Rainbow Electronics DS1841 - Manual (Page 11)

DS1841
Temperature-Controlled, NV, I 2 C,
Logarithmic Resistor
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Register 03h: Control Register 1 (CR1)
FACTORY DEFAULT 00h
MEMORY TYPE Shadowed NV
03h Reserved Reserved Reserved Reserved Reserved Reserved Adder Mode Update Mode
Bit 7 Bit 0
Bits 7 to 2 Reserved.
Bit 1
Adder Mode This bit is valid only if the Update Mode bit = 1.
0 = (Default) The LUTVAL or IVR value is directly loaded to WR though the mux.
1 = The LUTVAL is summed with the IVR value and is directly loaded to WR though the mux.
Bit 0
Update Mode
0 = (Default) CR0 is enabled. During power-up the IVR value is loaded into the WR to set the wiper
position. Updates to Temperature Result (0Ch) and Supply Voltage Result (0Eh) are halted.
1 = The WR is controlled directly by I
2 C communication though registers 08h or 09h, or the WR is
controlled by the temperature-compensation/LUT circuitry. If temperature compensation is enabled, one
of the 72 temperature slots is selected (by the LUTAR) and this slot value is copied into the LUTVAL,
which in turn sets the WR. Updates to Temperature Result (0Ch) and Supply Voltage Result (0Eh) are
enabled.
Control Register 1 controls how the wiper position is determined. The SEE bit controls whether the values of this register
are stored in EEPROM or in Shadowed SRAM. On power-up, the EEPROM value is recalled to this register, regardless of
the state of
SEE.
While the registers other than 00h through 0Ah can be read, they are not updated by the ADC as the ADC is disabled
with the Update Mode bit = 0.
Register 08h: LUT Address Register (LUTAR)
FACTORY DEFAULT 00h
POR DEFAULT 00h until t FRAME
MEMORY TYPE Volatile
08h LUTAR
Bit 7 Bit 0
The LUTAR register serves as the index pointer to choose the corresponding temperature slot in the LUT based on the
internal temperature sensor result. The LUTAR can be directly read by acessing address 08h; however, to write an new
value to LUTAR (to control WR manually), the LUTAR Mode bit must be set to a 1.
Register 09h: LUT Value Register (WR*)
FACTORY DEFAULT 00h
MEMORY TYPE Volatile
09h WR*
Bit 7 Bit 0
WR serves as an intermediate location, which is populated automatically with the results of the temperature-indexed
lookup. The WR can be directly read by acessing address 09h; however to write an new value to WR (to control it
manually), the wiper access control bit must be set to a 1. WR is an unsigned 7-bit value.
*WR is updated every t FRAME if Update Mode bit = 1. If Update Mode bit = 0, WR holds the value stored in register 00h.