X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=README.md;h=ba1641929e0047a0872bb460dc11a66c986a5d83;hb=6f4799ca62b964e5626d9b22c4d292e6bd378d57;hp=30720db54e04d9f044143ea44671027659d03d88;hpb=2e14ec89c5fb2e3c0d4ed4bcde5e7b04443f0413;p=apps%2Fagl-service-can-low-level.git

diff --git a/README.md b/README.md
index 30720db5..ba164192 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,127 @@ The expected format of an event message is:
 This format is good for something like a button event, where there are two
 discrete pieces of information in the measurement.
 
+## Raw CAN Message format
+
+An OpenXC vehicle interface may also output raw CAN messages. Each CAN message
+is sent as a JSON object, separated by newlines. The format of each object is:
+
+    {"bus": 1, "id": 1234, "value": "0x12345678"}
+
+**bus** - the numerical identifier of the CAN bus where this message originated,
+  most likely 1 or 2 (for a vehicle interface with 2 CAN controllers).
+
+**id** - the CAN message ID
+
+**data** - up to 8 bytes of data from the CAN message's payload, represented as
+  a hexidecimal number in a string. Many JSON parser cannot handle 64-bit
+  integers, which is why we are not using a numerical data type.
+
+## Diagnostic Messages
+
+### Requests
+
+    {"bus": 1,
+      "id": 1234,
+      "mode": 1,
+      "pid": 5,
+      "payload": "0x1234",
+      "frequency": 0}
+
+**bus** - the numerical identifier of the CAN bus where this request should be
+    sent, most likely 1 or 2 (for a vehicle interface with 2 CAN controllers).
+
+**id** - the CAN arbitration ID for the request.
+
+**mode** - the OBD-II mode of the request - 0x1 through 0xf (0x1 through 0xa
+    are the standardized modes).
+
+**pid** - (optional) the PID for the request, if applicable.
+
+**payload** - (optional) up to 7 bytes of data for the request's payload
+    represented as a hexidecimal number in a string. Many JSON parser cannot
+    handle 64-bit integers, which is why we are not using a numerical data type.
+
+**frequency** - (optional, defaults to 0) The frequency in Hz to send this
+    request. To send a single request, set this to 0 or leave it out.
+
+TODO it'd be nice to have the OBD-II PIDs built in, with the proper conversion
+functions - that may need a different output format
+
+If you're just requesting a PID, you can use a simplified format for the
+request:
+
+    {"bus": 1, "id": 1234, "mode": 1, "pid": 5}
+
+### Responses
+
+    {"bus": 1,
+      "id": 1234,
+      "mode": 1,
+      "pid": 5,
+      "success": true,
+      "negative_response_code": 17,
+      "payload": "0x1234"}
+
+**bus** - the numerical identifier of the CAN bus where this response was
+    received.
+
+**id** - the CAN arbitration ID for this response.
+
+**mode** - the OBD-II mode of the original diagnostic request.
+
+**pid** - (optional) the PID for the request, if applicable.
+
+**success** -  true if the response received was a positive response. If this
+  field is false, the remote node returned an error and the
+  `negative_response_code` field should be populated.
+
+**negative_response_code** - (optional)  If requsted node returned an error,
+    `success` will be `false` and this field will contain the negative response
+    code (NRC).
+
+**payload** - (optional) up to 7 bytes of data returned in the response,
+    represented as a hexidecimal number in a string. Many JSON parser cannot
+    handle 64-bit integers, which is why we are not using a numerical data type.
+
+The response to a simple PID requset would look like this:
+
+    {"bus": 1, "id": 1234, "mode": 1, "pid": 5, "payload": "0x2"}
+
+TODO again, it'd be nice to have the OBD-II PIDs built in, with the proper
+conversion functions so the response here included the actual transformed value
+of the pid and a human readable name
+
+## Trace File Format
+
+An OpenXC vehicle trace file is a plaintext file that contains JSON objects,
+separated by newlines.
+
+The first line may be a metadata object, although this is optional:
+
+```
+{"metadata": {
+    "version": "v3.0",
+    "vehicle_interface_id": "7ABF",
+    "vehicle": {
+        "make": "Ford",
+        "model": "Mustang",
+        "trim": "V6 Premium",
+        "year": 2013
+    },
+    "description": "highway drive to work",
+    "driver_name": "TJ Giuli",
+    "vehicle_id": "17N1039247929"
+}
+```
+
+The following lines are OpenXC messages with a `timestamp` field added, e.g.:
+
+    {"timestamp": 1385133351.285525, "name": "steering_wheel_angle", "value": 45}
+
+The timestamp is in [UNIX time](http://en.wikipedia.org/wiki/Unix_time)
+(i.e. seconds since the UNIX epoch, 00:00:00 UTC, 1/1/1970).
+
 ## Official Signals
 
 These signal names are a part of the OpenXC specification, although some
@@ -96,22 +217,6 @@ manufacturers may support custom message names.
     * numerical, -179.0 to 179.0 degrees with standard GPS accuracy
     * 1Hz
 
-## Raw CAN Message format
-
-An OpenXC vehicle interface may also output raw CAN messages. Each CAN message
-is sent as a JSON object, separated by newlines. The format of each object is:
-
-    {"bus": 1, "id": 1234, "value": "0x12345678"}
-
-**bus** - the numerical identifier of the CAN bus where this message originated,
-  most likely 1 or 2 (for a vehicle interface with 2 CAN controllers).
-
-**id** - the CAN message ID
-
-**data** - up to 8 bytes of data from the CAN message's payload, represented as
-  a hexidecimal number in a string. Many JSON parser cannot handle 64-bit
-  integers, which is why we are not using a numerical data type.
-
 License
 =======