Fabric8

Are you interested in testing out the Fabric8, Arachnid Labs' next product?

We're now looking for a very limited number of alpha testers to try the fabric8 breakouts. Testers will be sent a selection of fabric8 breakout boards, and an adapter for the official Greenpak development kit that permits their use. In order to participate, you will need to buy an official Greenpak3 development kit from Dialog Semiconductor.

Interested? Email me at nick@arachnidlabs with a short description of what you'd like to do with the Fabric8 to apply.

The first programmer prototype is designed! You can see the layout here.

It's a fairly straightforward design, with an Arm Cortex microcontroller with USB doing the heavy lifting. The whole programmer board can be plugged into a breadboard for easy testing of new designs.

A capacitative voltage doubler and zener shunt regulator generates the 7.5V needed to program the greenpak, while a couple of analog switches prevent the programming signals from reaching the breadboarded device.

Here's the schematic in all its glory:

I'm holding off producing any samples until we've got a reasonable design and attachment method for the programming clip/socket discussed in the previous post.

I've ordered and received the first prototype breakout boards for the Fabric8, and they work perfectly! I've also got an adapter PCB that allows for programming a Fabric8 from the official dev kit, which is perfect until we're done developing the Fabric8 dev kit.

You can see the design of the breakout boards here and the design of the adapter here. They're standard DIP 0.3" pitch and 0.1" spacing. VCC and GND pins match the standard used for 7400-series logic, with VCC in the top right and GND in the lower left. The bottom rows can be broken off to make ICs with fewer than 20 pins. Other than that I've tried to keep the native Greenpak pin numbering as much as possible I'll be shipping out breakouts and adapters to a few select Alpha testers soon.

Aside from being an opportunity to solicit feedback on the breakouts and development process, the adapter board serves as an opportunity to work on the design of the retaining clip for attaching the breakouts to the programmers. The goal is to be able to insert the breakout boards into the programmer without headers soldered on, using a row of spring pins to make contact with the pads. Once the device is programmed, it can be removed from the programmer and have headers - or wires - soldered in.

This requires a custom clip or socket of some sort. I'm not yet certain how it will look - some experimentation will be required. It's likely that it will be 3d printed or (eventually) injection moulded; I'm hoping for a single piece design for simplicity.