device_drivers/can/can327.rst

1 .. SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
7 --------
14 -----------
26 -------------
29 into full fledged (as far as possible) CAN interfaces.
33 order to fake full-duplex operation.
36 enough to implement simple request-response protocols (such as OBD II),
50 -----------
59 ----------------------------------
68            --debug \
69            --speed 38400 \
70            --eightbits \
71            --noparity \
72            --onestopbit \
73            --iflag -ICRNL,INLCR,-IXOFF \
88 500000 bit/s is a common rate for OBD-II diagnostics.
97 ------------------------------------
118 ----------------------
127 - Command mode
128 - Reception mode
154 When a CAN frame is to be sent, the target address is configured, after
155 which the frame is sent as a command that consists of the data's hex
164 The above interaction sends the SFF frame "``DE AD BE EF 12 34 56 78``"
170 Once a frame has been sent and wait-for-reply mode is on (``ATR1``,
171 configured on ``listen-only=off``), or when the reply timeout expires
173 the ELM327 will send one line for each received CAN frame, consisting
183 The ELM327 will receive both SFF and EFF frames - the current CAN
187 If the ELM327's internal UART sending buffer runs full, it will abort
188 the monitoring mode, print "BUFFER FULL" and drop back into command
191 incomplete) data frame::
193     12 34 56 78 8 DEADBEEF123 BUFFER FULL
198 ------------------------------------
200 - Clone devices ("v1.5" and others)
204   Receiving RTR with DLC 8 will appear to be a regular frame with
205   the last received frame's DLC and payload.
210   However, immediately after sending a frame, the ELM327 will be in
212   Once the bus goes silent, or an error occurs (such as BUFFER FULL),
221 - All versions
223   No full duplex operation is supported. The driver will switch
230   We don't have a way to get real-time notifications on CAN errors.
235 - Versions prior to 1.4b
239   after sending a frame. The driver maximizes this time to make the
243   command, and the "listen-only" CAN option will take effect.
246 - Versions prior to 1.4
249   change bitrate or SFF/EFF mode on-the-fly. This will have to be
254 - Versions prior to 1.3
258   on incoming data, as well as distinction of RTR frame lengths.
270 --------------------------------
272 - No 8/7 timing.
280 - No evaluation of command responses.
288 - No use of hardware CAN ID filtering
291   load, resulting in the "``BUFFER FULL``" message. Using the hardware
299 ------------------------------------------
314   the host (BUFFER FULL).
324 ------------------------------
327 the bus. This is correct when it is plugged into a OBD-II socket, but