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<table class="head">
<tr>
<td class="head-ltitle">PBIO(4)</td>
<td class="head-vol">Device Drivers Manual (i386)</td>
<td class="head-rtitle">PBIO(4)</td>
</tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">pbio</code> — <span class="Nd">8255
parallel peripheral interface basic I/O driver</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="Cd">device pbio</code></p>
<p class="Pp">In <span class="Pa">/boot/device.hints</span>:
<br/>
<code class="Cd">hint.pbio.0.at="isa"</code>
<br/>
<code class="Cd">hint.pbio.0.port="0x360"</code></p>
<p class="Pp">
<br/>
<code class="In">#include
<<a class="In">dev/pbio/pbioio.h</a>></code></p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">pbio</code> driver supports direct access to
the Intel 8255A programmable peripheral interface (PPI) chip running in mode
0 (simple I/O). Such an interface provides 24 digital I/O lines. The driver
is designed for performing I/O under program control using peripherals such
as the Advantech PCL-724 card, which emulates the Intel 8255A PPI in mode 0.
Other 8255A-based peripherals such as the BMC Messsysteme PIO24II card have
also been reported to work.</p>
<p class="Pp">The PPI provides two 8-bit ports (port A and port B) and two 4-bit
ports (port C upper, port C lower). Each port can be individually programmed
for input and (latched) output, and appears at a different offset of the
device's base I/O address.</p>
<p class="Pp">A separate register allows the configuration of ports for input or
output. The device is so simple, that reliably probing for it when input
data arrives at its terminals is impossible; therefore the kernel
configuration has to specify the device's base address. The device driver
provides four character devices that correspond to the peripheral's I/O
ports. Opening a device for read or write automatically configures the
corresponding hardware port for input or output. At boot time all ports are
set configured for input to avoid damaging external circuitry.</p>
<p class="Pp">A set of <a class="Xr">ioctl(2)</a> requests allow polled input
and paced output to be efficiently performed at the driver level without
expensive user/kernel context switching. The driver can perform I/O in three
different ways:</p>
<dl class="Bl-tag">
<dt>Basic</dt>
<dd>The read or write operation returns immediately after reading or writing
the data to the port at bus speed.</dd>
<dt>Paced</dt>
<dd>Data is transferred from or to the port at intervals specified by a
separate <a class="Xr">ioctl(2)</a> call.</dd>
<dt>Differential</dt>
<dd>(Input only.) Only port values that differ from the previous port value
are returned.</dd>
</dl>
<p class="Pp" id="Hz">The pacing interval is specified in
<a class="permalink" href="#Hz"><i class="Em">Hz</i></a> unit increments.
Setting a pace of <var class="Ar">n</var> seconds will result in no more
than one value being read or written every <var class="Ar">n</var> seconds.
Single byte read/write operations will take at least <var class="Ar">n</var>
seconds to complete.</p>
<p class="Pp">The following <a class="Xr">ioctl(2)</a> calls are supported:</p>
<dl class="Bl-tag">
<dt id="PBIO_SETDIFF"><a class="permalink" href="#PBIO_SETDIFF"><code class="Dv">PBIO_SETDIFF</code></a></dt>
<dd>accepts a pointer to an integer as the third argument, and sets the driver
for differential input if the integer is non-zero. The input pace speed
determines the periodic interval the driver will use to examine the port
for a changed value.</dd>
<dt id="PBIO_GETDIFF"><a class="permalink" href="#PBIO_GETDIFF"><code class="Dv">PBIO_GETDIFF</code></a></dt>
<dd>accepts a pointer to an integer as the third argument, and sets the
integer to the last set value for differential input.</dd>
<dt id="PBIO_SETIPACE"><a class="permalink" href="#PBIO_SETIPACE"><code class="Dv">PBIO_SETIPACE</code></a></dt>
<dd>accepts a pointer to an integer as the third argument, and sets the
driver's input pacing speed to the value of that integer.</dd>
<dt id="PBIO_GETIPACE"><a class="permalink" href="#PBIO_GETIPACE"><code class="Dv">PBIO_GETIPACE</code></a></dt>
<dd>accepts a pointer to an integer as the third argument, and sets the
integer to the last set value for the input pace.</dd>
<dt id="PBIO_SETOPACE"><a class="permalink" href="#PBIO_SETOPACE"><code class="Dv">PBIO_SETOPACE</code></a></dt>
<dd>accepts a pointer to an integer as the third argument, and sets the
driver's output pacing speed to the value of that integer.</dd>
<dt id="PBIO_GETOPACE"><a class="permalink" href="#PBIO_GETOPACE"><code class="Dv">PBIO_GETOPACE</code></a></dt>
<dd>accepts a pointer to an integer as the third argument, and sets the
integer to the last set value for the output pace.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="FILES"><a class="permalink" href="#FILES">FILES</a></h1>
<dl class="Bl-tag Bl-compact">
<dt><span class="Pa">/dev/pbio0a</span></dt>
<dd>Port A (8 bit I/O).</dd>
<dt><span class="Pa">/dev/pbio0b</span></dt>
<dd>Port B (8 bit I/O).</dd>
<dt><span class="Pa">/dev/pbio0ch</span></dt>
<dd>Port C upper (4 bit I/O).</dd>
<dt><span class="Pa">/dev/pbio0cl</span></dt>
<dd>Port C lower (4 bit I/O).</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
ALSO</a></h1>
<p class="Pp"><cite class="Rs"><span class="RsA">Diomidis Spinellis</span>,
<span class="RsT">The information furnace: Consolidated home control</span>,
<i class="RsJ">Personal and Ubiquitous Computing</i>,
<span class="RsN">1</span>, <span class="RsV">7</span>,
<span class="RsP">53-69</span>, <span class="RsD">2003</span>.</cite></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The <code class="Nm">pbio</code> device was first used under
<span class="Ux">FreeBSD 4.1</span>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
<p class="Pp"><span class="An">Diomidis D. Spinellis</span>
<<a class="Mt" href="mailto:dds@aueb.gr">dds@aueb.gr</a>></p>
</section>
<section class="Sh">
<h1 class="Sh" id="BUGS"><a class="permalink" href="#BUGS">BUGS</a></h1>
<p class="Pp">One of the PCL-724 card's inputs can optionally be wired to
generate an interrupt. This feature is not supported.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">January 14, 2005</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
