paulwratt/spincl-bm2835

spincl is a command-line utility for executing spi commands with the Broadcom bcm2835.

Git Mirror of spicl from http://ipsolutionscorp.com/raspberry-pi-spi-utility/ As that site is currently down, posting the last clean version I have to github Open Source Licensing GNU GPLv3

DESCRIPTION

spincl is a command-line utility for executing spi commands with the Broadcom bcm2835. It was developed and tested on a Raspberry Pi single-board computer model B. The utility is based on the bcm2835 C library developed by Mike McCauley of Open System Consultants, http://www.open.com.au/mikem/bcm2835/.

Invoking spincl results in a full-duplex SPI transfer. Options include the the SPI clock frequency, SPI Mode, chip select designation, and chip select polarity. Invoking spincl requires root privilege. If no command-line arguments are included or if there are any command-line argument errors, a "usage statement" will be printed on stdout similar to below.

USAGE

spincl [options] len [xmit bytes]\n");

Invoking spincl results in a full-duplex SPI transfer of a specified number of bytes. Additionally, it can be used to set the appropriate GPIO pins to their respective SPI configurations or return them to GPIO input configuration. Options include the SPI clock frequency, SPI Mode, chip select designation, chip select polarity and an initialization option (spi_begin and spi_end). spincl must be invoked with root privileges.

The following are the options, which must be a single letter preceded by a '-' and followed by another character. -ix where x is the SPI init option, b[egin] or e[nd] The begin option must be executed before any transfer can happen It may be included with a transfer. The end option will return the SPI pins to GPIO inputs. It may be included with a transfer. -mx where x is the SPI mode, 0, 1, 2, or 3 -cx where x is the exponent of 2 of the clock divider. Allowed values are 0 through 15. Valid clock divider values are powers of 2. Corresponding frequencies are specified in bcm2835.h. -sx where x is 0 (CS0), 1 (CS1), 2 (CS1&CS2), or 3 (None) -px where x is chip select polarity, 0(LOW) or 1(HIGH)

len: The number of bytes to be transmitted and received (full duplex).

xmit bytes: The bytes to be transmitted if specified. If none are specified, 0s will be transmitted, which may be the case when only the received data is relevant.

EXAMPLES

Use spincl to just intialize the SPI pins spincl -ib

Use spincl to intialize the SPI pins and read three bytes (note xmit bytes are not specified). Mode is 2, clock frequency is 15.625Mhz (see bcm2835.h), chip select is 0, and polarity is active low. spincl -ib -m2 -c4 -s0 -p0 3

Use spincl to transmit 2 bytes (specified) and read back 2 bytes, which may or may not be relevant. Mode is 1, clock frequency is 7.8125MHz, chip select is 1, and polarity is active high. Note that no initialization has been specified so SPI pins must have been previously initialized. spincl -m1 -c5 -s1 -p1 2 0x5c 0x13

Use spincl to read two byte with mode 3, clock frequency of 15.625Mhz, and no chip select (done by user some other way). When the SPI tranfer has been completed, the SPI pins will be returned to GPIO inputs. spincl -ie -m3 -c4 -s3 2

Use spincl to just return the SPI pins to GPIO inputs spincl -ie

BUILD

The Makefile included assumes that the bcm2835 library has been installed. In other words, bcm2835.h is in /usr/local/include and libbcm2835.a is in /usr/local/lib. To "make" the executable, type make at the command-line prompt from the spincl directory. "make install" will intall spincl in /opt/aeris/bin/ and set the owner and group to root with the appropriate permissions.