- Generated by
1.8.13
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Robot Control Library
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General purpose C interface to the Linux SPI driver.
<rc/spi.h>
It allows use of both dedicated hardware slave-select pins as well as GPIO pins for slave select. While this was developed on the BeagleBone platform, it should also work on Raspberry Pi and other embedded Linux systems.
For the Robotics Cape and BeagleBone blue, the SPI bus 1 is broken out on two JST SH 6-pin sockets labeled SPI1.1 and SPI1.2 These share clock and serial IO signals, but have independent slave select lines so two devices can share the same bus. Note that these ports labeled for slaves 1 and 2 correspond to slaves 0 and 1 in software. To make source code more clear, the macros RC_BB_SPI1_SS1 and RC_BB_SPI1_SS2 are provided in this header which are defined as 1,0 and 1,1. the GPIO channels corresponding to these slave select pins are also provided as macros in this header.For example:
pinout on Robotics Cape and BeagleBone Blue:
The slaves can be selected automatically by the SPI Linux driver or manually with rc_spi_select() function. On the Robotics Cape, slave 1 can be used in either mode, but slave 2 must be selected manually. On the BB Blue either slave can be used in manual or automatic modes. Only initialize once with either mode.
Macros | |
| #define | RC_SPI_MAX_SPEED 24000000 |
| 24mhz More... | |
| #define | RC_SPI_MIN_SPEED 1000 |
| 1khz More... | |
| #define | RC_SPI_BITS_PER_WORD 8 |
| only allow for 8-bit words More... | |
| #define | RC_BB_SPI1_SS1 1,0 |
| bus and slave to use for Robotics Cape and BeagleBone Blue SPI1.1 port More... | |
| #define | RC_BB_SPI1_SS2 1,1 |
| bus and slave to use for Robotics Cape and BeagleBone Blue SPI1.2 port More... | |
| #define | RC_CAPE_SS1_GPIO 3,17 |
| Robotics Cape SPI1 SS1 gpio P9_28, normally AUTO mode. More... | |
| #define | RC_CAPE_SS2_GPIO 1,17 |
| Robotics Cape SPI1 SS2 gpio P9_23, normally MANUAL GPIO mode. More... | |
| #define | RC_BLUE_SS1_GPIO 0,29 |
| BeagleBone Blue SPI1 SS1 gpio 0_29 pin H18. More... | |
| #define | RC_BLUE_SS2_GPIO 0,7 |
| BeagleBone Blue SPI1 SS2 gpio 0_7 pin H18. More... | |
Functions | |
| int | rc_spi_init_auto_slave (int bus, int slave, int bus_mode, int speed_hz) |
| Initializes an SPI bus. More... | |
| int | rc_spi_init_manual_slave (int bus, int slave, int bus_mode, int speed_hz, int chip, int pin) |
| Initializes an SPI bus and GPIO pin for use as a manual SPI slave select pin. More... | |
| int | rc_spi_get_fd (int bus, int slave) |
| fetches the file descriptor for a specified slave so the user can do more advanced IO operations than what's presented here More... | |
| int | rc_spi_close (int bus) |
| Closes and cleans up the bus for specified slave. More... | |
| int | rc_spi_manual_select (int bus, int slave, int select) |
| Manually selects or deselects a slave. More... | |
| int | rc_spi_transfer (int bus, int slave, uint8_t *tx_data, size_t tx_bytes, uint8_t *rx_data) |
| Send any sequence of bytes and read the response. More... | |
| int | rc_spi_write (int bus, int slave, uint8_t *data, size_t bytes) |
| Writes data to specified slave. More... | |
| int | rc_spi_read (int bus, int slave, uint8_t *data, size_t bytes) |
| Reads data from a specified slave. More... | |
| #define RC_SPI_MAX_SPEED 24000000 |
24mhz
| #define RC_SPI_MIN_SPEED 1000 |
1khz
| #define RC_SPI_BITS_PER_WORD 8 |
only allow for 8-bit words
| #define RC_BB_SPI1_SS1 1,0 |
bus and slave to use for Robotics Cape and BeagleBone Blue SPI1.1 port
| #define RC_BB_SPI1_SS2 1,1 |
bus and slave to use for Robotics Cape and BeagleBone Blue SPI1.2 port
| #define RC_CAPE_SS1_GPIO 3,17 |
Robotics Cape SPI1 SS1 gpio P9_28, normally AUTO mode.
