MATLAB Code to Read Magnetic Field Sensor

$\%$ File to acquire live voltage data from analog port A$0.$

$\%$ If this produces an error, check the COM port number.

if not$($exist$(\text{'}$a$\text{'}))$

a$=$arduino;

end

N$=1000$; $\%$number of data points

figure; $\%$open a figure window

t$=$zeros$(1,$N$)$; $\%$preallocated memory for time array

B$=$zeros$(1,$N$)$; $\%$preallocated memory for B$-$field array

p$=$animatedline; $\%$create plot

xlabel$(\text{'}$time$($s$)\text{'})$; $\%$plot axis label

ylabel$(\text{'}$Magnetic Field$($G$)\text{'})$; $\%$plot axis label

Bbaseline $=$ a$.$readVoltage$("$A$0")$; $\%$Read baseline B field for comparison

t$0=$cputime; $\%$initial CPU time

$\%$loop to acquire real$-$time B$-$field for N iterations

for i$=1$:N

t$($i$)=$cputime$-$t$0$; $\%$update current time

B$($i$)=($a$.$readVoltage$("$A$0")-$Bbaseline$)/0\mathrm{.}0014$; $\%$update B$-$field array

addpoints$($p$,$ t$($i$),$B$($i$))$; $\%$add latest datum to plot

drawnow; $\%$draw updated plot

end

$1.$ Using your mini breadboard and jumper wires, you will connect three of the four pins on the sensor to the Arduino: G to GND$,+$ to $5$V and AO $($analog output$)$ to A$0$ or any other analog pin that you want to connect it to $($so long as the code expects data from that pin$).$

$2.$ Using the code above $($as an m$-$file in MATLAB$),$ read the highest and lowest values of magnetic field that you get when you place your magnet nearest the field sensor on your little chip $($the black protrusion at the top is the sensor$).$ Q$3$: What is the highest level in gauss $($G$)?$ Q$4$: What is the lowest? Q$5$: Are they roughly equal and opposite? HINT: Use max or min once you have a B array.