Keith, thanks for the info. I've done some simple logic analyzers and
A/Ds connected to the parallel port with rates around 500Ksps. I've been
wanting to do a more versatile, stand-alone, unit for a long time. I wanted
RS232 (or 485) so that I can get some distance between the DSO and PC. There
are a lot of ways to connect the two and I have'nt decided yet. I have some
IrDA eval boards and one possibility is IrDA with fiber or differential
drivers instead of IR. Note, this is an in-house project for my own use.
I was also looking at flash A/D's and using my Tek 465B as a front-end.

   - Tom

At 02:13 PM 12/12/97 +0000, you wrote:
>Tom Handley wrote:
>> I've had a DSO project on the `back burner' for a long time.
>> I recently had a requirement to analyze IR remote signals so I'm going to
> finish the project.
>
>IR carriers are only around 33-38kHz. IrDA is only 115 kBaud - 4 MBaud.
>If you have some kind of ADC driven by your printer port, you could still
have a
> very useful gadget with a HUGE
>memory. Which you can program in C instead of PIC assembly.
>
>> Both connect to a bidirectional PC parallel port.
>> My design will be PIC-based and connect to the serial port.
>
>I'd stick with parallel if I were you. You will appreciate it when you want to
> upload data into your PC.
>And make sure you design for a commonly available cable such as the Laplink
> transfer cable.
>This is only 4 data bits + 1 or 2 handshake bits in either direction.
>It suits all printer ports, whereas an 8-bit interface might exclude itself
from
> simpler PCs.
>Either that or try using an LPT<->I2C interface.
>This won't be slowed by baudrates, won't need a MAX232 chip, or the hassle of
> baud rate generation.
>The PIC UARTs don't look very accurate at high speeds, while I2C doesn't need
> precise clocks.
>
>I hear the very fastest scopes use a bit of co-ax cable as a delay line, and
> digitise signals from points along
>it. but that's stretching a budget.
>
>