| #define RC_CAPE_SS2_GPIO 1,17 |
Robotics Cape SPI1 SS2 gpio P9_23, normally MANUAL GPIO mode.
| #define RC_BLUE_SS1_GPIO 0,29 |
BeagleBone Blue SPI1 SS1 gpio 0_29 pin H18.
| #define RC_BLUE_SS2_GPIO 0,7 |
BeagleBone Blue SPI1 SS2 gpio 0_7 pin H18.
| int rc_spi_init_auto_slave | ( | int | bus, |
| int | slave, | ||
| int | bus_mode, | ||
| int | speed_hz | ||
| ) |
Initializes an SPI bus.
For description of the 4 SPI modes, see https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus#Mode_numbers
| [in] | bus | The bus |
| [in] | slave | The slave |
| [in] | bus_mode | SPI_MODE_0, SPI_MODE_1, SPI_MODE_2, or SPI_MODE_3 |
| [in] | speed_hz | The speed hz |
| int rc_spi_init_manual_slave | ( | int | bus, |
| int | slave, | ||
| int | bus_mode, | ||
| int | speed_hz, | ||
| int | chip, | ||
| int | pin | ||
| ) |
Initializes an SPI bus and GPIO pin for use as a manual SPI slave select pin.
The provided gpio chip/pin will then be remembered and tied to the provided slave number and bus. Note that on the BeagleBone and probably other platforms, there are only two files provided by the driver for interfacing to the bus, /dev/spi1.0 and /dev/spi1.1. When using a slave in manual mode, the first interface (slave 0 in software) will be used to talk to the manual slaves. Therefore this slave can not be used as an automatic slave.
For the BeagleBone Blue and RoboticsCape, this will also ensure that the pinmux is set correctly for that pin. The available manual slave select pins for these two boards are defined in this header for convenience. If using other boards it's up to the user to make sure the pin they are using is set up correctly in the device tree.
| [in] | bus | The spi bus |
| [in] | slave | The slave identifier (up to 16) |
| [in] | bus_mode | The bus mode |
| [in] | speed_hz | The speed hz |
| [in] | chip | The gpio chip |
| [in] | pin | The gpio pin |
| int rc_spi_get_fd | ( | int | bus, |
| int | slave | ||
| ) |
fetches the file descriptor for a specified slave so the user can do more advanced IO operations than what's presented here
| [in] | bus | The bus |
| [in] | slave | 0 or 1 |
| int rc_spi_close | ( | int | bus | ) |
Closes and cleans up the bus for specified slave.
| [in] | bus | SPI bus to close |
| int rc_spi_manual_select | ( | int | bus, |
| int | slave, | ||
| int | select | ||
| ) |
Manually selects or deselects a slave.
Only works if slave was initialized with SPI_SLAVE_MODE_MANUAL. If SPI_SLAVE_MODE_AUTO was selected then the SPI driver will handle this automatically when reading or writing.
| [in] | bus | SPI bus to use |
| [in] | slave | slave id |
| [in] | select | 0 to deselect, otherwise selects |
| int rc_spi_transfer | ( | int | bus, |
| int | slave, | ||
| uint8_t * | tx_data, | ||
| size_t | tx_bytes, | ||
| uint8_t * | rx_data | ||
| ) |
Send any sequence of bytes and read the response.
This is a wrapper for the ioctl spi transfer function and is generally what you will use for reading/writing device registers.
| [in] | bus | SPI bus to use |
| [in] | slave | slave id |
| [in] | tx_data | pointer to data to send |
| [in] | tx_bytes | number of bytes to send |
| rx_data | pointer to put response data |
| int rc_spi_write | ( | int | bus, |
| int | slave, | ||
| uint8_t * | data, | ||
| size_t | bytes | ||
| ) |
Writes data to specified slave.
| [in] | bus | SPI bus to use |
| [in] | slave | slave id |
| data | data pointer | |
| [in] | bytes | number of bytes to send |
| int rc_spi_read | ( | int | bus, |
| int | slave, | ||
| uint8_t * | data, | ||
| size_t | bytes | ||
| ) |
Reads data from a specified slave.
| [in] | bus | SPI bus to use |
| [in] | slave | slave id |
| data | data poitner | |
| [in] | bytes | number of bytes to read |
1.8.13