- 1 Broadcast Manager protocol sockets (SOCK_DGRAM)
- 1.1 Opening BCM sockets
- 1.2 BCM messages (struct bcm_msg_head)
- 1.3 TX_SETUP opcode
- 1.4 TX_DELETE opcode
- 1.5 TX_READ opcode
- 1.6 TX_SEND opcode
- 1.7 RX_SETUP opcode
- 1.8 RX_DELETE opcode
- 1.9 RX_READ opcode
+ B. Broadcast Manager protocol sockets (SOCK_DGRAM)
+ B.1 Opening BCM sockets
+ B.2 BCM messages (struct bcm_msg_head)
+ B.3 TX_SETUP opcode
+ B.4 TX_DELETE opcode
+ B.5 TX_READ opcode
+ B.6 TX_SEND opcode
+ B.7 RX_SETUP opcode
+ B.8 RX_DELETE opcode
+ B.9 RX_READ opcode
============================================================================
============================================================================
-1. Broadcast Manager protocol sockets (SOCK_DGRAM)
+B. Broadcast Manager protocol sockets (SOCK_DGRAM)
--------------------------------------------------
The Broadcast Manager (BCM) provides functions to send CAN frames
--------------------------------------------------
The Broadcast Manager (BCM) provides functions to send CAN frames
- Frequency reduction of messages (throttle function) to the user
application
- Frequency reduction of messages (throttle function) to the user
application
- 1.1 Opening BCM sockets
+ B.1 Opening BCM sockets
To use Broadcast-Manager include the file "bcm.h".
A socket for Broadcast-Manager is created with:
To use Broadcast-Manager include the file "bcm.h".
A socket for Broadcast-Manager is created with:
Every single instance of Broadcast-Manager is able to manage any number of
filter and/or send requests.
Every single instance of Broadcast-Manager is able to manage any number of
filter and/or send requests.
- 1.2 BCM messages (struct bcm_msg_head)
+ B.2 BCM messages (struct bcm_msg_head)
All messages from the (user) process to Broadcast-Manager have the same
structure. It consists of a message header with the command (opcode),
All messages from the (user) process to Broadcast-Manager have the same
structure. It consists of a message header with the command (opcode),
generated when the (cyclic) receive restarts. This will happen even
if the user data have not changed
generated when the (cyclic) receive restarts. This will happen even
if the user data have not changed
- 1.3 TX_SETUP opcode
- 1.4 TX_DELETE opcode
+ B.3 TX_SETUP opcode
+ B.4 TX_DELETE opcode
This opcode will delete the entry for transmission of the CAN frame with
the specified can_id CAN identifier. The message length for the command
TX_DELETE is sizeof(bcm_msg_head) (only the header).
This opcode will delete the entry for transmission of the CAN frame with
the specified can_id CAN identifier. The message length for the command
TX_DELETE is sizeof(bcm_msg_head) (only the header).
- 1.5 TX_READ opcode
- 1.6 TX_SEND opcode
- 1.7 RX_SETUP opcode
- 1.8 RX_DELETE opcode
- 1.9 RX_READ opcode
+ B.5 TX_READ opcode
+ B.6 TX_SEND opcode
+ B.7 RX_SETUP opcode
+ B.8 RX_DELETE opcode
+ B.9 RX_READ opcode
- 1 Socket CAN core module
- 1.1 can.ko module params
- 1.2 procfs content
- 1.3 writing own CAN protocol modules
+ C. Socket CAN core module
+ C.1 can.ko module params
+ C.2 procfs content
+ C.3 writing own CAN protocol modules
============================================================================
============================================================================
-1. Socket CAN core module
+C. Socket CAN core module
-------------------------
The Socket CAN core module implements the protocol family
-------------------------
The Socket CAN core module implements the protocol family
runtime. The core module provides an interface for CAN protocol
modules to subscribe needed CAN IDs (see overview.txt, chapter 3.1).
runtime. The core module provides an interface for CAN protocol
modules to subscribe needed CAN IDs (see overview.txt, chapter 3.1).
