class Tinkerforge::BrickletCANV2
Communicates with CAN bus devices
Constants
- CALLBACK_ERROR_OCCURRED
This callback is triggered if any error occurred while writing, reading or transmitting CAN frames.
The callback is only triggered once until
BrickletCANV2#get_error_log
is called. That function will return details abount the error(s) occurred.To enable this callback, use
BrickletCANV2#set_error_occurred_callback_configuration
.- .. versionadded
-
2.0.3$nbsp;(Plugin)
- CALLBACK_FRAME_READ
This callback is triggered if a data or remote frame was received by the CAN transceiver.
The “identifier“ return value follows the identifier format described for
BrickletCANV2#write_frame
.For details on the “data“ return value see
BrickletCANV2#read_frame
.A configurable read filter can be used to define which frames should be received by the CAN transceiver and put into the read queue (see
BrickletCANV2#set_read_filter_configuration
).To enable this callback, use
BrickletCANV2#set_frame_read_callback_configuration
.- .. note
-
If reconstructing the value fails, the callback is triggered with nil for data.
- CALLBACK_FRAME_READABLE
This callback is triggered if a data or remote frame was received by the CAN transceiver. The received frame can be read with
BrickletCANV2#read_frame
. If additional frames are received, butBrickletCANV2#read_frame
was not called yet, the callback will not trigger again.A configurable read filter can be used to define which frames should be received by the CAN transceiver and put into the read queue (see
BrickletCANV2#set_read_filter_configuration
).To enable this callback, use
BrickletCANV2#set_frame_readable_callback_configuration
.- .. versionadded
-
2.0.3$nbsp;(Plugin)
- CALLBACK_FRAME_READ_LOW_LEVEL
Public Class Methods
Creates an object with the unique device ID uid
and adds it to the IP Connection ipcon
.
# File lib/tinkerforge/bricklet_can_v2.rb, line 137 def initialize(uid, ipcon) super uid, ipcon, DEVICE_IDENTIFIER, DEVICE_DISPLAY_NAME @api_version = [2, 0, 1] @response_expected[FUNCTION_WRITE_FRAME_LOW_LEVEL] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_READ_FRAME_LOW_LEVEL] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_FRAME_READ_CALLBACK_CONFIGURATION] = RESPONSE_EXPECTED_TRUE @response_expected[FUNCTION_GET_FRAME_READ_CALLBACK_CONFIGURATION] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_TRANSCEIVER_CONFIGURATION] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_GET_TRANSCEIVER_CONFIGURATION] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_QUEUE_CONFIGURATION_LOW_LEVEL] = RESPONSE_EXPECTED_TRUE @response_expected[FUNCTION_GET_QUEUE_CONFIGURATION_LOW_LEVEL] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_READ_FILTER_CONFIGURATION] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_GET_READ_FILTER_CONFIGURATION] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_GET_ERROR_LOG_LOW_LEVEL] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_COMMUNICATION_LED_CONFIG] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_GET_COMMUNICATION_LED_CONFIG] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_ERROR_LED_CONFIG] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_GET_ERROR_LED_CONFIG] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_FRAME_READABLE_CALLBACK_CONFIGURATION] = RESPONSE_EXPECTED_TRUE @response_expected[FUNCTION_GET_FRAME_READABLE_CALLBACK_CONFIGURATION] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_ERROR_OCCURRED_CALLBACK_CONFIGURATION] = RESPONSE_EXPECTED_TRUE @response_expected[FUNCTION_GET_ERROR_OCCURRED_CALLBACK_CONFIGURATION] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_GET_SPITFP_ERROR_COUNT] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_BOOTLOADER_MODE] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_GET_BOOTLOADER_MODE] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_WRITE_FIRMWARE_POINTER] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_WRITE_FIRMWARE] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_SET_STATUS_LED_CONFIG] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_GET_STATUS_LED_CONFIG] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_GET_CHIP_TEMPERATURE] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_RESET] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_WRITE_UID] = RESPONSE_EXPECTED_FALSE @response_expected[FUNCTION_READ_UID] = RESPONSE_EXPECTED_ALWAYS_TRUE @response_expected[FUNCTION_GET_IDENTITY] = RESPONSE_EXPECTED_ALWAYS_TRUE @callback_formats[CALLBACK_FRAME_READ_LOW_LEVEL] = [29, 'C L C C15'] @callback_formats[CALLBACK_FRAME_READABLE] = [8, ''] @callback_formats[CALLBACK_ERROR_OCCURRED] = [8, ''] @high_level_callbacks[CALLBACK_FRAME_READ] = [[nil, nil, 'stream_length', 'stream_chunk_data'], {'fixed_length' => nil, 'single_chunk' => true}, nil] @ipcon.add_device self end
Public Instance Methods
Returns the current bootloader mode, see BrickletCANV2#set_bootloader_mode
.
