Parts: Parallax VGA/Dual PS/2 breadboard adapter

by on Aug.31, 2009, under Embedded devices, Hardware, Product Reviews

parallax_logoSeeded by a submission made by me, Parallax announced very recently that they have released a new product, a VGA /Dual PS/2 breadboard adapter.   Today, I got my hands on the new adapter and I couldn’t be happier.  Read on for more details and my first impression regarding this new product which I’m sure will generate a lot of new application ideas for their Propeller microcontroller platform.

I have to admit that when I had started looking into more advanced microprocessors, I really hadn’t given the Propeller a good looking over.  When I heard about the PropIRC project I had to admit that my interest was piqued.  I had read about the Propeller being used to drive a television set via a composite connector but here was a fully implemented VGA compatible application that was not only impressively executed by Harrison Pham in the build of his PropIRC, but also demonstrated the Propeller’s full range of capabilities.

I ordered my Propeller Education Kit (40 pin DIP version) and was excited to start coding.  By using the Propeller Object Exchange I was able to quickly test just how easy it was to add a PS/2 mouse and keyboard to my testbed.  When I ordered the TV breadboard adapter, I was even more enthralled with the idea of being able to create a standalone device or an embedded device that could interface to standard computer hardware (monitor, keyboard and mouse).  Although I was inspired, I was let down by the complexity of the VGA connection, requiring at least 8 maybe 10 pins to interface, in addition to that, no breaboard connection existed for the VGA connection.

I wrote to Parallax a few months ago and asked them to consider building a VGA/Dual PS2 port breadboard add-on that was a lot like their Propeller Prototype board which already had the solder pads on it for the related Propeller Proto Board accessory kit.  Within an hour, I had an email back from a representative at Parallax that they talked to the lead engineer and they loved the idea.  A few minutes after that, I had an email from Jim Carey saying that not only did they like the idea, they were going to ship me a couple free.  Add to that my surprise when he also stated that he would also give me a Propeller Servo Controller for free as a bonus thank you.

Talk about a company that really listens to their customers.  Not only did they like the idea, but they were going to give me two just for emailing them a product suggestion and on top of that, give me one of their newest products!  I think it’s safe to say that I’m a Parallax customer for life.  I just need to buckle down and start learning the Propeller code and get good with programming it.

But, enough of my story, let’s review the hardware!

In the VGA/PS2 adapter kit, (Parallax part # 28075) you get the Dual PS/2 and VGA adapter, a single row pin header and a small PCB with the resistors in place already.

parts picture

parts picture

The kit comes with the resistors pre-mounted to the PCB, so all you have to do is to solder the SIP  connector and the VGA module.  The completed module looks like this:

Front view, assembled module

Front view, assembled module

Here is a side view of the module after it’s been assembled:

side profile picture

side profile picture

The really cool thing about this is that by NOT assembling the module completely, this leaves an opportunity to mount the module in a case and use ribbon cables to attach to your project’s main PCB while still providing you the flexibility of being able to use a more modular build.  Since these connectors may wear out over time, it’s a lot easier to replace the module and a ribbon cable that is easily de-soldered, than it would be to desolder the entire module from your project’s main PCB.

Here is a quick shot of what it looks like all jumpered in.  The SIP header allows the module to plug in straight into the breadboard and a series of jumper wires connects the module to the Propeller IO pins:

Propeller VGA/PS2 module all wired up

Propeller VGA/PS2 module all wired up

With that said, of course I set out to test it fully.  I looked to the Parallax Object Exchange and found an object that used the original Hi-Res VGA Driver written by Chip Gracey.  This object provided a Text based GUI implementation and was written by Allen Marincak.  You can download the GUI implementation from Parallax’s Object Exchange here and the original Hi-Res VGA driver here.

If you are going to try this out for yourself, the pins are straight across, from bottom to top (or right to left using the above picture) with “V” (vertical sync) being connected to IO pin 16, and Keyboard Clock being connected to IO pin 27.

Here is a screenshot of the VGA GUI implementation fully operational:

VGA GUI implementation

VGA GUI implementation

This implementation supports full keyboard and mouse connectivity with little to no overhead on processing.  The mouse “pointer” is the single green box to the left of the upper left most text box.

On a personal level, I am very excited about this and look forward to using the VGA library and the VGA GUI library in my own implementations.

Manufacturer: Parallax

Product Link: VGA-Ps2 Breadboard adapter

Part Cost: $12.99 USD (as of this posting) + shipping.

Verdict: Highly recommended for anyone seeking to use VGA and PS2 mouse/keyboard in their application design but can’t afford the full Professional Development Board.

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