- 1.1 can.ko module params
+ C.1 can.ko module params
- stats_timer: To calculate the Socket CAN core statistics
(e.g. current/maximum frames per second) this 1 second timer is
- stats_timer: To calculate the Socket CAN core statistics
(e.g. current/maximum frames per second) this 1 second timer is
- debug: (removed since SocketCAN SVN r546)
- debug: (removed since SocketCAN SVN r546)
As described in overview.txt, chapter 3.1 the Socket CAN core uses
several filter lists to deliver received CAN frames to CAN protocol
As described in overview.txt, chapter 3.1 the Socket CAN core uses
several filter lists to deliver received CAN frames to CAN protocol
reset_stats - manual statistic reset
version - prints the Socket CAN core version and the ABI version
reset_stats - manual statistic reset
version - prints the Socket CAN core version and the ABI version
- 1.3 writing own CAN protocol modules
+ C.3 writing own CAN protocol modules
To implement a new protocol in the protocol family PF_CAN a new
protocol has to be defined in include/linux/can.h .
To implement a new protocol in the protocol family PF_CAN a new
protocol has to be defined in include/linux/can.h .
- 1 CAN network drivers
- 1.1 general settings
- 1.2 local loopback of sent frames
- 1.3 CAN controller hardware filters
- 1.4 The virtual CAN driver (vcan)
- 1.5 The CAN network device driver interface
- 1.5.1 Netlink interface to set/get devices properties
- 1.5.2 Setting the CAN bit-timing
- 1.5.3 Starting and stopping the CAN network device
- 1.6 supported CAN hardware
+ D. CAN network drivers
+ D.1 general settings
+ D.2 local loopback of sent frames
+ D.3 CAN controller hardware filters
+ D.4 The virtual CAN driver (vcan)
+ D.5 The CAN network device driver interface
+ D.5.1 Netlink interface to set/get devices properties
+ D.5.2 Setting the CAN bit-timing
+ D.5.3 Starting and stopping the CAN network device
+ D.6 supported CAN hardware
============================================================================
============================================================================
----------------------
Writing a CAN network device driver is much easier than writing a
----------------------
Writing a CAN network device driver is much easier than writing a
See e.g. at Documentation/networking/netdevices.txt . The differences
for writing CAN network device driver are described below:
See e.g. at Documentation/networking/netdevices.txt . The differences
for writing CAN network device driver are described below:
dev->type = ARPHRD_CAN; /* the netdevice hardware type */
dev->flags = IFF_NOARP; /* CAN has no arp */
dev->type = ARPHRD_CAN; /* the netdevice hardware type */
dev->flags = IFF_NOARP; /* CAN has no arp */
The struct can_frame is the payload of each socket buffer in the
protocol family PF_CAN.
The struct can_frame is the payload of each socket buffer in the
protocol family PF_CAN.
- 1.2 local loopback of sent frames
+ D.2 local loopback of sent frames
- As described in can-sockets.txt (chapter 1.2) the CAN network device
+ As described in overview.txt (chapter 3.2) the CAN network device
driver should support a local loopback functionality similar to the
local echo e.g. of tty devices. In this case the driver flag IFF_ECHO
has to be set to prevent the PF_CAN core from locally echoing sent
driver should support a local loopback functionality similar to the
local echo e.g. of tty devices. In this case the driver flag IFF_ECHO
has to be set to prevent the PF_CAN core from locally echoing sent
dev->flags = (IFF_NOARP | IFF_ECHO);
dev->flags = (IFF_NOARP | IFF_ECHO);
- 1.3 CAN controller hardware filters
+ D.3 CAN controller hardware filters
To reduce the interrupt load on deep embedded systems some CAN
controllers support the filtering of CAN IDs or ranges of CAN IDs.
To reduce the interrupt load on deep embedded systems some CAN
controllers support the filtering of CAN IDs or ranges of CAN IDs.
@133MHz with four SJA1000 CAN controllers from 2002 under heavy bus
load without any problems ...
