NAME
RPi::SPI - Communicate with devices over the Serial Peripheral Interface
(SPI) bus on Raspberry Pi
SYNOPSIS
# channel 0 and 1 are the hardware SPI pins
# CE0 and CE1
my $spi = RPi::SPI->new(0);
my $buf = [0x01, 0x02];
my $len = 2;
@$buf = $spi->rw($buf, $len);
# use a GPIO pin to expand the number of SPI
# channels. We'll bit-bang automatically. The
# GPIO pin must connect to the CS/SS pin on the
# IC you're using
$spi = RPi::SPI->new(26); # GPIO 26 is the CS
DESCRIPTION
This distribution provides you the ability to communicate with devices
attached to the channels on the Serial Peripheral Interface (SPI) bus.
Although it was designed for the Raspberry Pi, that's not a hard
requirement, and it should work on any Unix-type system that has support
for SPI.
You can use the hardware SPI pins CE0 and CE1 on the Raspberry Pi, but
if you need more SPI slaves, we'll also automatically bit-bang the SPI
bus using a standard GPIO pin for the Slave Select instead.
METHODS
new
Instantiates a new RPi::SPI instance, prepares a specific SPI bus
channel for use, then returns the object.
Parameters:
$channel
The SPI bus channel to initialize.
Mandatory: Integer, `0' for `/dev/spidev0.0' or `1' for
`/dev/spidev0.1'. You can also send in any number above `1'. If so,
we'll treat it as a GPIO pin (connected to the CS/SS pin of the IC), and
we'll bit-bang the CS automatically as to free up the onboard hardware
channels.
$speed
Optional, Integer. The data rate to communicate on the bus using.
Defaults to `1000000' (1MHz).
Dies if we can't open the SPI bus.
rw
Writes specified data to the bus on the channel specified in `new()',
then after completion, does a read of the bus and re-populates the write
buffer with the freshly read data, and returns it as an array.
Parameters:
$buf
Mandatory: Array reference where each element is an unsigned char
(0-255). This array is the write buffer; the data we'll be sending to
the SPI bus.
$len
Mandatory: Integer, the number of array elements in the `$buf' parameter
sent in above.
Return: The write buffer, after being re-populated with the read data,
as a Perl array reference.
Dies if we can't open the SPI bus.
AUTHOR
Steve Bertrand, `<steveb at cpan.org>'
LICENSE AND COPYRIGHT
Copyright 2017 Steve Bertrand.
This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.
See
http://dev.perl.org/licenses/ for more information.
