Saturday, July 30, 2022

Projects Overview

I have worked on many projects, both professional and personal.  In this section of the site, I plan on detailing some of those projects, what drove them and how I achieved the project goals,  I am not going to go into too much technical detail, but just enough to give you an idea of how things worked and what I came up with for the designs.  Given that some of these designs were completed over 30 years ago, I might be light on detail!

Tuesday, September 3, 2013

Cisco 1841 Memory Upgrade

Note: this was written in 2012 and the technical details reflect that time.

As a contractor, you need to keep your skills up, so I kept a lab at home.  The clients I dealt with were mostly small and medium sized businesses. SMBs don't generally have large networks and I would often use the lab to try out ideas. 

I also liked to browse eBay for cheap gear. If you have looked at the Cisco 1841 router, you would see that many are advertised as having IOS 15, but beware; they often don't have enough memory to run. IOS12 will run on 128MB but IOS15 requires the full 384MB in order to run correctly.

This is what happens when you don't have enough memory:

This has happened to me twice now; twice I have purchased 1841's with IOS 15, and twice they have not had the required amount of memory to run IOS 15.

My first 1841 came with IOS12 and 15 so I just dropped back to 12. This is currently my home router. My latest purchase needs to run IOS15 for my lab work, so I decided to try a memory upgrade.

Memory prior to upgrade

This is the Cisco page showing how to add the additional memory. It is very straight forward requiring only the removal of one screw to get the box open.

Of course you can't just throw any old memory in there. The 1841 comes with either 128MB or 256MB of DRAM, with a single slot for upgrading to 384MB. In my case I have 128MB so I needed a 256MB ram module, and after a little research, This is the one to get.

Installation took maybe all of 5 minutes, and the router is up and running again:

Memory post upgrade

And that is all there is to it. I've been working with the router most of the day, and so far run into no issues with functionality or with the extra memory.

Monday, August 28, 2000

Programmable System on a Chip

In my time working for Ambar components, I had spent a lot of time working and training with the folks at Cypress Semiconductor, so when an FAE position opened up in Texas, they offered me the chance to apply which I did.  I was lucky enough to secure that position, and found myself relocating to the Dallas area. 

One of my first successes with Cypress semiconductor was the work I did with a digital sign maker in Texas.  The types of signs they designed and built are the roadside dot matrix signs. 

The PSoC module

Cypress had a product called PSoC ( Programmable System on a Chip). The PSoC was a small micro controller with configurable I/O which in this case was used for ultra bright LED driving and a serial interface for module to controller communication.  The module drove a small matrix of LEDs.  These modules would be connected together to form one large display panel.

The sign comprising PSoC modules

This is the back view of a completed display module.  The PSoC modules are connected via serial interfaces to a PC card, that handles the graphics and communications requirements of the sign.  The signs could be permanently mounted or portable mounted on a trailer (as seen below)
The completed Item

The completed item shown is one of the first trailer mounted signs.  

Wednesday, August 10, 1994

De Dietrich LED Control Panel

Another display module design that I put together was for the French company De Dietrich, who  manufacture high end cooking equipment, and this module was intended for an oven.  The module required an LED display with custom icons, two switches and a rotary switch encoder.

The completed module

This module comprised two designs, the LED display module and the main board it was mounted to.  The LED module consists a printed circuit board and custom plastic molding.  The custom molding includes a flame icon and a celsius symbol.

The icon is top right of the module

As with other Three-Five designs, the LED controller die was bonded directly to the custom LED PCB.  Three-Five Systems had extensive experience with wire bonding, as all LED displays require wire bonding.

Sadly I cannot find a picture of the display in the final unit, so if anyone has one, please feel free to send me a copy. 

Sunday, August 9, 1992

Lenze Industrial Inverter Display Panel

This was one of my first LCD designs.  Again I was responsible for the electrical, PCB, LCD and mechanical designs. This was a custom LCD display that was to fit into a plastic molding.  The LCD was a separate custom design that I put together including the metal bezel.

Custom LCD module on the main assembly

The electrical design for this was a little more complex.  Back in the 90s the LCD was driven but both X and Y drivers, mounted in die form under the LCD PCB.  The LCD itself was a custom design completed on AutoCad and manufactured by Three-Five Systems.

Completed Assembly

The remaining electrical design was conventional surface mount tech, as can be seen in the photos of the completed unit.  Some push buttons and LEDs completed the design.

The Complete Unit in situ

And this is what it looks like in the finished unit.  The module was designed for a number of different units, this is just one of the 

Friday, August 9, 1991

Custom LED Dot Matrix Display

This project was a stackable LED dot matrix display.  I don't have the drawings for this any more but this would have been about 25mm x 100mm (or 1"x4" for my American friends).  For this design I was again responsible for the electrical design, PCB layout and plastic molding design.

The Display Module

In order to make this stack correctly, the plastic molding had indents and protrusions to ensure alignment.  The photo below shows this detail.

This shows the location lugs

The electrical and PCB design featured a bank switched LED array, driven by a National 5450 LED driver, with the die directly mounted to the PCB (the black blob shown below) so part of the PCB design included the die layout and bonding diagram for the die placement. 
LED driver on the board

I believe this was in red but as for the purpose of the display, that is lost in the mists of time.

