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Arduino-based front panel for QBUS backplanes

Mal

Experienced Member
Joined
Apr 3, 2008
Messages
91
Just thought I'd post a link here to a new Arduino-based project.

The Arduino monitors some front panel switches (Power On/Off, Run/Halt, LTC On/Off, Restart) and provides the necessary output signals for the 10-pin connector on the rear of a QBUS backplane (BDCOK H, BPOK H, BEVNT L, BHALT L).

As part of the power-up/power-down sequence for the PDP-11, it also turns an ATX power supply on and off, to power the backplane.

The LTC output defaults to 60Hz, but can also be configured for 50 Hz by adding a jumper.

The hardware is very simple: just an Arduino UNO. No Arduino "shield" or I/O electronics are required. You will of course need to wire up the front panel controls (4 switches and 2 LEDs) and fabricate the cabling to the ATX power supply and to the QBUS backplane.

Here's the link -> http://avitech.com.au/?page_id=1657

Feedback and bug reports are most welcome.

Malcolm.

20170714_084652 (Medium).jpg 20170714_101334 (Medium).jpg
 

Mal

Experienced Member
Joined
Apr 3, 2008
Messages
91
Thanks Al - I've added a link to your project on my project page.
 

glitch

Veteran Member
Joined
Feb 1, 2010
Messages
5,011
Location
Central VA
Do note that cooling is not *optional* for QBus backplanes -- you can and most likely will cook your CPU board without a fan! A desk fan aimed at the side of the card cage, allowing air to pass over and under all of the inserted cards, would be sufficient.


Ouch! $30 USD for something John Wilson whipped up to start with!
 

jackrubin

Veteran Member
Joined
Mar 12, 2004
Messages
846
Location
Chicago, IL and Buchanan, MI
@glitch - The main cost of Brad's setup seems to be the raw board priced at $20 - something like this is probably a $5 item from OSHPark. The rest of his BOM is only $7 and he's offered up the source and schematic, so not really a bad deal.

Jack
 

Dare

Experienced Member
Joined
Dec 28, 2015
Messages
71
I thought I'd resurrect this thread to show off my own interpretation of Malcom's excellent Arduino-based QBUS front panel. Mine is based on a knock-off Arduino Nano that cost around $4, plus a smattering of other parts. It's minimal, but quite functional for my purposes.

attachment.php


attachment.php


Note that the switch labels have yet to be added in these photos. The switches are (L to R): Power, Run/Halt, LTC Enable/Disable and Restart.

Mine runs a slightly modified version of Malcom's software that adapts it to the Nano. I've contributed this code back to him for future inclusion on his project page.

A big thank you to Malcom for developing this and making it available to the community. Anyone looking to build a skeletal QBUS system should definitely consider throwing one of these together.

--Jay
 

8008guy

Veteran Member
Joined
Jun 25, 2014
Messages
584
Location
Salt Lake City, Utah
+1

Nice job on the write up.

Last year I did one using ttl and discreet components on a bread board, lol... It's still on a bread board.
 
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