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ECB ATB Active Termination Board

I've completed the new ATB version and done some simple tests with my scope on the ECB bus.

I set the voltage to 2.7Volt.

All tests:

4×4 ECB bus board with:

SBC with 74ls244/245 bus drivers.

PropIO board with 74ls244/245 bus drivers (same brand as SBC).

Prototype III board to tap into bus pins easier.

And ATB new version.

Power supply on the 4×4 = 4.96-5.01Volt

Text	Image
ATB completed: Note that the RN5 only needs 6 pins, but pin1 is connected to square pad under the board.
This is A0 with no ATB
And this is A0 with ATB: ATB draw about 100mA. The signal on A0 looks cleaner on top with ATB, but there is some ringing added there. Rise times are about the same as far as I could see.
This is D0 without ATB:
…and here is D0 with ATB. This kind of noise does not look good??
Experiment to clean up D0-D7 signals	I changed the RR1 from 270ohm to 10K and that helped (No noise) but 10K is basically the same as turn Active Termination off for D0-D7? When the RR1 was changed to 10k I got the same curves/pattern on my scope as no ATB. I didn't try 4K7 or 2K2. Maybe my bus is noisy on D0-7? I tried different 74xxx245 (HCT, ACT and AHCT) but could get the ATB to clean up D0-7 lines with ATB. I even tried different OpAmps and also tuned the voltage on the ATB from 2.2 to 3volts.