From 104e08ea708ea3e706c49d0699eaf1bac103a486 Mon Sep 17 00:00:00 2001 From: Nick Elmschig Date: Mon, 22 Oct 2018 12:50:24 -0700 Subject: [PATCH] Add documentation on the CAN filter value, must include CAN_EFF_FLAG --- candump.c | 1 + 1 file changed, 1 insertion(+) diff --git a/candump.c b/candump.c index f98d1c3..98f28b8 100644 --- a/candump.c +++ b/candump.c @@ -147,6 +147,7 @@ void print_usage(char *prg) fprintf(stderr, "\nCAN IDs, masks and data content are given and expected in hexadecimal values.\n"); fprintf(stderr, "When can_id and can_mask are both 8 digits, they are assumed to be 29 bit EFF.\n"); fprintf(stderr, "Without any given filter all data frames are received ('0:0' default filter).\n"); + fprintf(stderr, "The filter value is directly passed to the SocketCAN interface, and must set CAN_EFF_FLAG (0x80000000) correctly."); fprintf(stderr, "\nUse interface name '%s' to receive from all CAN interfaces.\n", ANYDEV); fprintf(stderr, "\nExamples:\n"); fprintf(stderr, "%s -c -c -ta can0,123:7FF,400:700,#000000FF can2,400~7F0 can3 can8\n", prg);