Two things.

First of all, the "--bmsc-options 115200:20 " is MANDATORY.  I was not using it and having it on the command line made all the difference in the world.

Next, what processor / OS are you running?  i.e. does "uname -p" say  "i386" or "x86_64"?

The same exact sequence on an intel i3 running ubuntu 12.04 x86_64 gives a compiler warning that it will crash because of a memory overflow and really does.  Fixing the memcpy from trying to copy 5 bytes into a 4 byte uint32 stops the crash and lets the program run.  Your compiler / OS / processor may be more forgiving of the driver trying to stuff 5 bytes into a 4 bytes entity.

FWIW, what I did to make it work on an i3 running ubuntu 12.04 was

--- a/driver-bmsc.c
+++ b/driver-bmsc.c
@@ -1276,7 +1276,7 @@ static int64_t bmsc_scanwork(struct thr_info *thr)
                goto out;
        }

-       memcpy((char *)&nonce, nonce_bin, sizeof(nonce_bin));
+       memcpy((char *)&nonce, nonce_bin, sizeof(nonce));
        nonce = htobe32(nonce);
        curr_hw_errors = bmsc->hw_errors;
        submit_nonce(thr, work, nonce);

which is essentially to only copy 4 of the 5 bytes returned by the driver before the byte swap.  Only 4 bytes are used by the code so this is a safe change.