# File lib/tinkerforge/bricklet_can_v2.rb, line 572 def get_bootloader_mode check_validity send_request FUNCTION_GET_BOOTLOADER_MODE, [], '', 9, 'C' end
Returns the temperature as measured inside the microcontroller. The value returned is not the ambient temperature!
The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.
# File lib/tinkerforge/bricklet_can_v2.rb, line 630 def get_chip_temperature check_validity send_request FUNCTION_GET_CHIP_TEMPERATURE, [], '', 10, 's' end
Returns the configuration as set by BrickletCANV2#set_communication_led_config
# File lib/tinkerforge/bricklet_can_v2.rb, line 467 def get_communication_led_config check_validity send_request FUNCTION_GET_COMMUNICATION_LED_CONFIG, [], '', 9, 'C' end
Returns the configuration as set by BrickletCANV2#set_error_led_config
.
# File lib/tinkerforge/bricklet_can_v2.rb, line 493 def get_error_led_config check_validity send_request FUNCTION_GET_ERROR_LED_CONFIG, [], '', 9, 'C' end
Returns information about different kinds of errors.
The write and read error levels indicate the current level of stuffing, form, acknowledgement, bit and checksum errors during CAN bus write and read operations. For each of this error kinds there is also an individual counter.
When the write error level extends 255 then the CAN transceiver gets disabled and no frames can be transmitted or received anymore. The CAN transceiver will automatically be activated again after the CAN bus is idle for a while.
The write buffer timeout, read buffer and backlog overflow counts represents the number of these errors:
-
A write buffer timeout occurs if a frame could not be transmitted before the configured write buffer timeout expired (see
BrickletCANV2#set_queue_configuration
). -
A read buffer overflow occurs if a read buffer of the CAN transceiver still contains the last received frame when the next frame arrives. In this case the last received frame is lost. This happens if the CAN transceiver receives more frames than the Bricklet can handle. Using the read filter (see
BrickletCANV2#set_read_filter_configuration
) can help to reduce the amount of received frames. This count is not exact, but a lower bound, because the Bricklet might not able detect all overflows if they occur in rapid succession. -
A read backlog overflow occurs if the read backlog of the Bricklet is already full when the next frame should be read from a read buffer of the CAN transceiver. In this case the frame in the read buffer is lost. This happens if the CAN transceiver receives more frames to be added to the read backlog than are removed from the read backlog using the
BrickletCANV2#read_frame
function. Using theCALLBACK_FRAME_READ
callback ensures that the read backlog can not overflow.
The read buffer overflow counter counts the overflows of all configured read buffers. Which read buffer exactly suffered from an overflow can be figured out from the read buffer overflow occurrence list (“read_buffer_overflow_error_occurred“). Reading the error log clears the occurence list.
# File lib/tinkerforge/bricklet_can_v2.rb, line 858 def get_error_log ret = get_error_log_low_level [ret[0], ret[1], ret[2], ret[3], ret[4], ret[5], ret[6], ret[7], ret[8], ret[9], ret[10], ret[12][0, ret[11]], ret[13]] end
Returns information about different kinds of errors.
The write and read error levels indicate the current level of stuffing, form, acknowledgement, bit and checksum errors during CAN bus write and read operations. For each of this error kinds there is also an individual counter.
When the write error level extends 255 then the CAN transceiver gets disabled and no frames can be transmitted or received anymore. The CAN transceiver will automatically be activated again after the CAN bus is idle for a while.
