Reading digital inputs with TMS320F2812

Jonas 67

Other Parts Discussed in Thread: TMS320F2812

Hello

I have a question about receving digital inputs using TMS320F2812. i have a digital unit which is giving digital outputs (0-3.3 volts PWM squarewave) which is being fed into the DSP. My question is, how can I read/retrieve/get a specific value, For example;

0,2 volt = 2

0,8 volt = 8

1 volt = 10

(...)

3 volt = 30

I have looked in the "C281x C/C++ Header Files and Peripheral Examples", but I could not find anything directly related to my problem.

A small code example would be very helpful.

Best regards Jonas

over 13 years ago

0 Jonas 67 over 13 years ago

Prodigy 70 points

I will try to elaborate. What I think I need to do is set an 'acquisition time', meaning a time period where I can receive a set of PWM input voltages giving me a digital value (a number of bits) for the DSP. This time period then has to be set up again to recevie a new set of inputs. I think I have to use a timer for this, but I am not sure.

0 Frank Bormann over 13 years ago in reply to Jonas 67

Mastermind 7585 points

If I understand your request right, then all you need to do is to use an ADC. It purpose is to translate voltages into numbers. If your intention is to measure the PWM ratio high-low, then a Capture unit will do the job.

0 Jonas 67 over 13 years ago in reply to Frank Bormann

Prodigy 70 points

I am not using ADC since the signals coming from the unit are already digital. Using Capture unit is a preferable method, thank you. I am not sure how to set up the registers for using DSP Capture unit (I am using CCS v.4). Are there any examples available on how to set up Capture unit in connection with external hardware input?

0 Jonas 67 over 13 years ago in reply to Jonas 67

Prodigy 70 points

Thanks for the guidelines. I will keep the Capture approach in mind, but give this a try with the ADC now. I have made a new post about the relevant issues.

http://e2e.ti.com/support/microcontrollers/tms320c2000_32-bit_real-time_mcus/f/172/t/104479.aspx

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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Reading digital inputs with TMS320F2812