+SOFTWAREACK_TIMEOUT:
+
+The number of microseconds the driver should wait for a software
+acknowledgement on the sender side. If your SPI bus is slow, then it will
+take more time to download and upload the message from/to the radio chip,
+so you need to increase this wait period. For example, for IRIS->IRIS
+communication 800 microsec is enough, but for IRIS->TELOS we need 1600
+because the TELOS in software ack mode is slow to reply with an ack packet.