The write buffer timeout, read buffer and backlog overflow counts represents the number of these errors:
-
A write buffer timeout occurs if a frame could not be transmitted before the configured write buffer timeout expired (see
BrickletCANV2#set_queue_configuration
). -
A read buffer overflow occurs if a read buffer of the CAN transceiver still contains the last received frame when the next frame arrives. In this case the last received frame is lost. This happens if the CAN transceiver receives more frames than the Bricklet can handle. Using the read filter (see
BrickletCANV2#set_read_filter_configuration
) can help to reduce the amount of received frames. This count is not exact, but a lower bound, because the Bricklet might not able detect all overflows if they occur in rapid succession. -
A read backlog overflow occurs if the read backlog of the Bricklet is already full when the next frame should be read from a read buffer of the CAN transceiver. In this case the frame in the read buffer is lost. This happens if the CAN transceiver receives more frames to be added to the read backlog than are removed from the read backlog using the
BrickletCANV2#read_frame
function. Using theCALLBACK_FRAME_READ
callback ensures that the read backlog can not overflow.
The read buffer overflow counter counts the overflows of all configured read buffers. Which read buffer exactly suffered from an overflow can be figured out from the read buffer overflow occurrence list (“read_buffer_overflow_error_occurred“). Reading the error log clears the occurence list.
# File lib/tinkerforge/bricklet_can_v2.rb, line 448 def get_error_log_low_level check_validity send_request FUNCTION_GET_ERROR_LOG_LOW_LEVEL, [], '', 52, 'C C C L L L L L L L L C ?32 L' end
Returns true if the CALLBACK_ERROR_OCCURRED
callback is enabled, false otherwise.
- .. versionadded
-
2.0.3$nbsp;(Plugin)
# File lib/tinkerforge/bricklet_can_v2.rb, line 533 def get_error_occurred_callback_configuration check_validity send_request FUNCTION_GET_ERROR_OCCURRED_CALLBACK_CONFIGURATION, [], '', 9, '?' end
Returns true if the CALLBACK_FRAME_READ
callback is enabled, false otherwise.
# File lib/tinkerforge/bricklet_can_v2.rb, line 254 def get_frame_read_callback_configuration check_validity send_request FUNCTION_GET_FRAME_READ_CALLBACK_CONFIGURATION, [], '', 9, '?' end
Returns true if the CALLBACK_FRAME_READABLE
callback is enabled, false otherwise.
- .. versionadded
-
2.0.3$nbsp;(Plugin)
# File lib/tinkerforge/bricklet_can_v2.rb, line 513 def get_frame_readable_callback_configuration check_validity send_request FUNCTION_GET_FRAME_READABLE_CALLBACK_CONFIGURATION, [], '', 9, '?' end
Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.
The position can be 'a', 'b', 'c', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an :ref:`Isolator Bricklet <isolator_bricklet>` is always at position 'z'.
The device identifier numbers can be found :ref:`here <device_identifier>`. |device_identifier_constant|
# File lib/tinkerforge/bricklet_can_v2.rb, line 677 def get_identity send_request FUNCTION_GET_IDENTITY, [], '', 33, 'Z8 Z8 k C3 C3 S' end
Returns the queue configuration as set by BrickletCANV2#set_queue_configuration
.
# File lib/tinkerforge/bricklet_can_v2.rb, line 817 def get_queue_configuration ret = get_queue_configuration_low_level [ret[0], ret[1], ret[2], ret[4][0, ret[3]], ret[5]] end
Returns the queue configuration as set by BrickletCANV2#set_queue_configuration
.
# File lib/tinkerforge/bricklet_can_v2.rb, line 338 def get_queue_configuration_low_level check_validity send_request FUNCTION_GET_QUEUE_CONFIGURATION_LOW_LEVEL, [], '', 50, 'C l S C c32 S' end
Returns the read filter configuration as set by BrickletCANV2#set_read_filter_configuration
.
# File lib/tinkerforge/bricklet_can_v2.rb, line 407 def get_read_filter_configuration(buffer_index) check_validity send_request FUNCTION_GET_READ_FILTER_CONFIGURATION, [buffer_index], 'C', 17, 'C L L' end
Returns the error count for the communication between Brick and Bricklet.
The errors are divided into
-
ACK checksum errors,
-
message checksum errors,
-
framing errors and
-
overflow errors.
