A four point measurement technique for testing programmable impedance drivers such as the BZIO buffers contained in RapidChip\xae and ASIC devices. The method includes, while keeping an idle state without confirming the existence or non-existence of downlink data, determining to transit into a wakeup state, performing signaling for the transition into the wakeup state, acquiring information on discarded downlink data transmission through the signaling, and receiving the downlink data using the information on the downlink data transmission. Accordingly, by parallely performing the method for inducing a merge candidate, parallel processing is enabled and the computation amount and implementation complexity are reduced. The stop limits the penetration depth of the tip into a cornea.