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SFR explanation for PIC16F628(6)

VRCON ( Voltage Reference Control Register ) 9Fh This register controls Voltage Reference function. The value in the parenthesis is in the condition immediately after the turning on. VREN : VREF Enable 1 : VREF circuit powered on 0 : VREF circuit powered down, no IDD drain VRON : VREF Output Enable 1 : VREF is output on RA2 pin 0 : VREF is disconnected from RA2 pin VRR : VREF Range selection 1 : Low Range 0 : High Range VR3-0 : VREF value selection 0 =< VR [3:0] >= 15 When VRR = 1 (Low Range) VREF = (VR<3:0>/ 24) * VDD When VRR = 0 (High Range) VREF = 1/4 * VDD + (VR<3:0>/ 32) * VDD Resistance and Voltage Relationship in case of VDD = 5V VR3-0 Low Range High Range 0000 0.00 1.25 0001 0.21 1.41 0010 0.42 1.56 0011 0.63 1.72 0100 0.83 1.88 0101 1.04 2.03 0110 1.25 2.19 0111 1.46 2.34 VR3-0 Low Rabge High Range 1000 1.67 2.50 1001 1.88 2.66 1010 2.08 2.81 1011 2.29 2.97 1100 2.50 3.13 1101 2.71 3.28 1110 2.92 3.44 1111 3.13 3.59