The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.
# File lib/tinkerforge/bricklet_can_v2.rb, line 550 def get_spitfp_error_count check_validity send_request FUNCTION_GET_SPITFP_ERROR_COUNT, [], '', 24, 'L L L L' end
Returns the configuration as set by BrickletCANV2#set_status_led_config
# File lib/tinkerforge/bricklet_can_v2.rb, line 618 def get_status_led_config check_validity send_request FUNCTION_GET_STATUS_LED_CONFIG, [], '', 9, 'C' end
Returns the configuration as set by BrickletCANV2#set_transceiver_configuration
.
# File lib/tinkerforge/bricklet_can_v2.rb, line 278 def get_transceiver_configuration check_validity send_request FUNCTION_GET_TRANSCEIVER_CONFIGURATION, [], '', 15, 'L S C' end
Tries to read the next data or remote frame from the read queue and returns it. If a frame was successfully read, then the “success“ return value is set to true and the other return values contain the frame. If the read queue is empty and no frame could be read, then the “success“ return value is set to false and the other return values contain invalid data.
The “identifier“ return value follows the identifier format described for BrickletCANV2#write_frame
.
The “data“ return value can be up to 15 bytes long. For data frames up to the first 8 bytes are the actual received data. All bytes after the 8th byte are always zero and only there to indicate the length of a data or remote frame with excess length. For remote frames the length of the “data“ return value represents the requested length. The actual “data“ bytes are always zero.
A configurable read filter can be used to define which frames should be received by the CAN transceiver and put into the read queue (see BrickletCANV2#set_read_filter_configuration
).
Instead of polling with this function, you can also use callbacks. See the BrickletCANV2#set_frame_read_callback_configuration
function and the CALLBACK_FRAME_READ
callback.
# File lib/tinkerforge/bricklet_can_v2.rb, line 747 def read_frame ret = read_frame_low_level [ret[0], ret[1], ret[2], ret[4][0, ret[3]]] end
Tries to read the next data or remote frame from the read queue and returns it. If a frame was successfully read, then the “success“ return value is set to true and the other return values contain the frame. If the read queue is empty and no frame could be read, then the “success“ return value is set to false and the other return values contain invalid data.
The “identifier“ return value follows the identifier format described for BrickletCANV2#write_frame
.
The “data“ return value can be up to 15 bytes long. For data frames up to the first 8 bytes are the actual received data. All bytes after the 8th byte are always zero and only there to indicate the length of a data or remote frame with excess length. For remote frames the length of the “data“ return value represents the requested length. The actual “data“ bytes are always zero.
A configurable read filter can be used to define which frames should be received by the CAN transceiver and put into the read queue (see BrickletCANV2#set_read_filter_configuration
).
Instead of polling with this function, you can also use callbacks. See the BrickletCANV2#set_frame_read_callback_configuration
function and the CALLBACK_FRAME_READ
callback.
# File lib/tinkerforge/bricklet_can_v2.rb, line 238 def read_frame_low_level check_validity send_request FUNCTION_READ_FRAME_LOW_LEVEL, [], '', 30, '? C L C C15' end
Returns the current UID as an integer. Encode as Base58
to get the usual string version.
# File lib/tinkerforge/bricklet_can_v2.rb, line 661 def read_uid check_validity send_request FUNCTION_READ_UID, [], '', 12, 'L' end
Registers a callback with ID id
to the block block
.
# File lib/tinkerforge/bricklet_can_v2.rb, line 865 def register_callback(id, &block) callback = block @registered_callbacks[id] = callback end
Calling this function will reset the Bricklet. All configurations will be lost.
After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!
# File lib/tinkerforge/bricklet_can_v2.rb, line 642 def reset check_validity send_request FUNCTION_RESET, [], '', 8, '' end
Sets the bootloader mode and returns the status after the requested mode change was instigated.
You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.
This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.
# File lib/tinkerforge/bricklet_can_v2.rb, line 565 def set_bootloader_mode(mode) check_validity send_request FUNCTION_SET_BOOTLOADER_MODE, [mode], 'C', 9, 'C' end
Sets the communication LED configuration. By default the LED shows CAN-Bus traffic, it flickers once for every 40 transmitted or received frames.
