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Re: [Xylo-SDR] Saxo



Hi Edson,

Welcome to the group. I'm a complete novice at FPGA's but slowly making my way up the learning curve.

Bill and I are working on interfacing a Wolfson WM8785 A/D converter to the Xylo board and then via USB2 to the PC. We are both writing in Verilog.

So far both of us have been able to get data from the A/D and I have it playing back via PortAudio on the PC. Currently I'm working on looping back the sent audio from the A/D back over the USB and into a single bit D/A converter on the FPGA. The simulation looks OK but I found out early in the learning curve that does not mean it will work on the hardware! I don't have access to my hardware for about a week since it's being used by a student of mine to do the same project in VHDL (which she has done totally successfully).

Whilst we are using the Wolfson A/D initially, since we both have them, it will be very simple to use any of the other A/D converters that others have proposed with minor code changes.

My initial goals are

1. Build a full duplex USB A/D D/A interface for the PowerSDR code - Bill will tackle the PC end of this :) 2. Add a second A/D for mic input, the TI TLV320AIC23B looks like the chip of choice.
3. Use USB rather than the printer port to control the SDR1000 hardware.

The reason I am not making the Xylo look like a USB Audio Class device is that I don't want the overhead of Windows drives etc (also not being a programmer I would be beyond me!). The disadvantage is that I don't think that we will be able to use VAC without it. In answer to your questions;


1. Is there anyone experimenting with the Xylo/Saxo under Linux?
- not that I am aware of - drop Jean an email he may know.

2. For the current development under Windows, is the USB Audio Class
interface being used? If not what mehcanism is being used to transfer
data from the FX2  to the computer?

- No. I'm using the USB-BulkWrite() etc functions from the Xylo sample code.

3. Is there any attempt to load FPGA code via USB without using the
fpga4fun tools?

- Not that I'm aware of. I know Phil C is looking at using LibUSB ( see http://libusb-win32.sourceforge.net/)

You are welcome to all of my code - just be aware I'm not a programmer and a total beginner at FPGAs!

Phil....VK6APH



----- Original Message ----- From: "Edson Pereira" <ewp_jp@ybb.ne.jp>
To: "Xylo-SDR Discussion" <xylo-sdr@lists.ae5k.us>
Sent: Saturday, January 07, 2006 12:33 PM
Subject: [Xylo-SDR] Saxo



Hello:

I've just received the new Saxo board this morning! I still have a few
things to resolve since I will be using Linux for playing with the board.

My goal is:

a. Have the Saxo enumerate as an USB Audio Class device so that I can
leverage ALSA and Jack under Linux.
b. Use the USB HID interface to communicate with the FX2 8051
microcontroller.
c. Implement a parallel port interface under the FX2 control so that I
can control the SDR-1000.

For data acquisition, I will initially be using the AD1838 CODEC since I
have it in hand. Later I may change the CODEC to separate ADC/DACs with
higher dynamic range.

A few questions to the group:

1. Is there anyone experimenting with the Xylo/Saxo under Linux?
2. For the current development under Windows, is the USB Audio Class
interface being used? If not what mehcanism is being used to transfer
data from the FX2  to the computer?
3. Is there any attempt to load FPGA code via USB without using the
fpga4fun tools?

Since I don't have any experience in programming FPGAs, I will have to
slowly learn it. I want to use the FPGA just as an I2S interface plus
FIFO for interfacing the FX2 with the CODEC chip. Does anyone have any
code fragment I could use for this?

73,

-- Edson, pu1jte, n1vtn, 7n4ncl

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