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The HiPi::Device::SPI module provides access to the kernel driver for the SPI bus.
See : SPI Device Driver
The settings for the SPI device can be controlled in the HiPi Control GUI.
The following interface modules use HiPi::Device::SPI as a backend and may contain code that helps with your own usage.
HiPi::Interface::MCP3008
HiPi::Interface::MCP49XX
Loads the kernel device driver modules for SPI spi_bcm2708 spidev When $forceunload is true, unloads the kernel modules first if they are loaded (effectively forces a reload) spidev is loaded with the current bufsiz Of course, the user the script is running as must have root permissions to load and unload kernel modules.
Unloads the kernel device driver modules for SPI spi_bcm2708 spidev Of course, the user the script is running as must have root permissions to load and unload kernel modules.
Returns the current bufsiz of a loaded spidev module. If the module is not loaded or the process does not have root permissions, returns the current default module setting for bufsiz.
Sets the bufsiz option of the spidev module. Must unload and load the kernel module to do this. Of course, the user the script is running as must have root permissions to load and unload kernel modules.
Returns an array containing the names of available devices. Will normally return ('/dev/spidev0.0', '/dev/spidev0.1')
Returns a new instance of the HiPi::Device::SPI class. You can optionally specify several parameters as key value pairs in the constructor. Their default values are: my $dev = HiPi::Device::SPI->new( devicename => '/dev/spidev0.0', speed => SPI_SPEED_MHZ_1, bitsperword => 8, delay => 0, ); In default setup mode the SPI driver for Raspberry Pi has two cable select pins assigned. For controlling a device connected to SPI0_CS0 you need devicename => '/dev/spidev0.0' For controlling a device connected to SPI0_CS1 you need devicename => '/dev/spidev0.1' You can control data transfer speed by specifying one of the following constants for the key value 'speed' SPI_SPEED_KHZ_500 SPI_SPEED_MHZ_1 SPI_SPEED_MHZ_2 SPI_SPEED_MHZ_4 SPI_SPEED_MHZ_8 SPI_SPEED_MHZ_16 SPI_SPEED_MHZ_32 You can import these constants into your namespace with: use HiPi::Device::SPI qw( :spi ); Consult SPI bus documentation if you find your devices need or would benefit from specifying none default values for 'bitsperword' and 'delay'. (I haven't discovered a use for these)
Writes $buffer to the connected SPI device and returns the length($buffer) bytes read. Uses the speed, bitsperword and delay settings specified in the constructor. Depending on your device you will probably have to pack / unpack the $buffer and return value and engage in some bit shifting to retrieve the returned value. Use the code for HiPi::Interface::MCP3008 as a simple guide.
$mode one of SPI_MODE_0 SPI_MODE_1 SPI_MODE_2 SPI_MODE_3 You can import these constants into your namespace with: use HiPi::Device::SPI qw( :spi ); The documentation for your SPI device should tell you which modes it supports. Default mode is SPI_MODE_0.
$speed one of SPI_SPEED_KHZ_500 SPI_SPEED_MHZ_1 SPI_SPEED_MHZ_2 SPI_SPEED_MHZ_4 SPI_SPEED_MHZ_8 SPI_SPEED_MHZ_16 SPI_SPEED_MHZ_32 You can import these constants into your namespace with: use HiPi::Device::SPI qw( :spi ); I have not yet investigated how this setting combines with the speed setting specified in the constructor. The commands are simply wrappers for the exposed kernel device driver calls.