You can also turn the LED permanently on/off or show a heartbeat.
If the Bricklet is in bootloader mode, the LED is off.
# File lib/tinkerforge/bricklet_can_v2.rb, line 460 def set_communication_led_config(config) check_validity send_request FUNCTION_SET_COMMUNICATION_LED_CONFIG, [config], 'C', 8, '' end
Sets the error LED configuration.
By default (show-transceiver-state) the error LED turns on if the CAN transceiver is passive or disabled state (see BrickletCANV2#get_error_log
). If the CAN transceiver is in active state the LED turns off.
If the LED is configured as show-error then the error LED turns on if any error occurs. If you call this function with the show-error option again, the LED will turn off until the next error occurs.
You can also turn the LED permanently on/off or show a heartbeat.
If the Bricklet is in bootloader mode, the LED is off.
# File lib/tinkerforge/bricklet_can_v2.rb, line 486 def set_error_led_config(config) check_validity send_request FUNCTION_SET_ERROR_LED_CONFIG, [config], 'C', 8, '' end
Enables and disables the CALLBACK_ERROR_OCCURRED
callback.
By default the callback is disabled.
- .. versionadded
-
2.0.3$nbsp;(Plugin)
# File lib/tinkerforge/bricklet_can_v2.rb, line 524 def set_error_occurred_callback_configuration(enabled) check_validity send_request FUNCTION_SET_ERROR_OCCURRED_CALLBACK_CONFIGURATION, [enabled], '?', 8, '' end
Enables and disables the CALLBACK_FRAME_READ
callback.
By default the callback is disabled. Enabling this callback will disable the CALLBACK_FRAME_READABLE
callback.
# File lib/tinkerforge/bricklet_can_v2.rb, line 247 def set_frame_read_callback_configuration(enabled) check_validity send_request FUNCTION_SET_FRAME_READ_CALLBACK_CONFIGURATION, [enabled], '?', 8, '' end
Enables and disables the CALLBACK_FRAME_READABLE
callback.
By default the callback is disabled. Enabling this callback will disable the CALLBACK_FRAME_READ
callback.
- .. versionadded
-
2.0.3$nbsp;(Plugin)
# File lib/tinkerforge/bricklet_can_v2.rb, line 504 def set_frame_readable_callback_configuration(enabled) check_validity send_request FUNCTION_SET_FRAME_READABLE_CALLBACK_CONFIGURATION, [enabled], '?', 8, '' end
Sets the write and read queue configuration.
The CAN transceiver has 32 buffers in total in hardware for transmitting and receiving frames. Additionally, the Bricklet has a backlog for 768 frames in total in software. The buffers and the backlog can be freely assigned to the write and read queues.
BrickletCANV2#write_frame
writes a frame into the write backlog. The Bricklet moves the frame from the backlog into a free write buffer. The CAN transceiver then transmits the frame from the write buffer to the CAN bus. If there are no write buffers (“write_buffer_size“ is zero) or there is no write backlog (“write_backlog_size“ is zero) then no frames can be transmitted and BrickletCANV2#write_frame
returns always false.
The CAN transceiver receives a frame from the CAN bus and stores it into a free read buffer. The Bricklet moves the frame from the read buffer into the read backlog. BrickletCANV2#read_frame
reads the frame from the read backlog and returns it. If there are no read buffers (“read_buffer_sizes“ is empty) or there is no read backlog (“read_backlog_size“ is zero) then no frames can be received and BrickletCANV2#read_frame
returns always false.
There can be multiple read buffers, because the CAN transceiver cannot receive data and remote frames into the same read buffer. A positive read buffer size represents a data frame read buffer and a negative read buffer size represents a remote frame read buffer. A read buffer size of zero is not allowed. By default the first read buffer is configured for data frames and the second read buffer is configured for remote frame. There can be up to 32 different read buffers, assuming that no write buffer is used. Each read buffer has its own filter configuration (see BrickletCANV2#set_read_filter_configuration
).