@133MHz with four SJA1000 CAN controllers from 2002 under heavy bus
load without any problems ...
- 1.4 The virtual CAN driver (vcan)
+ D.4 The virtual CAN driver (vcan)
Similar to the network loopback devices, vcan offers a virtual local
CAN interface. A full qualified address on CAN consists of
Similar to the network loopback devices, vcan offers a virtual local
CAN interface. A full qualified address on CAN consists of
- Remove a (virtual CAN) network interface 'vcan42':
$ ip link del vcan42
- Remove a (virtual CAN) network interface 'vcan42':
$ ip link del vcan42
- 1.5 The CAN network device driver interface
+ D.5 The CAN network device driver interface
The CAN network device driver interface provides a generic interface
to setup, configure and monitor CAN network devices. The user can then
The CAN network device driver interface provides a generic interface
to setup, configure and monitor CAN network devices. The user can then
should use. Please have a look to the SJA1000 or MSCAN driver to
understand how to use them. The name of the module is can-dev.ko.
should use. Please have a look to the SJA1000 or MSCAN driver to
understand how to use them. The name of the module is can-dev.ko.
- 1.5.1 Netlink interface to set/get devices properties
+ D.5.1 Netlink interface to set/get devices properties
The CAN device must be configured via netlink interface. The supported
netlink message types are defined and briefly described in
The CAN device must be configured via netlink interface. The supported
netlink message types are defined and briefly described in
bus-off state. RX overrun errors are listed in the "overrun"
field of the standard network statistics.
bus-off state. RX overrun errors are listed in the "overrun"
field of the standard network statistics.
- 1.5.2 Setting the CAN bit-timing
+ D.5.2 Setting the CAN bit-timing
The CAN bit-timing parameters can always be defined in a hardware
independent format as proposed in the Bosch CAN 2.0 specification
The CAN bit-timing parameters can always be defined in a hardware
independent format as proposed in the Bosch CAN 2.0 specification
$ ip link set canX type can restart
Note that a restart will also create a CAN error frame (see also
$ ip link set canX type can restart
Note that a restart will also create a CAN error frame (see also
- can-sockets.txt, chapter 1.4).
+ overview.txt, chapter 3.4).
- 1.6 Supported CAN hardware
+ D.6 Supported CAN hardware
Please check the "Kconfig" file in "drivers/net/can" to get an actual
list of the support CAN hardware. On the Socket CAN project website
Please check the "Kconfig" file in "drivers/net/can" to get an actual
list of the support CAN hardware. On the Socket CAN project website
- (see overview.txt, chapter 5) there might be further drivers available,
+ (see overview.txt, chapter 4) there might be further drivers available,
also for older kernel versions.
also for older kernel versions.
- 1 RAW protocol sockets with can_filters (SOCK_RAW)
- 1.1 RAW socket option CAN_RAW_FILTER
- 1.2 RAW socket option CAN_RAW_ERR_FILTER
- 1.3 RAW socket option CAN_RAW_LOOPBACK
- 1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
- 1.5 RAW socket returned message flags
+ R. RAW protocol sockets with can_filters (SOCK_RAW)
+ R.1 RAW socket option CAN_RAW_FILTER
+ R.2 RAW socket option CAN_RAW_ERR_FILTER
+ R.3 RAW socket option CAN_RAW_LOOPBACK
+ R.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
+ R.5 RAW socket returned message flags
============================================================================
============================================================================
-1. RAW protocol sockets with can_filters (SOCK_RAW)
+R. RAW protocol sockets with can_filters (SOCK_RAW)
---------------------------------------------------
Using CAN_RAW sockets is extensively comparable to the commonly
---------------------------------------------------
Using CAN_RAW sockets is extensively comparable to the commonly
To use the referenced definitions of the socket options for CAN_RAW
sockets, include <linux/can/raw.h>.
To use the referenced definitions of the socket options for CAN_RAW
sockets, include <linux/can/raw.h>.
