View Source Circuits.SPI.Bus protocol (circuits_spi v2.0.4)
A bus is the connection to a real or virtual SPI controller
Summary
Functions
Free up resources associated with the bus
Return the configuration for this SPI bus
Return the maximum transfer size in bytes
Transfer data
Types
@type t() :: term()
All the types that implement this protocol.
Functions
@spec close(t()) :: :ok
Free up resources associated with the bus
Well behaved backends free up their resources with the help of the Erlang garbage collector. However, it is good
practice for users to call Circuits.SPI.close/1
(and hence this function) so that
limited resources are freed before they're needed again.
@spec config(t()) :: {:ok, Circuits.SPI.spi_option_map()} | {:error, term()}
Return the configuration for this SPI bus
The configuration could be different that what was given to open/2
if
the device had to change it for it to work.
@spec max_transfer_size(t()) :: non_neg_integer()
Return the maximum transfer size in bytes
The number of bytes that can be sent and received at a time
may be capped by the low level SPI interface. For example,
the Linux spidev
driver allocates its transfer buffer at
initialization based on the bufsiz
parameter and rejects
requests that won't fit.
If you're sending large amounts of data over SPI, use this function to determine how to split up large messages.
Transfer data
Since each SPI transfer sends and receives simultaneously, the return value
will be a binary of the same length as data
.