Using a PC like a "pendrive"

Don't know. One of your main problims might be listening to s**te music. However, if you have some sellotape then you can attach a pen to your PC and then you should be in business.

DNA

Is there any chance that the Hi-Fi supports 'dual mode' USB (I think its called USB-OTG)? If so, it can operate a either a host (working with a pen drive), or a client when connected to another host. If at least one device can't dynamically switch to being the USB client, you'll need a USB bridge (to keep power supply and signals connected properly). The USB standard doesn't recognize 'null modem' cables.

I've looked for the dual mode capability in PCs myself and come up empty (so far) for more or less the same idea as what you have. Even with a USB bridge, I haven't found PC software to emulate a USB drive.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Power corrupts.  And atomic power corrupts atomically.

If you have the Grundig Ovation 2 HiFi type unit then be aware that the USB port on this unit is a host type port designed to permit connection of external hard drives, and memory stick type devices as a peripheral device to become a mounted file system. From this file system the Grundig can pull off files to play on the stereo.

Your PC USB port is actually also confugured as a "host" type port and can also mount file systems from the same type of periphera type USB devices. There is not a normal direct way to connect USB host to host devices together. The software behind host devices expects to normally talk specifically to peripheral type devices. (This is one of the reasons for why USB devices that follow the USB standards connect with cables that are different on each end). To connect up the stereo to the PC in a manner like you describe at a minimum requires some type of USB bridging device. These are made in one form as the USB peer-to-peer networking devices that you can find for sale. These require special software on both ends to permit the bridge connection to work as a network link. Different special software could be made to support the PC end disk drive emulation like you refer too but is doubtful that this is directly available in a format that the Grundig would be able to access without some software special drivers in the Grundig to be installed.

- mkaras

You could look at this device:

...and others like it. You may be able to eek your functionality through a bridge of this type.

- mkaras

Thanks guys. There is no software only solution to this, am I right?

Actually, it's all software problem. We have all the hardware available, but no time to do the software yet. If you are good in software, we can provide you with a USB-OTG board with serial or parallel interface to the PC.

Ok, ready to go!!! Send it to me then...

linnix escreveu:

We only have one working sample chip left. If you request a sample for AT90USB1287-16MU from Atmel, I will put it in a board and mail it to for you. If you show working codes, we will send you as many as you need.

Ok, just send me an email explaining how to request and where to send it. I'll begin writing software as soon as possible!

Denis linnix escreveu:

My email is invalid and I am not sure how to get yours either. Here is a picture of the unit:

and you can send me a message at the bottom of the page.

Go to the Atmel site and request for a sample of AT90USB1287-16MU. We will be buying the non-usb chips, but we did get some usb samples from Atmel to check out the board. We could Jtag the chip, but did not go much further. The board has a 8 channel analog multipler and RS232 driver. There are 20 I/O pins plus power and ground in a dual row pin header. TWI (SDA, SCK) signals are brought out of the bottom headers.

Two major features we need to implement are (1) read/write some external storages (PC, SD or EEPROM) via TWI. and later ( 2) USB-OTG

What you need is a USB slave device which speaks the "mass storage" protocol.

For instance, have a look at the NET2280 device:

This device is a generic USB slave, which needs a driver to make it talk a specific protocol, like mass storage.

The Linux kernel has support for this. Look up "USB gadget drivers". I assume there are Windows drivers around too.

This stuff is not in mainstream use - it's mainly done by people who develop USB hardware. Expect an interesting price tag.

To solve your problem I would recommend using a pendrive. You could even build a switch to electrically change the pendrive from your PC to the stereo and back. It's only 4 wires.

Kind regards,

Iwo

Or USB OTG with transparent mapping to a mass storage device.

You can use

for the USB side and TWI, parallel or serial on the PC side. Alternatively, you can use two as slave devices and TWI between them for best performance.

We plan to make ours for $10 to $15, with the AT90USB128 costing around $5.

Only 2, you don't need to switch power and ground.

As I said before, it's just software and lots of it.

Could you explain why OTG is relevant in this context? The OP wanted a slave device and I doubt the Hi-Fi speaks host negotiation.

I notice a lot of data massaging in the AT90USB128 data sheet. The so-called USB2.0 slave block is in reality USB1.1 (12 MBit only, USB2.0 *compatible*), and there is no USB master hardware, so all the HNP block can do is talk to a OTG device and switch *it* into master mode.

Please correct me if I'm wrong.

I also don't understand what you mean by transparent mapping. The request was to somehow attach the PC's hard drive as a USB slave to a Hi-Fi which speaks the USB mass storage protocol.

Your device could implement the mass storage protocol inside the AVR (is that the "lots of software" you mentioned?) and then talk some other protocol to the PC to get access to the PC's harddrive.

Is that the idea?

Kind regards,

Iwo

OTG negotiates as host or slave as needed. It can also be set to either host or slave.

I have to double check on the data sheet, but all we need is USB slave here anyway.

With the device acting as slave, it can re-package the requests over other physical links (serial, parallel or IDE) to the PC. Of course, you would need a driver on the PC to handle the mapping to physical storages.

Perhaps the easiest way is to multiplex the IDE channel directly, without hacking into the PC software.

This is possible as well.