Only trigger the Error behaviour on the mandatory events

The automatic NMT transition to Pre-operational, or any other action
that has been configured in 1029h, is only required to happen on Bus-
off or Life guarding/Heartbeat time-out. Currently, all EMCYs that are
sent do trigger the error behaviour, even if the error is not a
"serious CANopen device failure". It even reverts back to pre-operational
when an error is cleared and EMCY 0x0000 is sent.

Turn off the error behaviour except for EMCY codes 0x8130 and 0x8140
which correspond to the mandatory events (although the Bus-off EMCY
actually means *recovery* from Bus-off, so the Error behavior will
happen much later than was probably intended).

Ref: #39
Change-Id: I09cc847f6dc2bcc2e32411625c33d7fe2dce2368

Author: nattgris

src/co_emcy.c

@@ -257,6 +257,10 @@ int co_emcy_tx (co_net_t * net, uint16_t code, uint16_t info, uint8_t msef[5])
       net->cb_emcy (net->cb_arg, net->node, code, reg, msef);
    }
 
+   if (code != 0x8140 && code != 0x8130) {
+      return 0;
+   }
+
    /* Transition state according to error behavior setting */
    switch (net->error_behavior)
    {