04-08-2013 01:34 AM
Hey everyone,I'm just learning how to use the Audio CODEC on NIOS II with the DE2 board. I wrote the following assembly code to generate a square wave and use it to produce an output tone: .equ ADDR_AUDIODACFIFO, 0x10003040 .global main main: movia r2, ADDR_AUDIODACFIFO # Set up the square wave's positive pulse preloop1: movi r3, 10000 movi r4, 22 # Send 22 outputs to the FIFO loop1: stwio r3, 8(r2) stwio r3, 12(r2) subi r4, r4, 1 beq r4, r0, preloop2 br loop1 # Set up the square wave's negative pulse preloop2: movi r3, -10000 movi r4, 22 # Send 22 outputs to the FIFO loop2: stwio r3, 8(r2) stwio r3, 12(r2) subi r4, r4, 1 beq r4, r0, preloop1 br loop2 It doesn't seem to be working - nothing is being written to the audio codec's FIFOs. Does anyone know what I need to do to produce a tone? Thanks.