- A valid queue configuration fulfills these conditions
-
write_buffer_size + abs(read_buffer_size_0) + abs(read_buffer_size_1) + … + abs(read_buffer_size_31) <= 32 write_backlog_size + read_backlog_size <= 768
The write buffer timeout has three different modes that define how a failed frame transmission should be handled:
-
Single-Shot (< 0): Only one transmission attempt will be made. If the transmission fails then the frame is discarded.
-
Infinite (= 0): Infinite transmission attempts will be made. The frame will never be discarded.
-
Milliseconds (> 0): A limited number of transmission attempts will be made. If the frame could not be transmitted successfully after the configured number of milliseconds then the frame is discarded.
The current content of the queues is lost when this function is called.
# File lib/tinkerforge/bricklet_can_v2.rb, line 800 def set_queue_configuration(write_buffer_size, write_buffer_timeout, write_backlog_size, read_buffer_sizes, read_backlog_size) read_buffer_sizes = read_buffer_sizes.clone # clone so we can potentially extend it read_buffer_sizes_length = read_buffer_sizes.length read_buffer_sizes_data = read_buffer_sizes if read_buffer_sizes_length > 32 raise ArgumentError, 'Read Buffer Sizes can be at most 32 items long' end if read_buffer_sizes_length < 32 read_buffer_sizes_data += [0] * (32 - read_buffer_sizes_length) end set_queue_configuration_low_level write_buffer_size, write_buffer_timeout, write_backlog_size, read_buffer_sizes_length, read_buffer_sizes_data, read_backlog_size end
Sets the write and read queue configuration.
The CAN transceiver has 32 buffers in total in hardware for transmitting and receiving frames. Additionally, the Bricklet has a backlog for 768 frames in total in software. The buffers and the backlog can be freely assigned to the write and read queues.
BrickletCANV2#write_frame
writes a frame into the write backlog. The Bricklet moves the frame from the backlog into a free write buffer. The CAN transceiver then transmits the frame from the write buffer to the CAN bus. If there are no write buffers (“write_buffer_size“ is zero) or there is no write backlog (“write_backlog_size“ is zero) then no frames can be transmitted and BrickletCANV2#write_frame
returns always false.
The CAN transceiver receives a frame from the CAN bus and stores it into a free read buffer. The Bricklet moves the frame from the read buffer into the read backlog. BrickletCANV2#read_frame
reads the frame from the read backlog and returns it. If there are no read buffers (“read_buffer_sizes“ is empty) or there is no read backlog (“read_backlog_size“ is zero) then no frames can be received and BrickletCANV2#read_frame
returns always false.
There can be multiple read buffers, because the CAN transceiver cannot receive data and remote frames into the same read buffer. A positive read buffer size represents a data frame read buffer and a negative read buffer size represents a remote frame read buffer. A read buffer size of zero is not allowed. By default the first read buffer is configured for data frames and the second read buffer is configured for remote frame. There can be up to 32 different read buffers, assuming that no write buffer is used. Each read buffer has its own filter configuration (see BrickletCANV2#set_read_filter_configuration
).
- A valid queue configuration fulfills these conditions
-
write_buffer_size + abs(read_buffer_size_0) + abs(read_buffer_size_1) + … + abs(read_buffer_size_31) <= 32 write_backlog_size + read_backlog_size <= 768
The write buffer timeout has three different modes that define how a failed frame transmission should be handled:
-
Single-Shot (< 0): Only one transmission attempt will be made. If the transmission fails then the frame is discarded.
-
Infinite (= 0): Infinite transmission attempts will be made. The frame will never be discarded.
-
Milliseconds (> 0): A limited number of transmission attempts will be made. If the frame could not be transmitted successfully after the configured number of milliseconds then the frame is discarded.
The current content of the queues is lost when this function is called.
# File lib/tinkerforge/bricklet_can_v2.rb, line 331 def set_queue_configuration_low_level(write_buffer_size, write_buffer_timeout, write_backlog_size, read_buffer_sizes_length, read_buffer_sizes_data, read_backlog_size) check_validity send_request FUNCTION_SET_QUEUE_CONFIGURATION_LOW_LEVEL, [write_buffer_size, write_buffer_timeout, write_backlog_size, read_buffer_sizes_length, read_buffer_sizes_data, read_backlog_size], 'C l S C c32 S', 8, '' end
Set the read filter configuration for the given read buffer index. This can be used to define which frames should be received by the CAN transceiver and put into the read buffer.
The read filter has four different modes that define if and how the filter mask and the filter identifier are applied:
-
Accept-All: All frames are received.
-
Match-Standard-Only: Only standard frames with a matching identifier are received.
-
Match-Extended-Only: Only extended frames with a matching identifier are received.
-
Match-Standard-And-Extended: Standard and extended frames with a matching identifier are received.
The filter mask and filter identifier are used as bit masks. Their usage depends on the mode:
-
Accept-All: Mask and identifier are ignored.
-
Match-Standard-Only: Bit 0 to 10 (11 bits) of filter mask and filter identifier are used to match the 11-bit identifier of standard frames.
-
Match-Extended-Only: Bit 0 to 28 (29 bits) of filter mask and filter identifier are used to match the 29-bit identifier of extended frames.
-
Match-Standard-And-Extended: Bit 18 to 28 (11 bits) of filter mask and filter identifier are used to match the 11-bit identifier of standard frames, bit 0 to 17 (18 bits) are ignored in this case. Bit 0 to 28 (29 bits) of filter mask and filter identifier are used to match the 29-bit identifier of extended frames.
The filter mask and filter identifier are applied in this way: The filter mask is used to select the frame identifier bits that should be compared to the corresponding filter identifier bits. All unselected bits are automatically accepted. All selected bits have to match the filter identifier to be accepted. If all bits for the selected mode are accepted then the frame is accepted and is added to the read buffer.
"Filter Mask Bit", "Filter Identifier Bit", "Frame Identifier Bit", "Result" 0, X, X, Accept 1, 0, 0, Accept 1, 0, 1, Reject 1, 1, 0, Reject 1, 1, 1, Accept
For example, to receive standard frames with identifier 0x123 only, the mode can be set to Match-Standard-Only with 0x7FF as mask and 0x123 as identifier. The mask of 0x7FF selects all 11 identifier bits for matching so that the identifier has to be exactly 0x123 to be accepted.
To accept identifier 0x123 and identifier 0x456 at the same time, just set filter 2 to 0x456 and keep mask and filter 1 unchanged.
There can be up to 32 different read filters configured at the same time, because there can be up to 32 read buffer (see BrickletCANV2#set_queue_configuration
).
The default mode is accept-all for all read buffers.
# File lib/tinkerforge/bricklet_can_v2.rb, line 400 def set_read_filter_configuration(buffer_index, filter_mode, filter_mask, filter_identifier) check_validity send_request FUNCTION_SET_READ_FILTER_CONFIGURATION, [buffer_index, filter_mode, filter_mask, filter_identifier], 'C C L L', 8, '' end
Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.
You can also turn the LED permanently on/off or show a heartbeat.
If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.
# File lib/tinkerforge/bricklet_can_v2.rb, line 611 def set_status_led_config(config) check_validity send_request FUNCTION_SET_STATUS_LED_CONFIG, [config], 'C', 8, '' end
Sets the transceiver configuration for the CAN bus communication.
The CAN transceiver has three different modes:
-
Normal: Reads from and writes to the CAN bus and performs active bus error detection and acknowledgement.
-
Loopback: All reads and writes are performed internally. The transceiver is disconnected from the actual CAN bus.
-
Read-Only: Only reads from the CAN bus, but does neither active bus error detection nor acknowledgement. Only the receiving part of the transceiver is connected to the CAN bus.
# File lib/tinkerforge/bricklet_can_v2.rb, line 271 def set_transceiver_configuration(baud_rate, sample_point, transceiver_mode) check_validity send_request FUNCTION_SET_TRANSCEIVER_CONFIGURATION, [baud_rate, sample_point, transceiver_mode], 'L S C', 8, '' end
Sets the firmware pointer for BrickletCANV2#write_firmware
. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).
This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.
# File lib/tinkerforge/bricklet_can_v2.rb, line 584 def set_write_firmware_pointer(pointer) check_validity send_request FUNCTION_SET_WRITE_FIRMWARE_POINTER, [pointer], 'L', 8, '' end
Writes 64 Bytes of firmware at the position as written by BrickletCANV2#set_write_firmware_pointer
before. The firmware is written to flash every 4 chunks.
