Add PX4IO voltage dataset and linear fit

Tools/tests-host/data/fit_linear_voltage.m

@@ -0,0 +1,14 @@
+close all;
+clear all;
+M = importdata('px4io_v1.3.csv');
+voltage = M.data(:, 1);
+counts = M.data(:, 2);
+plot(counts, voltage, 'b*-', 'LineWidth', 2, 'MarkerSize', 15);
+coeffs = polyfit(counts, voltage, 1);
+fittedC = linspace(min(counts), max(counts), 500);
+fittedV = polyval(coeffs, fittedC);
+hold on
+plot(fittedC, fittedV, 'r-', 'LineWidth', 3);
+
+slope = coeffs(1)
+y_intersection = coeffs(2)

Tools/tests-host/data/px4io_v1.3.csv

@@ -0,0 +1,70 @@
+voltage, counts
+4.3, 950
+4.4, 964
+4.5, 986
+4.6, 1009
+4.7, 1032
+4.8, 1055
+4.9, 1078
+5.0, 1101
+5.2, 1124
+5.3, 1148
+5.4, 1171
+5.5, 1195
+6.0, 1304
+6.1, 1329
+6.2, 1352
+7.0, 1517
+7.1, 1540
+7.2, 1564
+7.3, 1585
+7.4, 1610
+7.5, 1636
+8.0, 1728
+8.1, 1752
+8.2, 1755
+8.3, 1798
+8.4, 1821
+9.0, 1963
+9.1, 1987
+9.3, 2010
+9.4, 2033
+10.0, 2174
+10.1, 2198
+10.2, 2221
+10.3, 2245
+10.4, 2268
+11.0, 2385
+11.1, 2409
+11.2, 2432
+11.3, 2456
+11.4, 2480
+11.5, 2502
+11.6, 2526
+11.7, 2550
+11.8, 2573
+11.9, 2597
+12.0, 2621
+12.1, 2644
+12.3, 2668
+12.4, 2692
+12.5, 2716
+12.6, 2737
+12.7, 2761
+13.0, 2832
+13.5, 2950
+13.6, 2973
+14.1, 3068
+14.2, 3091
+14.7, 3209
+15.0, 3280
+15.1, 3304
+15.5, 3374
+15.6, 3397
+15.7, 3420
+16.0, 3492
+16.1, 3514
+16.2, 3538
+16.9, 3680
+17.0, 3704
+17.1, 3728