[argyllcms] Re: Calibrating the DTP94

  • From: Oliver Schulz <whisp@xxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 22 Nov 2006 17:04:35 +0100

Hi,

> Hopefully, pin 12 provides enough current to power a MAX232 (but I'm
> afraid that 10mA may be not sufficient), and hopefully the voltage at
> pin 12 doesn't drop below 4.5V under load, (due to the diode, assuming
> that possibly Va = 5V, and not the voltage at pin 12), otherwise we're
> outside the required supply voltage range for the MAX232 (4.5...5.5V).

Should be sufficient, i think. If not, there's lot's of
low-power (and low voltage) variants of the MAX232 available,
some of which also require smaller capacitors, so one can use
0.1µF ceramics.

> Alternatively, it may be possible to interface the four signals to the
> parallel port (standard parallel port, not ECP or EPP) without needing
> any active components, but possibly just a pull-up resistor for "Data".

True, although parallel ports are dying out even faster than
serial ones. ;-)

> Another issue to consider is the availability of software interfaces
> provided by the OS to access the RS232 modem control lines or to access

This is not a problem (with ordinary user-level privileges),
every serial terminal program needs to use the handshake
lines, after all. Both Windows and Unix/Linux systems provide
API's for serial port access.
I'd guess that Graeme is quite familiar with them, since argyll
supports serial port devices. :-)
There's also a cross-platform Java library (rxtx) for seria
port access.


Regards,

Oliver

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