine, thanks! I already committed your driver, so please du a 'svn up' before continueing...


> At the moment the VFD shows no errors, but on the terminal the error
> message...
>
> unable to compact bar characters
> nSegment=3 fSegment=2 CHARS=0 ICONS=0
> Segment[0].val1=0 val2=0
> Segment[1].val1=255 val2=255
> Segment[2].val1=5 val2=1
>
> ... is shown (with variable values). What's to do?

This is because yor display does not support user-defined characters. You have to disable bars and icons in this case.

> Beside this I've some questions/concerns:
>
> 0. I'd like to install a switch on the 5V wire. By connecting the 5V
>     with a status pin (using a 1-10kOhm resistor) I could check in the
>     drivers write function if the VFD is switched off and ignore the
>     commands in this case.
>     But how can I get informed and rewrite all widgets when the VFD
>     is switched on?

lcd4linux does not support this. restarting it (using SIGHUP) is the way to go.

> 1. The driver name might be confusing because current Futaba VFDs seems
>     to run with the HD44780 driver (as LCD emulators).
I see no problem here.

> 2. The VFD supports no user defined chars or icons. So I made
>     drv_generic_text_real_defchar do nothing or should it point to NULL?
set it to NULL

> 3. Char values below 0x20 are controll data (goto, reset, dim...).
>     Should they be filtered (or replaced by blanks) in the write function?
Yes, you could do so.

> 4. Do I have to add drv_generic_parport_hardwire_ctrl for D0-7?
no, because D0..D7 are data lines, the wiring stuff is for control lines only.

> 5. What's the meaning of the first three arguments (val1,val2,dir) of
>     drv_generic_text_bar_add_segment and how must they to be 'constructed'?
Have a look at the drv_WincorNixdorf.c, which is a text-mode driver with no support for user-defined characters. There 
is a "workaround" for such displays, they use a regular character to construct bars (a '*' in the case of WincorNixdorf)


> 6. Should I delete or comment out all the icon lines?
Yes, probably.


if you have further questions, just let me know!


regards, Michael

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