Re: Questions around adding a monochrome graphics/ascii display driver over gpio framework

[Bill Blass <baringskiier%yahoo.com@localhost>]

Hello Iain,

Controlling via gpio(4) is a possibility I did not consider, and I do think it 
would be possible to use ioctl's to drive the parallel interface for this chip, 
yes.  I would, however, like to drive a wsdisplay so I will continue 
development on the hardware driver.

Not super familiar with the centronics port, but if appears do-able.  You'll 
probably want 12 wires (you may be able to get away with holding ChipSelect low 
and use 11 wires...not sure) to control the chip: 8 wires for data, then 4 
control lines (Enable/Reset/WR/ChipSelect).  

Thanks,
Bill



----- Original Message ----
From: Iain Hibbert <plunky%rya-online.net@localhost>
To: Bill Blass <baringskiier%yahoo.com@localhost>
Cc: tech-kern%NetBSD.org@localhost
Sent: Wednesday, October 1, 2008 10:22:52 AM
Subject: Re: Questions around adding a monochrome graphics/ascii display driver 
over gpio framework

On Tue, 30 Sep 2008, Bill Blass wrote:

> - The device for which my newly developed driver supports is a monochrome 
> CrystalFontz graphical and character display
> - The CrystalFontz display uses an internal EPSON s1d13700 chip to drive the 
> display

these look awesome, so much choice!

> 2) I do not intend to operate the display as a terminal.  I intend to
> operate the display as a status display which will contain a mix of
> ascii and bitmap images.  Ideally, I'd like to see a usermode
> appliation/service drive the display, but I am unsure how the usermode
> code will interfae with the driver.

just out of interest, since you are working with a userland application to
drive this and it is hooked to GPIO, can't you use ioctls on with gpio(4)
directly to drive it? (please bear in mind that I know nothing about it
but I would have thought a hardware driver would be more useful if you
wanted to drive a wsdisplay)

(btw the website says 8-bit parallel interface for this chip, can it be
hooked to a centronics port?)

iain