Fix AvalonSTPkts _send_string
As pointed out by issue the ping tun tap example crashes, because a write
is attempted during a read-only phase. This fix was inspired by the discussion
on issue It waits for the NExtTimeStep before driving default values on the
bus in AvalonSTPkts::_send_string
@@ -573,6 +573,7 @@ class AvalonSTPkts(ValidatedBusDriver):
# Drive some defaults since we don't know what state we're in
# self.bus.empty <= 0
+ yield NextTimeStep()
self.bus.startofpacket <= 0
self.bus.endofpacket <= 0
self.bus.valid <= 0
