Repeating table driven wave form on Piccolo MCU

Altair Forum User

Submitted by Joe on Thu, 02/07/2013 - 23:47 

 

 

Hi, I am using Vissim ECD and F28027. I want to output a repeating waveform which will has 720 values of pressure. Is i possible to use DAC and output a waveform using Vissim and launchpad F28027. If yes can you please point towards an example.

Altair Forum User

Submitted by Rich on Fri, 02/08/2013 - 00:01.

The attached diagram samples at 100Hz and repeats your mapped signal at 1 Hz. To change the frequency, right click the ramp block and choose a different ramp frequency. Note that the system frequency should be about 100 x faster than the ramp frequency so you get a smooth waveform. Note that the table lookup map block will automatically convert to fixed point if you connect a fixed-point scaled value to the input. The generated lookup code will perform interpolation and automatically scale output radix point for maximum precision.
There is no DAC on the F28027, so you can use the PWM output. If you are driving a load with some inductance or capacitance, you should get a proportional voltage response similar to a DAC with sufficient switching frequency. You can compile it for debug mode or standalone. For standalone just don’t check the “Include VisSim Communication” box. Also, the table itself takes too much memory to fit in RAM on the F28027, so you must target flash and burn the .out file to flash before it will run properly. We recommend using TI Uniflash for easy flashing.

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