VoiceChanger_TIDSP

This project uses TI DSP board(BOOST5545ULP) to realize the real-time voice changing system based on the principle of fractional frequency conversion

Preconditon

• Please make sure you've went through C5545 DSP BoosterPack Software User’s Guide,and you can build or debug demos C5545 DSP BoosterPack Software Installer 01.01.00.00.
  
• Download this project and import it to ccs.Then create two new subfolders(audio_common and common) and link them to counterparts in one of the demos.
• Moreover,To avoid gpio_ISR redefinition conflicts, you need to delete, or comment out the gpio_ISR function in audio_common.h and audio_common.c, or change the gpio_ISR function to static like i do.

How to Run?

• Just like running other projects in ccs.
  • Build
  • Launch Target Configuration(Create a new C5545 Target configuration file if you don't have one)
  • Connect Target(Make sure that the board and PC are normally connected through the debug port and powered on)
  • Load Programs
  • Resume.
    Or you could just simply hit the Debug button,The pitch of the sound input from the onboard mic will be lowered and output from the headphone port, you should be able to hear it when you plug in headphones or speakers.
• The program has a set of simple control logic. Press sw2 button to pause or resume playback, press sw3 to turn off or turn on the voice changing effect, press sw4 to change the upsampling or downsampling working mode.The three are independent of each other.
• Voice changing effect adjustment: In dma.h,there are two Macros(A and B),the output sound pitch will rise or fall by B/A.So you can manipulate these two parameters to achieve different voice changing effects.By default,B/A = 3/2.

System Architecture

The above diagram illustrates the system architecture.Some parameters need to be specified as follows

• Sampling Rate:48KHz
• Bit depth:16 bits
• PingPong buffer Size: 512 words
• System Clock:100MHz
  Moreover,In order to eliminate the frequency components brought by downsampling, we designed an 11th-order low-pass FIR filter with a cutoff frequency of pi/8 in matlab.The filter will only work when downsampling.FIR filter related functions and parameters are in the fir.c and fir.h, you can also adjust the filter yourself.

Explanation

This project is an assignment in the DSP practical course.So the time is a bit rushed, the code is modified based on the routine, some places are not standardized, please forgive me.
If you have any questions, you can ask them in Issues, and pull requests for improvements are also welcome.