I have seen the Phillips USB chips and they are great for some things. If i wanted to make a USB-Mouse/Keyboard device I'd be buying one right now. Unfortunately my application is slightly more demanding. I would like to create a USB-based digital (and analog but that's incidental to the USB side of things) audio interface for my PC. I won't go intop all the details but the basic features are: - At least 1 if not 2 channels of DAT quality I/O (24 bit, 48kHz, stereo x 4 = 1152 Kbyte/s. 2 isochronous capable endpoint pairs) - 2 MIDI I/O (4x ~30000bps max. = 15Kbytes/s. 1 endpoint pair.) - 1 channel of MPEG/AC-3 compressed audio (<200bit/s = <25Kbytes/s, 1 isochronous endpoint (output only).) - Full control over both audio and MIDI interfaces (at least 1 control endpoint (BTW: anyone know if I can do the control for both MIDI and Dig. Audio on 1 endpoint?)) Total: 1300Kbytes/s (not including protocol overhead) = ~10.5Mbit/s 2 isochronous endpoint pairs 1 standard endpoint pair 1 isochronous endpoint 1-2 control enpoints I could combine the compressed audio endpoint with one of the digital audio I/Os and thus only need 3 Data endpoint pairs and 1-2 control endpoint pairs. Thus, the phillips chips have the following shortcomings: - Speed. While the serial interfaced version supports the full 12Mb/s speed on the USB end it has only 1Mbit/s I2C which ain't enough. The parallel interfaced chip manages 2Mbyte/s to the PIC which would just scrape through the specs say it achieves a max. throughput of 1Mbytes/s in bulk mode (only 1Mbit/s in isochronous which I believe is generally used for audio) Also, it wouldn't be easy to drive the parallel bus (You'd need a PIC with PSP (ifi it'd work) and then you lose 8 pins) and the 2 ADCs, 3 DACs, MPEG/AC-3 decoder and 2 channels of USB-MIDI off the pins and cycles of a PIC would (maybe with a scenix?)). - Configuration. When looking through the Phillips specs I was unable to find any info on configuring the USB interface. i.e. entering Device and class IDs etc. Does this have to be manually handled by the MCU or am I missing something? - Buffers. The specs also seem to lack info on the buffers. They state their is a buffer using internal memory but don't give you any info. The MIDI stream would be fine with any buffer but fair sized buffers are needed for the digital audio. Before someone else points it out, I am aware of the custom digital audio/USB chips made by Phillips. The only problem with these is that you cannot integrate MPEG/AC-3 or MIDI. However they may still be useful (see below). One product I am looking at carefully is the Intel USB MCUs. These are basically a MCS251 with an inbuilt USB interface. They provide a few advantages over the Phillips that I can see: - Speed. They support the full 12Mbit/s standard apparently. - Buffering. They have 1 Mbyte of RAM available for buffering. Thus it can be configured to give 256, 512 or 1024 bytes of buffer for 2 of the ports which should be plenty (the other 2 have 16byte which should be fine for MIDI/control. - Integrated Hub. The 8x930Hx series is a four (or five) port hub where 3 (or four) of the ports are external and 1 is internal. I am considering using this chip as it could significantly reduce many of the problems. For instance one solution would be to implement the MIDI/compressed audio interfaces using the internal port and then attach a Phillips UDA1335 - USB Audio Playback Recording Peripheral (Digital and Analog outputs) to do the uncompressed audio. The only problem with this is I'd need two chips to do the 2 inputs & outputs and I'd have to write my own software to have them device act as only one USB device (in fact I'd have 3, 2 x PCM Digital Audio, 1x Compressed audio /MIDI). As you can see, the phillips device is great but not for my purposes. The only problem I have with the Intel MCU is it's not a PIC (which isn't a problem, it just means I have to learn a new MCU. BTW what are peoples opinions of the Intel MCS 51/251 (it's a bit of a cross between the 2 I gather)). Hence, If Microchip planned to releas a USB capable PIC anytime soon (and I saw rumours that they were) I would investigate this before commiting to the Intel product. Has anyone attempted Digital Audio (PCM or compressed (even better)) or MIDI over USB? Sorry to provide so much info. Tom. ----- Original Message ----- From: German > I don't have any info on this. But have a workaround to use USB with > any mcu. > > > I read somewhere that Microchip might be relewasing a range of chips with > > inbuilt USB interfaces (20xxx I think it was).