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

TextImage

ATB completed:

Note that the RN5 only needs 6 pins, but pin1 is connected to square pad under the board.
www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_speed3ple_images_img_20210325_201911small.jpg
This is A0 with no ATBwww.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_speed3ple_images_img_20210325_201429small.jpg


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.

www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_speed3ple_images_img_20210325_201444small.jpg
This is D0 without ATB:www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_speed3ple_images_img_20210326_182647small.jpg

…and here is D0 with ATB.

This kind of noise does not look good??
www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_speed3ple_images_img_20210326_183930small.jpg
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.


builderpages/speed3ple/ecb-atb.txt · Last modified: 2021/03/28 15:02 by speed3ple
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