LAUNCHXL2-RM57L: reading external analog signal through ADC and printing the output in decimal

Apurv Mishra

Part Number: LAUNCHXL2-RM57L
Other Parts Discussed in Thread: HALCOGEN

Hey, everyone!

I am using RM57Lx LaunchPad. I need to read an external analog signal and get the outputs printed (using SCI) in decimal format.

The example code gives the channel ID and value in Hexadecimal which I do not need/wish.

Please, help!

Thanks,
Apurv

over 6 years ago

0 Sunil Oak over 6 years ago

TI__Mastermind 49120 points

Apurv,

The ADC returns a binary conversion result. The example code shows how to convert a binary number to a hexadecimal format in C code. This is just an example. You can write code to convert the binary conversion result to decimal format.

Regards,
Sunil

0 Apurv Mishra over 6 years ago in reply to Sunil Oak

Intellectual 750 points

Hey, Sunil!

Thank you for your help. Any example code for the conversion that you may provide?

Thanks,
Apurv

0 Apurv Mishra over 6 years ago in reply to Sunil Oak

Intellectual 750 points

One more thing, what ADC returns is the exact voltage value, right or do we have to map it or something?

0 Sunil Oak over 6 years ago in reply to Apurv Mishra

TI__Mastermind 49120 points

Apurv,

I do not have a code for conversion from binary to decimal, there are tons of resources to get an example online.

The ADC digital conversion value is referenced to the difference of ADREFhi and ADREFlo. The ADC chapter in the TRM has the equation that gives the digital value based on the input voltage.

0 Apurv Mishra over 6 years ago in reply to Sunil Oak

Intellectual 750 points

Hi, Sunil!

Thank you for being so helpful and prompt.

I needed one last help. I created a PWM signal on HET1[10] pin and got the ADC results for it but I actually need to read an external analog signal. I am attaching pictures of my ADC Group 1 HALCoGen configuration where I have enabled pin 7 and the pinout of RM57Lx board.
May you, please, confirm which should I connect the external signal to? I am connecting it to AD1[7] (as you can see in the pinout) as I have enabled pin 7 but I am getting no values.

Please help me with this, thank you!

Regards,
Apurv

0 Sunil Oak over 6 years ago in reply to Apurv Mishra

TI__Mastermind 49120 points

Do you want to use rising edge on HET1_10 to trigger the ADC conversions? The configuration shown in the figure you posted shows that a rising edge on AD1EVT is being used to trigger group1 conversions. Please change this to HET1_10 from the drop-down menu if you are generating a PWM on HET1_10.

0 Apurv Mishra over 6 years ago in reply to Sunil Oak

Intellectual 750 points

Hi!

I did PWM and it worked fine.

I actually need the ADC to work for an external signal. How do I do that? Also, mention, to which pin should I connect the external analog signal to.

Thanks,
Apurv

0 Sunil Oak over 6 years ago in reply to Apurv Mishra

TI__Mastermind 49120 points

The way you have the configuration done, the ADC1 will sample input channel AD1IN[7] whenever the ADC is triggered. Make sure that the correct trigger signal is selected via the drop-down in the "ADC1 Group1 Trigger" configuration in HALCoGen. The result is stored in the group1 FIFO. Do you see any results getting stored? Please read the ADC chapter of the RM57 TRM - spnu562a, section 22.2 starting on page 844.

0 Apurv Mishra over 6 years ago in reply to Sunil Oak

Intellectual 750 points

Thank you so much for such quick and 'precise' help :)

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LAUNCHXL2-RM57L: reading external analog signal through ADC and printing the output in decimal