+How to check the controller version
+------------------------------------
+
+Use a terminal program to attach to the controller.
+
+After issuing the "``AT WS``" command, the controller will respond with
+its version::
+
+ >AT WS
+
+
+ ELM327 v1.4b
+
+ >
+
+Note that clones may claim to be any version they like.
+It is not indicative of their actual feature set.
+
+
+
+
+Communication example
+----------------------
+
+This is a short and incomplete introduction on how to talk to an ELM327.
+It is here to guide understanding of the controller's and the driver's
+limitation (listed below) as well as manual testing.
+
+
+The ELM327 has two modes:
+
+- Command mode
+- Reception mode
+
+In command mode, it expects one command per line, terminated by CR.
+By default, the prompt is a "``>``", after which a command can be
+entered::
+
+ >ATE1
+ OK
+ >
+
+The init script in the driver switches off several configuration options
+that are only meaningful in the original OBD scenario the chip is meant
+for, and are actually a hindrance for can327.
+
+
+When a command is not recognized, such as by an older version of the
+ELM327, a question mark is printed as a response instead of OK::
+
+ >ATUNKNOWN
+ ?
+ >
+
+At present, can327 does not evaluate this response and silently assumes
+that all commands are recognized. It is structured such that it will
+degrade gracefully when a command is unknown. See the sections above on
+known limitations for details.
+
+
+When a CAN frame is to be sent, the target address is configured, after
+which the frame is sent as a command that consists of the data's hex
+dump::
+
+ >ATSH123
+ OK
+ >DEADBEEF12345678
+ OK
+ >
+
+The above interaction sends the SFF frame "``DE AD BE EF 12 34 56 78``"
+with (11 bit) CAN ID ``0x123``.
+For this to function, the controller must be configured for SFF sending
+mode (using "``AT PB``", see code or datasheet).
+
+
+Once a frame has been sent and wait-for-reply mode is on (``ATR1``,
+configured on ``listen-only=off``), or when the reply timeout expires
+and the driver sets the controller into monitoring mode (``ATMA``),
+the ELM327 will send one line for each received CAN frame, consisting
+of CAN ID, DLC, and data::
+
+ 123 8 DEADBEEF12345678
+
+For EFF (29 bit) CAN frames, the address format is slightly different,
+which can327 uses to tell the two apart::
+
+ 12 34 56 78 8 DEADBEEF12345678
+
+The ELM327 will receive both SFF and EFF frames - the current CAN
+config (``ATPB``) does not matter.
+
+
+If the ELM327's internal UART sending buffer runs full, it will abort
+the monitoring mode, print "BUFFER FULL" and drop back into command
+mode. Note that in this case, unlike with other error messages, the
+error message may appear on the same line as the last (usually
+incomplete) data frame::
+
+ 12 34 56 78 8 DEADBEEF123 BUFFER FULL
+
+
+