NAME

       hm2_spi - LinuxCNC HAL driver for the Mesa Electronics SPI Anything IO boards, with HostMot2 firmware.

SYNOPSIS

       loadrt hm2_spi [config="str[,str...]"] [spidev_path=path[,path...]] [spidev_rate=rate[,rate...]]

           config [default: ""]
                  HostMot2 config strings, described in the hostmot2(9) manpage.

           spidev_path [default: "/dev/spidev1.0"]
                  The path to the spi device node, a character special device in /dev

           spidev_rate [default: 24000]
                  The  desired  rate  of the SPI clock in kHz.  If the exact specified clock is not available, a
                  lower clock is used.  Due to shortcomings in the spidev API, it is not  possible  for  hal  to
                  report the actual clock used.

DESCRIPTION

       hm2_spi  is  a  device  driver  that  interfaces  Mesa's SPI based Anything I/O boards (with the HostMot2
       firmware) to the LinuxCNC HAL.

       The supported boards are: 7I90HD.

       The board must have a compatible firmware loaded on the board by the mesaflash(1) program.

       hm2_spi is only available when LinuxCNC is configured with "uspace" realtime.

INTERFACE CONFIGURATION

       It is possible for one SPI bus to connect several devices; in this configuration,  a  master  device  has
       several  chip  select lines.  In order to meet realtime deadlines,  hm2_spi should be used on a dedicated
       SPI interface not shared with any other slaves.

REALTIME PERFORMANCE OF LINUX SPIDEV DRIVERS

       As of kernel 3.8, most or all kernel SPI drivers do not achieve the high realtime response rate  required
       for  a  typical LinuxCNC configuration.  The driver was tested with a modified version of the spi-s3c64xx
       SPI driver on the Odroid U3 platform.  The patched kernel resides on github.

SPI CLOCK RATES

       The maximum SPI clock of the 7i90 is documented as 50MHz.  Other elements of the data  path  between  HAL
       and the 7i90 may impose other limitations.

SEE ALSO

       hostmot2(9)

LICENSE

       GPL

LinuxCNC Documentation                             2008-05-13                                         HM2_SPI(9)