AnalogIn test correction

[bcostm]

Change initial value of prev_value + do only one adc read.

Correction of Issue ARMmbed/mbed-os#2956

[BlackstoneEngineering]

@bcostm Wouldnt the simpler fix be just to initialize outputs and y to 1?

[pan-]

@BlackstoneEngineering I think the algorithm is done in the wrong order, it should be:

• Read the current voltage
• Enable one more pin
• Assert that the voltage is now more important than the previous value read.

it doesn't makes sense to assert that something is different if nothing has changed yet.

    for(x = 0; x<5; x++) {
        prev_value = ain.read();
        y = (y<<1) + 1;
        outputs = y;
        TEST_ASSERT_MESSAGE(ain.read() > prev_value,"Analog Input did not incriment. Check that you have assigned valid pins in mbed_app.json file")
    }

[BlackstoneEngineering]

@pan- Agreed.
@bcostm does vincents solution work for you on your platform? Will merge Vincents solution on Friday if I do not hear back from you before then

[bcostm]

Hi,
Yes I agree. Let me check and I come back to you.
So, yes this method works. I tested it on Nucleo_F429ZI only but I am confident...
How do you want to proceed ? I close this PR or I update it ?

[BlackstoneEngineering]

I will close the issue and update directly to master, i've already got a couple patches pending, I'll toss in this one line change.

Thanks all for the input and helping us build a better ecosystem!

[0xc0170]

@BlackstoneEngineering Whats the status of this PR? Can it be closed?

[BlackstoneEngineering]

@0xc0170 yeah, the changes have been mainlined already