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| -rw-r--r-- | readme.rst | 21 |
1 files changed, 14 insertions, 7 deletions
@@ -11,12 +11,13 @@ Max Staudt <max-linux@enpas.org> Motivation ----------- -CAN adapters are expensive, few, and far between. -ELM327 interfaces are cheap and plentiful. - This driver aims to lower the initial cost for hackers interested in working with CAN buses. +CAN adapters are expensive, few, and far between. +ELM327 interfaces are cheap and plentiful. +Let's use ELM327s as CAN adapters. + Introduction @@ -27,7 +28,7 @@ into full-fledged (as far as possible) CAN interfaces. Since the ELM327 was never meant to be a stand-alone CAN controller, the driver has to switch between its modes as quickly as possible in -order to approximate full-duplex operation. +order to fake full-duplex operation. As such, elmcan is a best-effort driver. However, this is more than enough to implement simple request-response protocols (such as OBD II), @@ -67,6 +68,7 @@ How to check the controller version ------------------------------------ Use a terminal program to attach to the controller. +The default settings are 38400 baud/s, 8 data bits, no parity, 1 stopbit. After issuing the "``AT WS``" command, the controller will respond with its version:: @@ -78,6 +80,9 @@ its version:: > +Note that clones may claim to be any version they like. +It is not indicative of their actual feature set. + How to attach the line discipline @@ -111,6 +116,8 @@ Module parameters Some adapters and/or their connection are unreliable. Enable this option to try and work around the situation. This is a best-effort workaround, so undefined behavior will likely occur sooner or later. + Without this option, the driver will bail on the first unrecognized + character it receives from the TTY. LOAD TIME:: @@ -121,7 +128,7 @@ Module parameters Known limitations of the controller ------------------------------------ -- Clone "v1.5" devices +- Clone devices ("v1.5" and others) Sending RTR frames is not supported and will be dropped silently. @@ -139,8 +146,8 @@ Known limitations of the controller - All versions - No automatic full duplex operation is supported. The driver will - switch between input/output mode as quickly as possible. + No full duplex operation is supported. The driver will switch + between input/output mode as quickly as possible. The length of outgoing RTR frames cannot be set. In fact, some clones (tested with one identifying as "``v1.5``") are unable to |