September-8th-2020, 03:14 PM
The communciation interface beetween a netX chip and the Host chip is SPI. Next to the 4 standard SPI signal a 5th signal is needed which is the chip select signal.
For example with netHAT module the pin 24 is used and hardwired to operate as chip select. If you now would operate two netHATs the same both modules would use pin 24 as chip select and hence both modules would get addressed by the Raspberry Pi CPU the same time which causes a conflict. What you would need are multiple netHAT modules that differ in the pinout and would user other free pins for the chip select. So there is no possibility since such modules no not exist. Or you build your own modules ...
The driver indeed has a parameter which SPI interface to use. You specify the Linux "/dev/spidevx.x." in a configuration file like "/dev/spidev0.1" or "/dev/spidev0.2" or "/dev/spidev0.3" etc. Today the driver just looks a single time to the single configuration file. There is no feature to get multiple driver instances running.
What exactly do you mean with CrossLink time? Do you mean the time to exchange POWERLINK data located the netX buffers with an application running on Linux? A customer measures the SPI overall performance and came to the result that it costs you 300us to 1.5ms until you have exchange the IO buffers from netX with a Linux application.
Thx
Armin
For example with netHAT module the pin 24 is used and hardwired to operate as chip select. If you now would operate two netHATs the same both modules would use pin 24 as chip select and hence both modules would get addressed by the Raspberry Pi CPU the same time which causes a conflict. What you would need are multiple netHAT modules that differ in the pinout and would user other free pins for the chip select. So there is no possibility since such modules no not exist. Or you build your own modules ...
The driver indeed has a parameter which SPI interface to use. You specify the Linux "/dev/spidevx.x." in a configuration file like "/dev/spidev0.1" or "/dev/spidev0.2" or "/dev/spidev0.3" etc. Today the driver just looks a single time to the single configuration file. There is no feature to get multiple driver instances running.
What exactly do you mean with CrossLink time? Do you mean the time to exchange POWERLINK data located the netX buffers with an application running on Linux? A customer measures the SPI overall performance and came to the result that it costs you 300us to 1.5ms until you have exchange the IO buffers from netX with a Linux application.
Thx
Armin
„You never fail until you stop trying.“, Albert Einstein (1879 - 1955)
