Hi guys,

OK, doing a dummy conversion on a floating input wasn't the greatest idea....

I took out the averaging and set up my arb gen to generate 3.3Vpp noise and injected that into AN1 (the dummy channel).

Code:

25.6mV input, 10k source resistor, 3.3V noise on "dummy channel":
FOSC/2 2 TAD Result: 512
FOSC/8 2 TAD Result: 120
FOSC/32 2 TAD Result: 23
FRC 2 TAD Result: 6
FOSC/4 2 TAD Result: 184
FOSC/16 2 TAD Result: 54
FOSC/64 2 TAD Result: 7
FOSC/2 4 TAD Result: 190
FOSC/8 4 TAD Result: 59
FOSC/32 4 TAD Result: 14
FRC 4 TAD Result: 13
FOSC/4 4 TAD Result: 117
FOSC/16 4 TAD Result: 21
FOSC/64 4 TAD Result: 14
FOSC/2 6 TAD Result: 127
FOSC/8 6 TAD Result: 32
FOSC/32 6 TAD Result: 11
FRC 6 TAD Result: 11
FOSC/4 6 TAD Result: 74
FOSC/16 6 TAD Result: 7
FOSC/64 6 TAD Result: 10
FOSC/2 8 TAD Result: 512
FOSC/8 8 TAD Result: 15
FOSC/32 8 TAD Result: 15
FRC 8 TAD Result: 12
FOSC/4 8 TAD Result: 56
FOSC/16 8 TAD Result: 10
FOSC/64 8 TAD Result: 6
FOSC/2 12 TAD Result: 512
FOSC/8 12 TAD Result: 11
FOSC/32 12 TAD Result: 16
FRC 12 TAD Result: 13
FOSC/4 12 TAD Result: 31
FOSC/16 12 TAD Result: 11
FOSC/64 12 TAD Result: 14
FOSC/2 16 TAD Result: 512
FOSC/8 16 TAD Result: 13
FOSC/32 16 TAD Result: 11
FRC 16 TAD Result: 11
FOSC/4 16 TAD Result: 18
FOSC/16 16 TAD Result: 11
FOSC/64 16 TAD Result: 9
FOSC/2 20 TAD Result: 49
FOSC/8 20 TAD Result: 15
FOSC/32 20 TAD Result: 10
FRC 20 TAD Result: 8
FOSC/4 20 TAD Result: 14
FOSC/16 20 TAD Result: 10
FOSC/64 20 TAD Result: 13
***************************************
3.285V, 10k source resistor 3.3V noise on "dummy channel":
FOSC/2 2 TAD Result: 511
FOSC/8 2 TAD Result: 861
FOSC/32 2 TAD Result: 1008
FRC 2 TAD Result: 1022
FOSC/4 2 TAD Result: 812
FOSC/16 2 TAD Result: 963
FOSC/64 2 TAD Result: 1014
FOSC/2 4 TAD Result: 511
FOSC/8 4 TAD Result: 964
FOSC/32 4 TAD Result: 1021
FRC 4 TAD Result: 1023
FOSC/4 4 TAD Result: 888
FOSC/16 4 TAD Result: 1004
FOSC/64 4 TAD Result: 1015
FOSC/2 6 TAD Result: 511
FOSC/8 6 TAD Result: 994
FOSC/32 6 TAD Result: 1019
FRC 6 TAD Result: 1023
FOSC/4 6 TAD Result: 911
FOSC/16 6 TAD Result: 1018
FOSC/64 6 TAD Result: 1019
FOSC/2 8 TAD Result: 511
FOSC/8 8 TAD Result: 1006
FOSC/32 8 TAD Result: 1019
FRC 8 TAD Result: 1021
FOSC/4 8 TAD Result: 964
FOSC/16 8 TAD Result: 1022
FOSC/64 8 TAD Result: 1016
FOSC/2 12 TAD Result: 511
FOSC/8 12 TAD Result: 1015
FOSC/32 12 TAD Result: 1019
FRC 12 TAD Result: 1019
FOSC/4 12 TAD Result: 991
FOSC/16 12 TAD Result: 1023
FOSC/64 12 TAD Result: 1015
FOSC/2 16 TAD Result: 511
FOSC/8 16 TAD Result: 1014
FOSC/32 16 TAD Result: 1018
FRC 16 TAD Result: 1018
FOSC/4 16 TAD Result: 1005
FOSC/16 16 TAD Result: 1016
FOSC/64 16 TAD Result: 1023
FOSC/2 20 TAD Result: 983
FOSC/8 20 TAD Result: 1020
FOSC/32 20 TAD Result: 1017
FRC 20 TAD Result: 1023
FOSC/4 20 TAD Result: 1010
FOSC/16 20 TAD Result: 1017
FOSC/64 20 TAD Result: 1019

