Rainbow Electronics DS1775R_T - Manual (Page 5)

DS1775
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O.S. OUTPUT TRANSFER FUNCTION Figure 2
Regardless of the mode chosen, the O.S. output is open–drain and the active state is set in the
configuration register. The power–up default is active low. Refer to the “OPERATION–Programming”
section for instructions in adjusting the thermostat setpoints, thermostat mode, and O.S. active state.
OPERATION–Programming
There are three areas of interest in programming the DS1775: the configuration register, the T
OS
register,
and the T
HYST
register. All programming is done via the 2–wire interface by setting the pointer to the
appropriate location. Table 3 illustrates the pointer settings for the four registers of the DS1775.
Pointer Register Structure Table 3
POINTER ACTIVE REGISTER
00h Temperature (default)
01h Configuration
02h T
HYST
03h T
OS
The DS1775 will power up with the temperature register selected. If the host wishes to change the data
pointer it simply addresses the DS1775 in the write mode (R/
W =0), receives an acknowledge, and writes
the 8 bits that correspond to the new desired location. The last pointer location is always maintained so
that consecutive reads from the same register do not require the host to always provide a pointer address.
The only exception is at power–up, in which case the pointer will always be set to 00h, the temperature