hm2_spi - LinuxCNC HAL driver for the Mesa Electronics SPI Anything IO boards, with HostMot2 firmware.
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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.
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.
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.
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>.
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.
hostmot2(9)
GPL