Then I connected the dummy channel to GND:
Code:

25.6mV input, 10k source resistor, "dummy channel" connected to GND:
FOSC/2 2 TAD Result: 8
FOSC/8 2 TAD Result: 6
FOSC/32 2 TAD Result: 8
FRC 2 TAD Result: 7
FOSC/4 2 TAD Result: 6
FOSC/16 2 TAD Result: 7
FOSC/64 2 TAD Result: 7
FOSC/2 4 TAD Result: 8
FOSC/8 4 TAD Result: 7
FOSC/32 4 TAD Result: 8
FRC 4 TAD Result: 7
FOSC/4 4 TAD Result: 6
FOSC/16 4 TAD Result: 7
FOSC/64 4 TAD Result: 7
FOSC/2 6 TAD Result: 8
FOSC/8 6 TAD Result: 7
FOSC/32 6 TAD Result: 7
FRC 6 TAD Result: 7
FOSC/4 6 TAD Result: 6
FOSC/16 6 TAD Result: 7
FOSC/64 6 TAD Result: 7
FOSC/2 8 TAD Result: 8
FOSC/8 8 TAD Result: 7
FOSC/32 8 TAD Result: 7
FRC 8 TAD Result: 7
FOSC/4 8 TAD Result: 7
FOSC/16 8 TAD Result: 8
FOSC/64 8 TAD Result: 7
FOSC/2 12 TAD Result: 8
FOSC/8 12 TAD Result: 7
FOSC/32 12 TAD Result: 7
FRC 12 TAD Result: 7
FOSC/4 12 TAD Result: 8
FOSC/16 12 TAD Result: 7
FOSC/64 12 TAD Result: 7
FOSC/2 16 TAD Result: 8
FOSC/8 16 TAD Result: 7
FOSC/32 16 TAD Result: 7
FRC 16 TAD Result: 7
FOSC/4 16 TAD Result: 8
FOSC/16 16 TAD Result: 7
FOSC/64 16 TAD Result: 7
FOSC/2 20 TAD Result: 8
FOSC/8 20 TAD Result: 7
FOSC/32 20 TAD Result: 7
FRC 20 TAD Result: 7
FOSC/4 20 TAD Result: 8
FOSC/16 20 TAD Result: 8
FOSC/64 20 TAD Result: 7
*******************************************************
3.285V input, 10k source resistor, "dummy" channel connected to GND:
FOSC/2 2 TAD Result: 511
FOSC/8 2 TAD Result: 714
FOSC/32 2 TAD Result: 996
FRC 2 TAD Result: 1019
FOSC/4 2 TAD Result: 610
FOSC/16 2 TAD Result: 892
FOSC/64 2 TAD Result: 1018
FOSC/2 4 TAD Result: 511
FOSC/8 4 TAD Result: 862
FOSC/32 4 TAD Result: 1018
FRC 4 TAD Result: 1018
FOSC/4 4 TAD Result: 687
FOSC/16 4 TAD Result: 991
FOSC/64 4 TAD Result: 1019
FOSC/2 6 TAD Result: 511
FOSC/8 6 TAD Result: 955
FOSC/32 6 TAD Result: 1020
FRC 6 TAD Result: 1019
FOSC/4 6 TAD Result: 761
FOSC/16 6 TAD Result: 1010
FOSC/64 6 TAD Result: 1019
FOSC/2 8 TAD Result: 511
FOSC/8 8 TAD Result: 983
FOSC/32 8 TAD Result: 1020
FRC 8 TAD Result: 1018
FOSC/4 8 TAD Result: 836
FOSC/16 8 TAD Result: 1018
FOSC/64 8 TAD Result: 1019
FOSC/2 12 TAD Result: 511
FOSC/8 12 TAD Result: 1010
FOSC/32 12 TAD Result: 1020
FRC 12 TAD Result: 1019
FOSC/4 12 TAD Result: 944
FOSC/16 12 TAD Result: 1019
FOSC/64 12 TAD Result: 1020
FOSC/2 16 TAD Result: 511
FOSC/8 16 TAD Result: 1017
FOSC/32 16 TAD Result: 1019
FRC 16 TAD Result: 1018
FOSC/4 16 TAD Result: 981
FOSC/16 16 TAD Result: 1020
FOSC/64 16 TAD Result: 1019
FOSC/2 20 TAD Result: 511
FOSC/8 20 TAD Result: 1017
FOSC/32 20 TAD Result: 1019
FRC 20 TAD Result: 1019
FOSC/4 20 TAD Result: 998
FOSC/16 20 TAD Result: 1021
FOSC/64 20 TAD Result: 1020

