cheesestraws
Well-known member
A very quick post: I recently acquired a couple of KeySpan serial adapters from @pcamen: one for use and one to take to bits for science, in case it wouldn't go back together. In fact, the whole thing comes apart and goes back together very cleanly; there's just one screw, under the label:
And the whole thing lifts out as one circuit board. The strain relief slots into the case, it isn't glued in, so it's easy to get out and in.
What have we here?
First of all, we'll have no luck trying to get this to talk LocalTalk; each port is being looked after by an OX16C950, which is a UART. It does not have synchronous serial, and it does not support SDLC.
However, it does claim to have RS485 support, and the line drivers are 75LBC776s, which are full geoport transceivers. Those, plus the inverter between the two, do suggest that differential signalling is probably in place here.
The remaining major chip, unsurprisingly, is an USB interface/microprocessor type affair, part of the communicatively-named "EZ-USB" series. This loads its firmware over USB from the host (!), so in theory this is hackable (though why would you? There are easier ways of getting a custom USB-attached UART).
That's really all there is. When putting the adapter back together, note that the shielding on the USB cable needs to pop into the little copper clip. When I took it to bits this popped out and needed replacing.
So, in summary:
Hope this is useful to someone.
And the whole thing lifts out as one circuit board. The strain relief slots into the case, it isn't glued in, so it's easy to get out and in.
What have we here?
First of all, we'll have no luck trying to get this to talk LocalTalk; each port is being looked after by an OX16C950, which is a UART. It does not have synchronous serial, and it does not support SDLC.
However, it does claim to have RS485 support, and the line drivers are 75LBC776s, which are full geoport transceivers. Those, plus the inverter between the two, do suggest that differential signalling is probably in place here.
The remaining major chip, unsurprisingly, is an USB interface/microprocessor type affair, part of the communicatively-named "EZ-USB" series. This loads its firmware over USB from the host (!), so in theory this is hackable (though why would you? There are easier ways of getting a custom USB-attached UART).
That's really all there is. When putting the adapter back together, note that the shielding on the USB cable needs to pop into the little copper clip. When I took it to bits this popped out and needed replacing.
So, in summary:
- Will do fast asynchronous serial, including in theory with an external clock.
- Will probably do differential signalling.
- Will not do synchronous serial, and definitely not SDLC, so no LocalTalk.
Hope this is useful to someone.