- 1.1 RAW socket option CAN_RAW_FILTER
+ R.1 RAW socket option CAN_RAW_FILTER
The reception of CAN frames using CAN_RAW sockets can be controlled
by defining 0 .. n filters with the CAN_RAW_FILTER socket option.
The reception of CAN frames using CAN_RAW sockets can be controlled
by defining 0 .. n filters with the CAN_RAW_FILTER socket option.
having this 'send only' use-case we may remove the receive list in the
Kernel to save a little (really a very little!) CPU usage.
having this 'send only' use-case we may remove the receive list in the
Kernel to save a little (really a very little!) CPU usage.
- 1.2 RAW socket option CAN_RAW_ERR_FILTER
+ R.2 RAW socket option CAN_RAW_ERR_FILTER
As described in overview.txt (chapter 3.4) the CAN interface driver
can generate so called Error Frames that can optionally be passed
As described in overview.txt (chapter 3.4) the CAN interface driver
can generate so called Error Frames that can optionally be passed
setsockopt(s, SOL_CAN_RAW, CAN_RAW_ERR_FILTER,
&err_mask, sizeof(err_mask));
setsockopt(s, SOL_CAN_RAW, CAN_RAW_ERR_FILTER,
&err_mask, sizeof(err_mask));
- 1.3 RAW socket option CAN_RAW_LOOPBACK
+ R.3 RAW socket option CAN_RAW_LOOPBACK
To meet multi user needs the local loopback is enabled by default
(see overview.txt, chapter 3.2, for details). But in some embedded
To meet multi user needs the local loopback is enabled by default
(see overview.txt, chapter 3.2, for details). But in some embedded
setsockopt(s, SOL_CAN_RAW, CAN_RAW_LOOPBACK, &loopback, sizeof(loopback));
setsockopt(s, SOL_CAN_RAW, CAN_RAW_LOOPBACK, &loopback, sizeof(loopback));
- 1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
+ R.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
When the local loopback is enabled, all the sent CAN frames are
looped back to the open CAN sockets that registered for the CAN
When the local loopback is enabled, all the sent CAN frames are
looped back to the open CAN sockets that registered for the CAN
setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
&recv_own_msgs, sizeof(recv_own_msgs));
setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
&recv_own_msgs, sizeof(recv_own_msgs));
- 1.5 RAW socket returned message flags
+ R.5 RAW socket returned message flags
When using recvmsg() call, the msg->msg_flags may contain following flags:
When using recvmsg() call, the msg->msg_flags may contain following flags:
- 1 How to use Socket CAN
- 1.1 Timestamps
+ S. How to use Socket CAN
+ S.1 Timestamps
============================================================================
============================================================================
-1. How to use Socket CAN
+S. How to use Socket CAN
------------------------
Like TCP/IP, you first need to open a socket for communicating over a
------------------------
Like TCP/IP, you first need to open a socket for communicating over a
nbytes = sendto(s, &frame, sizeof(struct can_frame),
0, (struct sockaddr*)&addr, sizeof(addr));
nbytes = sendto(s, &frame, sizeof(struct can_frame),
0, (struct sockaddr*)&addr, sizeof(addr));
For applications in the CAN environment it is often of interest an
accurate timestamp of the instant a message from CAN bus has been received.
For applications in the CAN environment it is often of interest an
accurate timestamp of the instant a message from CAN bus has been received.
data has to be performed right after a successful transmission. If
the CAN network interface is not capable of performing the loopback for
some reason the SocketCAN core can do this task as a fallback solution.
data has to be performed right after a successful transmission. If
the CAN network interface is not capable of performing the loopback for
some reason the SocketCAN core can do this task as a fallback solution.
- See can-drivers.txt, chapter 1.2 for details (recommended).
+ See can-drivers.txt, chapter D.2 for details (recommended).
The loopback functionality is enabled by default to reflect standard
networking behaviour for CAN applications. Due to some requests from
The loopback functionality is enabled by default to reflect standard
networking behaviour for CAN applications. Due to some requests from
projects / socketcan-devel.git / commitdiff