Community: Message List

Re: Simple Tutorial?

support@line6.com — Sun, 15 Apr 2012 00:35:43 GMT

All of the DSP56364 registers are available. However, I think a couple of the address registers are reserved for interrupt processing in the sample code.

Re: Simple Tutorial?

support@line6.com — Thu, 12 Apr 2012 12:09:52 GMT

You don't have to worry about timing for a simple volume pedal. The processing in the TwoBandStereoEQ sample code happens in one of the sample receive interrupts (called once per sample). The knob and switch registers are defined at the top of the sample file (Knob_1, Switch_1, etc.). For debugging, you can also write to the Debug_Read_from_DSP_x registers to display values in the UI.

Here are a few simple things to get started:

Remove the calls (bsr) to Generate_Coeffs and TwoBand_EQ to create a pass-through (see previous reply).
Set Debug_Read_from_DSP_1 to 0x000001 when the effect is on and 0x000000 when the effect is off. Look for the code that turns LED_Green on/off based on the footswitch. (Note that the Generate_Coeffs subroutine also writes to the debug registers.)
Mute the signal (e.g., by multiplying input by 0) when the effect is off.
Multiply the signal by the Knob_1 value to create a simple volume pedal.

Once you get those basic things working, you can smooth the volume changes to avoid clicks and zipper noises. Then add log scaling to give the knob a better response.

Re: Simple Tutorial?

support@line6.com — Thu, 12 Apr 2012 00:05:19 GMT

I'm not aware of any simple tutorials out there, but you could start with the two band stereo EQ sample code. First build it and download to the pedal. Once you have that working, strip out the processing code so it is just a pass through.

Here is the code that processes both channels:

;Process Left Channel (left input sample is in a)

move #>Switch_1,r6 ; point to x:mem (switch states)

move #>Filter_1_K,r4 ; point to x:mem (coefficients)

move #>Filter_1_A_Left,r3 ; point to y:mem (filter mem)

bsr TwoBand_EQ ; input in a, output in a

move a,y:LeftOutput

;Process Right Channel (r6 is currently pointing to Switch 1)

move y:RightInput,a ; load right input sample in a

move #>Filter_1_K,r4 ; point to x:mem (coefficients)

move #>Filter_1_A_Right,r3 ; point to y:mem (filter mem)

bsr TwoBand_EQ ; input in a, output in a

move a,y:RightOutput

To make it a pass through, change the above block to:

;Process Left Channel (left input sample is in a)

; do your own processing here

move a,y:LeftOutput

;Process Right Channel (r6 is currently pointing to Switch 1)

move y:RightInput,a ; load right input sample in a

; do your own processing here

move a,y:RightOutput

Everything under "Common Subroutines" can be deleted (unless you want to use them). Then start building a simple volume pedal. Use git/subversion/whatever and commit/checkin frequently so you can back up as soon as you take a wrong turn.

Re: Status of this product

support@line6.com — Sun, 15 Jan 2012 01:27:27 GMT

The Line 6 store shows 22 blank modules in stock, but if you try to add them to your cart it won't let you:

"Out of Stock (22 in stock)"

Re: FIR filter: how to use memory?

support@line6.com — Sat, 18 Jun 2011 02:10:37 GMT

One problem I see is that fir_state is starting at $100. For modulo 512 addressing, the base address needs to be a multiple of 2^k. For 512 taps, k=9, so the starting address should be $000 or $200. (For 100 taps, k=7 so 2^k=128 and $100 (256 decimal) is a multiple of that).

You can verify that all of your coefficients are loaded by copying the last coefficient from y memory to one of the read-from-DSP debug registers.

Re: FIR filter: how to use memory?

support@line6.com — Sun, 05 Jun 2011 13:19:45 GMT

IIRC, you will only be able to 512 taps using MACs with X/Y memory and modulo addressing, because you need to store the coefficients in program memory for initialization. I describe that approach below, but you also might want to read the coefficients directly from program memory in your FIR (see the "Pitch detection/octave effect" thread for ideas).

You can allocate arrays in X and Y memory like the following. For modulo-1024 addressing, each array needs to start at a multiple of 1024 within its address space. The simplest way to do that is to put them at the beginning of the section.

org x:$000

fir_state ds 1024

org y:$000

fir_coeffs ds 1024

For initializing tables in X or Y memory from program memory, you can define a global data section after the rest of your code:

section P_DATA_MEMORY global

org p:

; Table values

COEFF_0 dc $000000

COEFF_1 dc $000001

.....

You need to be careful about using too much program memory - your global data section will get truncated without warning. (Note that the DSP56k assembler allows you to initialize the coefficients directly in program memory (dc), but it won't work with the TCDDK.)

Then in your initialization code, copy it to an address in Y memory:

move #COEFF_0,r0 ; address in program memory

move #fir_coeffs,r4 ; address in Y memory

do #1024,init_coeffs_end ; repeat for number of entries

move p:(r0)+,y0

move y0,x:(r4)+

init_coeffs_end:

Also, don't forget to clear the filter state.

Use post-increment addressing to increment the addresses in your FIR loop. The DSP56K has a modulo addressing mode to implement the delay line; each Rn register has an Mn register that you can set to modulus-1. See Section 4.5.3 of the DSP56300 Family Manual for more details. You can find examples of DSP56K FIRs on the web, but the basic idea is something like this (I didn't assemble/test this):

; once during initialization:

move #fir_state,r0 ; state

move #1023,m0 ; mod(1024)

move #fir_coeffs,r4 ; coefficients

move #1023,m4 ; mod(1024)

; for each sample:

move y:LeftInput,x0 ; input sample

; FIR

clr a x0,x:(r0)+ y:(r4)+,y0

rep 1023

mac x0,y0,a x:(r0)+,x0 y:(r4)+,y0

macr x0,y0,a (r0)- ; round and shift input samples

move a,y:RightOutput ; output sample

Re: Pitch detection/octave effect

support@line6.com — Tue, 03 May 2011 23:45:05 GMT

For initializing tables in X or Y memory from program memory, you can define a global data section after the rest of your code:

section P_DATA_MEMORY global

org p:

; Table values

CONST_FOO_0 dc $000000

CONST_FOO_1 dc $000001

.....

The in your initialization code, copy it to an address in X memory:

; initialize table

move #CONST_FOO_0,r0 ; address in program memory

move #foo_table,r3 ; address in X memory

do #100,init_table_done ; repeat for number of entries

move p:(r0)+,x1

move x1,x:(r3)+

init_table_done:

Hope that helps.

Re: Sample ToneCore effect code, volume preset already written?

support@line6.com — Sun, 06 Feb 2011 14:55:51 GMT

Assembly language is the only practical option to develop code for the ToneCore DSP Development Kit. There is some sample code in the Unofficial ToneCore DDK wiki.

You could build a volume preset pedal by using the tap switch to cycle through six levels set by the pots, with a crossfade or bandlimited step to make it glitch free. However, that is a steep learning curve for an effect that would use very little of the ToneCore's available DSP, and your signal will always be going through the ADC and DAC.

You might want to consider building an analog pedal instead (or having someone build a custom one). R.G. Keen has an article with schematics for a six volume preset pedal.

Another alternative would be to find a cheap digital multi-effects pedal that can switch presets without glitching. If you just wanted to switch volume, you could set up some simple presets with different gains.

Re: development software

support@line6.com — Thu, 13 Jan 2011 00:32:49 GMT

GNU Octave is free and similar to MATLAB. SciPy (based on Python) is another good, free choice.

Re: TwoBandSterioEQ.cld Error Message

support@line6.com — Tue, 05 Oct 2010 00:28:19 GMT

Try running the GUI as Administrator. It is mentioned in the troubleshooting section of the TCDDK Users Guide, specifically for Vista, but I assume the same would be true for Windows 7.