You can only write firmware in bootloader mode.
This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.
# File lib/tinkerforge/bricklet_can_v2.rb, line 598 def write_firmware(data) check_validity send_request FUNCTION_WRITE_FIRMWARE, [data], 'C64', 9, 'C' end
Writes a data or remote frame to the write queue to be transmitted over the CAN transceiver.
The Bricklet supports the standard 11-bit (CAN 2.0A) and the additional extended 29-bit (CAN 2.0B) identifiers. For standard frames the Bricklet uses bit 0 to 10 from the “identifier“ parameter as standard 11-bit identifier. For extended frames the Bricklet uses bit 0 to 28 from the “identifier“ parameter as extended 29-bit identifier.
The “data“ parameter can be up to 15 bytes long. For data frames up to 8 bytes will be used as the actual data. The length (DLC) field in the data or remote frame will be set to the actual length of the “data“ parameter. This allows to transmit data and remote frames with excess length. For remote frames only the length of the “data“ parameter is used. The actual “data“ bytes are ignored.
Returns true if the frame was successfully added to the write queue. Returns false if the frame could not be added because write queue is already full or because the write buffer or the write backlog are configured with a size of zero (see BrickletCANV2#set_queue_configuration
).
The write queue can overflow if frames are written to it at a higher rate than the Bricklet can transmitted them over the CAN transceiver. This may happen if the CAN transceiver is configured as read-only or is using a low baud rate (see BrickletCANV2#set_transceiver_configuration
). It can also happen if the CAN bus is congested and the frame cannot be transmitted because it constantly loses arbitration or because the CAN transceiver is currently disabled due to a high write error level (see BrickletCANV2#get_error_log
).
# File lib/tinkerforge/bricklet_can_v2.rb, line 709 def write_frame(frame_type, identifier, data) data = data.clone # clone so we can potentially extend it data_length = data.length data_data = data if data_length > 15 raise ArgumentError, 'Data can be at most 15 items long' end if data_length < 15 data_data += [0] * (15 - data_length) end write_frame_low_level frame_type, identifier, data_length, data_data end
Writes a data or remote frame to the write queue to be transmitted over the CAN transceiver.
The Bricklet supports the standard 11-bit (CAN 2.0A) and the additional extended 29-bit (CAN 2.0B) identifiers. For standard frames the Bricklet uses bit 0 to 10 from the “identifier“ parameter as standard 11-bit identifier. For extended frames the Bricklet uses bit 0 to 28 from the “identifier“ parameter as extended 29-bit identifier.
The “data“ parameter can be up to 15 bytes long. For data frames up to 8 bytes will be used as the actual data. The length (DLC) field in the data or remote frame will be set to the actual length of the “data“ parameter. This allows to transmit data and remote frames with excess length. For remote frames only the length of the “data“ parameter is used. The actual “data“ bytes are ignored.
Returns true if the frame was successfully added to the write queue. Returns false if the frame could not be added because write queue is already full or because the write buffer or the write backlog are configured with a size of zero (see BrickletCANV2#set_queue_configuration
).
The write queue can overflow if frames are written to it at a higher rate than the Bricklet can transmitted them over the CAN transceiver. This may happen if the CAN transceiver is configured as read-only or is using a low baud rate (see BrickletCANV2#set_transceiver_configuration
). It can also happen if the CAN bus is congested and the frame cannot be transmitted because it constantly loses arbitration or because the CAN transceiver is currently disabled due to a high write error level (see BrickletCANV2#get_error_log
).
# File lib/tinkerforge/bricklet_can_v2.rb, line 210 def write_frame_low_level(frame_type, identifier, data_length, data_data) check_validity send_request FUNCTION_WRITE_FRAME_LOW_LEVEL, [frame_type, identifier, data_length, data_data], 'C L C C15', 9, '?' end
Writes a new UID into flash. If you want to set a new UID you have to decode the Base58
encoded UID string into an integer first.
We recommend that you use Brick Viewer to change the UID.
# File lib/tinkerforge/bricklet_can_v2.rb, line 653 def write_uid(uid) check_validity send_request FUNCTION_WRITE_UID, [uid], 'L', 8, '' end