The Open source SDSL Debug and Connectivity Unit (OSDCU) project was originally conceived in the summer of SE 45 (2006). The name reflects a dual function:
The relative priorities of these intended functions have changed over the years. At first when many of the SDSL flavors were shrouded in mystery, a debug instrument (SDSL analyser) was our primary need, but then we got that task accomplished using our Hack-o-Rocket platform without waiting for the OSDCU. We had then resumed the OSDCU project focusing on the connectivity part. But now that a bunch of XSB-2000 units have suddenly landed in our lap, the urgency of bringing the equivalent functionality up on our OSDCU has subsided somewhat. We can now take our time with that, and in the meantime the OSDCU has become useful as a debug instrument once again: the SCC2 connection to the DCE port has proven useful as an HDLC dumper for analysing EIA-422 bit streams from other devices.
VersaDSU is another name we are using for the same thing; it is a more user-oriented name that reflects the device's functionality as a versatile DSU for a multitude of very different SDSL flavors as explained below.
OSDCU is a hardware design of our very own. It is a 130x165 mm printed circuit board (PCB) designed for mounting in a simple metal enclosure similar to the CopperRocket. It takes DC power (+5 V, +12 V and -12 V) from an Amperor AOF25 open frame power supply which in turn takes AC mains power (either American or European, auto-switching).
The OSDCU board contains an MC68302 microprocessor subsystem, an RS8973 SDSL bitpump and an EIA-530 synchronous serial DCE port. (See the hardware design specification for more details.) The external connectors are the SDSL jack, the EIA-530 port (DB25F) and an asynchronous serial console port which runs at 9600 baud and enables configuration, monitoring, control and hacking functions. The software for the MC68302 remains to be finished, but the following modes of operation are planned:
A totally bit-transparent DSU for SDSL Flavor B: the RS8973 bitpump's RDAT and TDAT pins are MUXed directly to the EIA-530 DCE port. This mode is a recreation of the XSB-2000 DSU.
A Layer 2 protocol converter for SDSL/ATM, talking either Flavor A or the Nokia flavor on the SDSL side and presenting HDLC on the EIA-530 side. There are a number of industry standard ways for doing this conversion; our only real concern here is whether our CPU can perform this conversion fast enough to keep up with high data rates (Covad SDSL for example can go up to 1536 kbps). We'll have to just try it and see how well it works.
A debug, hacking and experimentation platform similar to the Hack-o-Rocket.
We have fabricated the first batch of 5 PCBs and populated one of them. We now have a working board (shown in the photo at the top of this page) which we are using for software development and functionality bring-up. As far as the DSU functionality goes, we now have the bit-transparent function working (at a pre-alpha level), but we have yet to begin working on the Layer 2 converter function.
For more information please see the status section on the Open WAN Connectivity Project main page.
The OSDCU is not a usable DSU product yet, and the short and blunt answer is that it will probably become one if and only if someone comes forward and expresses an interest in seeing that happen.
In the meantime please use the remaining stash of XSB-2000 DSUs.
We have built one OSDCU board for our own development use, but we have enough parts (PCBs and components) to make up to 4 more. If you are a hacker with a burning desire to get an OSDCU board for your own open source SDSL development or for pure hacking pleasure, we can make one for you for about $150 USD, as long as the following is clear:
The $150 figure is based on the cost of the extra parts we would need to get in addition to the ones we already have (around $40), the amount we would have to pay to have another board assembled (around $60), and miscellaneous overhead expenses like shipping, vendor surcharges and gas that would be burned driving around to handle the logistics of it all (the remaining $50). There is no profit margin for us in that price!
If you think you can build an OSDCU yourself for less than that, you are more than welcome to try: the gerber files, the BOM and everything else you would need is available on our FTP site.
The complete source for the OSDCU (hardware and software) can be checked out of our CVS repository as follows:
cvs -d :pserver:anoncvs@ifctfvax.Harhan.ORG:/fs1/IFCTF-cvs co OSDCU
We also have the following for the convenience of anyone interested: