Building a 4-Track Audio Looper with Blackfin BF533 EZ-KIT
This project utilizes the Blackfin BF533 EZ-KIT to create a versatile 4-track audio looper. It incorporates 32MB of external SDRAM for audio storage and features push buttons to toggle recording on and off. LEDs provide visual feedback on the recording status. The system is ideal for musicians looking to layer tracks for a fuller sound or DJs seeking to seamlessly mix songs. The audio data is recorded in four partitions of SDRAM, ensuring efficient storage and playback of each channel.
Building a 4-Track Audio Looper with Blackfin BF533 EZ-KIT
E N D
Presentation Transcript
ECE 3551 Final Project by Brian Robl Loop Board
Objectives • Use the Blackfin BF533 EZ-KIT to create a 4 track audio looper. • Utilize 32MB of external SDRAM. • Push buttons used to toggle recording off and on. • LEDs signify if recording is enabled or disabled. • Pointers used to record and loop audio.
Common Uses • Musicians use loop pedals to overlay recorded tracks over one another. • Make a fuller sound • Creating songs • Djs may use this to mix songs together.
Recording to the SDRAM • SDRAM split into 4 partitions. One for each track. ///////////Right Channel0 Partition//////////////////////// #define pRAMstartR (volatileunsignedint *)0x800000 #define pRAMendR (volatileunsignedint *)0xFFFFFC ///////////Right Channel1 Partition//////////////////////// #define pRAMstartR1 (volatileunsignedint *)0x1800000 #define pRAMendR1 (volatileunsignedint *)0x1FFFFFC ///////////Left Channel0 Partition//////////////////////// #define pRAMstartL (volatileunsignedint *)0x00000000 #define pRAMendL (volatileunsignedint *)0x7FFFFC ///////////Left Channel1 Partition//////////////////////// #define pRAMstartL1 (volatileunsignedint *)0x1000000 #define pRAMendL1 (volatileunsignedint *)0x17FFFFC
Recording Cont. • Pointer set to starting address of partition. • Stores sample and then address gets incremented. if(channel == 0) { if(pRecordR <= pRAMendR) //if record pointer address is less than ending address for Channel0R partition { iChannel0RightOut = iChannel0RightIn; //output input in real-time *pRecordR = iChannel0RightIn; //input becomes recorded pRecordR++; //increment address for record pointer if(pRecordR > pRAMendR) { pRecordR = pRAMstartR; pF8_LED = 0x00; //turn off LED ucActive = pF8_LED|pF9_LED|pF10_LED|pF11_LED; *pFlashA_PortB_Data = ucActive; } Process_Data(); //output rest
Loop Playback • Another pointer is used to iterate through the memory partition that contains data and store it in the output. if(channel == 0) { if(playR < pRecordR) //if play pointer address is less than end recording pointer address { iChannel0RightOut = *playR; //output recorded data until end of recording playR++; //increment address for play pointer } elseif(playR >= pRecordR) //if end of recording address is reached, { playR = pStopR; //reset pointer to beginning } Process_Data(); //output recording
Playback cont. • Recorded audio played back from each output channel. • Ichannel0LeftOut • Ichannel0RightOut • Ichannel1LeftOut • Ichannel1RightOut
Questions? • Thank you for your attention.