And finally, dummy channel to Vdd (3.3V):
Code:

25.6mV input, 10k source resistor, "dummy channel" connected to Vdd:
FOSC/2 2 TAD Result: 512
FOSC/8 2 TAD Result: 344
FOSC/32 2 TAD Result: 29
FRC 2 TAD Result: 8
FOSC/4 2 TAD Result: 432
FOSC/16 2 TAD Result: 192
FOSC/64 2 TAD Result: 9
FOSC/2 4 TAD Result: 512
FOSC/8 4 TAD Result: 262
FOSC/32 4 TAD Result: 9
FRC 4 TAD Result: 8
FOSC/4 4 TAD Result: 383
FOSC/16 4 TAD Result: 46
FOSC/64 4 TAD Result: 8
FOSC/2 6 TAD Result: 512
FOSC/8 6 TAD Result: 180
FOSC/32 6 TAD Result: 8
FRC 6 TAD Result: 7
FOSC/4 6 TAD Result: 350
FOSC/16 6 TAD Result: 17
FOSC/64 6 TAD Result: 7
FOSC/2 8 TAD Result: 512
FOSC/8 8 TAD Result: 99
FOSC/32 8 TAD Result: 8
FRC 8 TAD Result: 7
FOSC/4 8 TAD Result: 312
FOSC/16 8 TAD Result: 10
FOSC/64 8 TAD Result: 7
FOSC/2 12 TAD Result: 512
FOSC/8 12 TAD Result: 25
FOSC/32 12 TAD Result: 7
FRC 12 TAD Result: 8
FOSC/4 12 TAD Result: 229
FOSC/16 12 TAD Result: 8
FOSC/64 12 TAD Result: 7
FOSC/2 16 TAD Result: 512
FOSC/8 16 TAD Result: 12
FOSC/32 16 TAD Result: 7
FRC 16 TAD Result: 8
FOSC/4 16 TAD Result: 147
FOSC/16 16 TAD Result: 7
FOSC/64 16 TAD Result: 7
FOSC/2 20 TAD Result: 512
FOSC/8 20 TAD Result: 9
FOSC/32 20 TAD Result: 7
FRC 20 TAD Result: 8
FOSC/4 20 TAD Result: 66
FOSC/16 20 TAD Result: 7
FOSC/64 20 TAD Result: 7
*********************************************
3.285V input, 10k source resistor, "dummy channel" connected to Vdd:
FOSC/2 2 TAD Result: 1022
FOSC/8 2 TAD Result: 1021
FOSC/32 2 TAD Result: 1020
FRC 2 TAD Result: 1020
FOSC/4 2 TAD Result: 1022
FOSC/16 2 TAD Result: 1020
FOSC/64 2 TAD Result: 1019
FOSC/2 4 TAD Result: 1022
FOSC/8 4 TAD Result: 1019
FOSC/32 4 TAD Result: 1019
FRC 4 TAD Result: 1019
FOSC/4 4 TAD Result: 1019
FOSC/16 4 TAD Result: 1021
FOSC/64 4 TAD Result: 1020
FOSC/2 6 TAD Result: 1023
FOSC/8 6 TAD Result: 1021
FOSC/32 6 TAD Result: 1019
FRC 6 TAD Result: 1020
FOSC/4 6 TAD Result: 1020
FOSC/16 6 TAD Result: 1020
FOSC/64 6 TAD Result: 1019
FOSC/2 8 TAD Result: 1022
FOSC/8 8 TAD Result: 1020
FOSC/32 8 TAD Result: 1019
FRC 8 TAD Result: 1019
FOSC/4 8 TAD Result: 1020
FOSC/16 8 TAD Result: 1021
FOSC/64 8 TAD Result: 1019
FOSC/2 12 TAD Result: 1022
FOSC/8 12 TAD Result: 1020
FOSC/32 12 TAD Result: 1019
FRC 12 TAD Result: 1020
FOSC/4 12 TAD Result: 1020
FOSC/16 12 TAD Result: 1021
FOSC/64 12 TAD Result: 1020
FOSC/2 16 TAD Result: 1021
FOSC/8 16 TAD Result: 1021
FOSC/32 16 TAD Result: 1019
FRC 16 TAD Result: 1021
FOSC/4 16 TAD Result: 1021
FOSC/16 16 TAD Result: 1019
FOSC/64 16 TAD Result: 1019
FOSC/2 20 TAD Result: 1020
FOSC/8 20 TAD Result: 1021
FOSC/32 20 TAD Result: 1019
FRC 20 TAD Result: 1021
FOSC/4 20 TAD Result: 1018
FOSC/16 20 TAD Result: 1019
FOSC/64 20 TAD Result: 1020

Henrik.

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