1-Wire Interfacing (1) Reset -- pull DQ low -- wait 500 uS (overdrive = ??? uS) -- release DQ (Hi-Z) -- wait 5 uS (overdrive = ??? uS) -- sample DQ; if low, line is shorted -- wait 70 uS (overdrive = ??? uS) -- sample for presence (should be 0) -- wait 150 uS {recovery} (overdrive = ??? uS) (2) Write 1 (slot time = ~70 uS) -- pull DQ low -- wait 5 uS (overdrive = ??? uS) -- release DQ (Hi-Z) -- wait 55 uS (overdrive = ??? uS) -- wait 10 uS? {recovery} (overdrive = ??? uS) (3) Write 0 (slot time = ~70 uS) -- pull DQ low -- wait 60 uS (overdrive = ??? uS) -- release DQ (Hi-Z) -- wait 10 uS {recovery} (overdrive = ??? uS) (4) Read Slot (critical timing) >> The 1-Wire device starts an internal timer on that falling edge and will place it's bit on the line 15 uS after the line falls >> If pull-down pulse is too narrow, the device may not respond properly. -- pull DQ low -- wait 5 uS <-- CRITICAL (overdrive = ??? uS) -- release DQ (Hi-Z) -- wait 10 uS (overdrive = ??? uS) -- sample DQ <-- timing CRITICAL -- wait 60 uS {recovery} (overdrive = ??? uS)