Add an option to pad outgoing CAN frames to 8 bytes (on by default).

Fixed #3.

2 files changed, 7 insertions, 1 deletions

diff --git a/src/uds/uds.c b/src/uds/uds.c
index f38c6aac..9fec9a88 100644
--- a/src/uds/uds.c
+++ b/src/uds/uds.c
@@ -87,6 +87,7 @@ DiagnosticRequestHandle diagnostic_request(DiagnosticShims* shims,
     handle.isotp_shims = isotp_init_shims(shims->log,
             shims->send_can_message,
             shims->set_timer);
+    handle.isotp_shims.frame_padding = !request->no_frame_padding;
 
     handle.isotp_send_handle = isotp_send(&handle.isotp_shims,
             request->arbitration_id, payload,
@@ -121,7 +122,7 @@ DiagnosticRequestHandle diagnostic_request(DiagnosticShims* shims,
     // that are just called continuously from the main loop. it's a waste of a
     // few cpu cycles but it may be more  natural than callbacks.
     //
-    // what woudl a timer callback look like...it would need to pass the handle
+    // what would a timer callback look like...it would need to pass the handle
     // and that's all. seems like a context void* would be able to capture all
     // of the information but arg, memory allocation. look at how it's done in
     // the other library again
diff --git a/src/uds/uds_types.h b/src/uds/uds_types.h
index 88c7ce44..10d15d62 100644
--- a/src/uds/uds_types.h
+++ b/src/uds/uds_types.h
@@ -42,6 +42,10 @@ typedef enum {
  * payload - (optional) The payload for the request, if the request requires
  *      one. If payload_length is 0 this field is ignored.
  * payload_length - The length of the payload, or 0 if no payload is used.
+ * no_frame_padding - false if sent CAN payloads should *not* be padded out to a
+ *      full 8 byte CAN frame. Many ECUs require this, but others require the
+ *      size of the CAN message to only be the actual data. By default padding
+ *      is enabled (so this struct value can default to 0).
  * type - the type of the request (TODO unused)
  */
 typedef struct {
@@ -52,6 +56,7 @@ typedef struct {
     uint8_t pid_length;
     uint8_t payload[MAX_UDS_PAYLOAD_LENGTH];
     uint8_t payload_length;
+    bool no_frame_padding;
     DiagnosticRequestType type;
 } DiagnosticRequest;