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 ⟨https://github.com/jepler/odroid-linux/tree/odroid-3.8.13-rt⟩.

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