Clarify when we are using int vs float and move decoders up a level.

[apps/low-level-can-service.git] / README.mkd

diff --git a/README.mkd b/README.mkd
index 041eff4..8f9574f 100644 (file)
--- a/README.mkd
+++ b/README.mkd
@@ -1,9 +1,11 @@
-OBD-II Support Library in C
-=============================
+Unified Diagnostic Services (UDS) Support Library in C
+======================================================
 
-This is a platform agnostic C library that implements the standard On Board
-Diagnostics system for vehicles. It currently supports OBD-II running over CAN
-(ISO 15765-4), which uses the ISO-TP (ISO 15765-2) protocol underneath.
+This is a platform agnostic C library that implements the Unified Diagnostics
+Services protocol for automotive electronics. UDS is documented in ISO 14229 and
+is the underpinning for the more well-known On-board Diagnostics (OBD) standard.
+The library currently supports UDS running over CAN (ISO 15765-4), which uses
+the ISO-TP (ISO 15765-2) protocol for message framing.
 
 This library doesn't assume anything about the source of your diagnostic message
 requests or underlying interface to the CAN bus. It uses dependency injection to
@@ -17,7 +19,7 @@ system:
     // required, this must send a single CAN message with the given arbitration
     // ID (i.e. the CAN message ID) and data. The size will never be more than 8
     // bytes.
-    void send_can(const uint16_t arbitration_id, const uint8_t* data,
+    bool send_can(const uint16_t arbitration_id, const uint8_t* data,
             const uint8_t size) {
         ...
     }
@@ -37,8 +39,8 @@ With your shims in place, create a `DiagnosticShims` object to pass them around:
 
     DiagnosticShims shims = diagnostic_init_shims(debug, send_can, set_timer);
 
-With your shims in hand, send a simple PID request to the stadnard broadcast
-address, `0x7df`:
+With your shims in hand, send a simple PID request to the standard broadcast
+address, `0x7df` (we use the constant `OBD2_FUNCTIONAL_BROADCAST_ID` here):
 
     // Optional: This is your callback that will be called the response to your
     // diagnostic request is received.
@@ -48,7 +50,7 @@ address, `0x7df`:
 
     DiagnosticRequestHandle handle = diagnostic_request_pid(&shims,
             DIAGNOSTIC_STANDARD_PID, // this is a standard PID request, not an extended or enhanced one
-            0x7df, // the request is going out to the broadcast arbitration ID
+            OBD2_FUNCTIONAL_BROADCAST_ID, // the request is going out to the broadcast arbitration ID
             0x2, // we want PID 0x2
             response_received_handler); // our callback (optional, use NULL if you don't have one)
 
@@ -97,7 +99,7 @@ If you want to do more besides PID requests on mode 0x1 and 0x22, there's a
 lower level API you can use. Here's how to make a mode 3 request to get DTCs.
 
     DiagnosticRequest request = {
-        arbitration_id: 0x7df,
+        arbitration_id: OBD2_FUNCTIONAL_BROADCAST_ID,
         mode: OBD2_MODE_EMISSIONS_DTC_REQUEST
     };
     DiagnosticRequestHandle handle = diagnostic_request(&SHIMS, &request, NULL);