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.TH HM2_7I43 "9" "2008-05-13" "LinuxCNC Documentation" "HAL Component"
.de TQ
.br
.ns
.TP \\$1
..
.SH NAME
hm2_7i43 \- LinuxCNC HAL driver for the Mesa Electronics 7i43 EPP Anything IO board with HostMot2 firmware.
.SH SYNOPSIS
.HP
.B loadrt hm2_7i43 [ioaddr=\fIN\fB[,\fIN\fB...]] [ioaddr_hi=\fIN\fB[,\fIN\fB...]] [epp_wide=\fIN\fB[,\fIN\fB...]] [config=\fI"str[,str...]"\fB] [debug_epp=\fIN\fB[,\fIN\fB...]]
.RS 4
.TP
\fBioaddr\fR [default: 0x378]
The base address of the parallel port.
.TP
\fBioaddr_hi\fR [default: 0]
The secondary address of the parallel port, used to set EPP mode.
0 means to use ioaddr + 0x400.
.TP
\fBepp_wide\fR [default: 1]
Set to zero to disable the "wide EPP mode". "Wide" mode allows a 16-
and 32-bit EPP transfers, which can reduce the time spent in the read
and write functions. However, this may not work on all EPP parallel
ports.
.TP
\fBconfig\fR [default: ""]
HostMot2 config strings, described in the hostmot2(9) manpage.
.TP
\fBdebug_epp\fR [default: 0]
Developer/debug use only! Enable debug logging of most EPP
transfers.
.RE
.SH DESCRIPTION
hm2_7i43 is a device driver that interfaces the Mesa 7i43 board with
the HostMot2 firmware to the LinuxCNC HAL. Both the 200K and the 400K
FPGAs are supported.
The driver talks with the 7i43 over the parallel port, not over USB. USB
can be used to power the 7i43, but not to talk to it. USB communication
with the 7i43 will not be supported any time soon, since USB has poor
real-time qualities.
The driver programs the board's FPGA with firmware when it registers
the board with the hostmot2 driver. The old bfload(1) firmware loading
method is not used anymore. Instead the firmware to load is specified
in the \fBconfig\fR modparam, as described in the hostmot2(9) manpage,
in the \fIconfig modparam\fR section.
Some parallel ports require special initialization before they can be
used. LinuxCNC provides a kernel driver that does this initialization
called probe_parport. Load this driver before loading hm2_7i43, by
putting "loadrt probe_parport" in your .hal file.
.SH Jumper settings
To send the FPGA configuration from the PC, the board must be configured
to get its firmware from the EPP port. To do this, jumpers W4 and W5
must both be down, ie toward the USB connector.
The board must be configured to power on whether or not the USB interface
is active. This is done by setting jumper W7 up, ie away from the edge
of the board.
.SH Communicating with the board
The 7i43 communicates with the LinuxCNC computer over EPP, the Enhanced
Parallel Port. This provides about 1 MBps of throughput, and the
communication latency is very predictable and reasonably low.
The parallel port must support EPP 1.7 or EPP 1.9. EPP 1.9 is prefered,
but EPP 1.7 will work too. The EPP mode of the parallel port is sometimes
a setting in the BIOS.
Note that the popular "NetMOS" aka "MosChip 9805" PCI parport cards \fBdo
not work\fR. They do not meet the EPP spec, and cannot be reliably used
with the 7i43. You have to find another card, sorry.
EPP is very reliable under normal circumstances, but bad cabling
or excessively long cabling runs may cause communication timeouts.
The driver exports a parameter named hm2_7i43.<BoardNum>.io_error to
inform HAL of this condition. When the driver detects an EPP timeout,
it sets io_error to True and stops communicating with the 7i43 board.
Setting io_error back to False makes the driver start trying to
communicate with the 7i43 again.
Access to the EPP bus is not threadsafe: only one realtime thread may
access the EPP bus.
.SH SEE ALSO
hostmot2(9)
.SH LICENSE
GPL
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