Monday, August 6, 1990

ABB Industrial Controller Display Panel

I worked at Three Five Systems for five years.  I was the only engineer in the UK office and in my time there I did the electronic design, PCB layout and the plastic molding design.

This assembly is the front panel for an industrial controller.  It consisted of 6 dual digit displays (14 segments), and a bar graph module. Both of these modules are custom assemblies, so I had three PCBs and two plastic moldings to design.

the complete assembly

The electronics to drive all of this consist of discrete transistors for bank switching, National 5450s for the LED driving, (remember this was the early 90s) and a couple of voltage regulators.

The PCB back side

I used PCAD to perform the PCB layout, and AutoCad for the plastic moldings.  However, to create these modules, Three-Five would use the silicon die and wire bond directly to the board. In the picture above, the black blobs are where the die is located.

The completed Module

I can't find a decent picture of the completed module, but here is a watermarked picture of the module.  

Thursday, August 17, 1989

Log Amp Control ASIC

Quantel was known for digital video in the late 80s and early 90s.  What a lot of people don't realize is that they also had a small team that designed electronics for niche military applications.  Quantel has had a fairly turbulent history and the military part of the company appears to have been spun off into Dynamic Signal Processing LTD.  The company does not appear to be in operation but references to its products can be found on its web site which at the time of writing is still up.

In my time at Quantel, my role was to create a mixed signal ASIC for stabilizing logarithmic amplifiers.  These log amps were used in video and radar applications.  The issue I had to solve was that log amps are inherently very unstable and given that these amplifiers are used in military applications, they had to work over a wide temperature range.  This compounds the issue with stability, making it far worse.

DVLA (Digital Video Logarithmic Amplifier)

The ASIC was defined to provide bias voltages for the amplifiers to stabilize them, based on a temperature measurement from a sensor on the amplifier.  Each amplifier was characterized in test and the appropriate bias voltage values were stored in an NVRAM.

Under normal operation, the ASIC ran a process that measured the temperature, compared the temperature value with the NVRAM to get the bias voltage, and output the bias voltage.  Inside the ASIC was a small processor (state machine), an I2C interface, some logic, DACs and ADCs.

The size of the ASIC was approx equivalent to about 4500 gates, and was to be rated to military specs; -55 to + 125C.  The ASIC was manufactured by Harris Semiconductor (in their fab in Melbourne FL I believe), designed on an Apollo computer design system, using Harris semiconductor FPGA text based design software. (no real graphical interfaces like there is today, or high level languages for definitions)

The only reference I can find to the design of the chip are on the google patents page and this page: Application EP90305332A.  These descriptions clearly show the slow speed mixed signal ASIC used for the control and compensation of the log amps.

Sunday, August 16, 1987

MBB105 Helmet Display

This project was a helmet mounted display for the MBB105 helicopter.  The display had some HUD function but was also slaved to the under mounted gun.  As the pilot's head moves, so the gun under the helicopter moves with it, and the optical system identifies hard edges of vehicles and buildings for targeting. 

MBB Bo 105

We take this stuff for granted today but back then (the late 80s) this was cutting edge military technology.  Now, your cell phone camera identifies faces, even as your subjects move around. It's basically the same technology, in a phone!

My part in all of this was again, the analog interfaces for the display itself. In this case the analogue card was shrunk down into a module, that would be mounted to the board. This meant we used all new devices, a lot of surface mount which was very new technology at the time. It presented a whole set of new challenges and that's what made this project fun.

Monday, August 10, 1987

Tornado E-Scope

 The Panavia Tornado was the primary strike aircraft for the royal air force in the 80s.  GEC Marconi was tasked with providing an avionics upgrade package that included a partial redesign of the e-scope


The e-scope is the display for the terrain following radar.  This radar enables the tornado to follow the contour of the land at low level. 

My role in this as a design engineer was to put together part of the display interface. This was a much smaller project than the C17 project for instance. 

Thursday, August 14, 1986

F5 Interface Card

A number of the Northrop F5's were used for training in the USA and were due an avionics refit. As a part of that refit, an interface between a radar system and HUD needed to be created.

This was a simple interface card to connect the radar system to the HUD.  Essentially the radar system had an XY analog output, but the signals were of the wrong polarity.  So the interface card buffered the signals and then inverted them, and buffered them out to the HUD.

F5E Tiger II

The design was a quick and easy one, compared to some of the others.  

Wednesday, August 6, 1986

C17 Globemaster HUD

Much of my time at GEC Marconi Avionics was spent on the C17 Globemaster project.  GEC were putting together an avionics package including the Head Up Display (HUD).  HUD systems back then were usually comprised of two parts; the optics assembly, mounted in the pilot's field of view, and the computer system that drives the optics.

C17 Globemaster

I don't know what HUD technology looks like now but back then, HUDs were based on CRTs with vector scanning. This required analog connections to CRT/Optical module, usually X, Y & Z where X and Y are the left/Right and up/down signal controls and Z is on/off.  

My role in this project was to take the digital data from the frame buffers, and turn them into analog signals. The challenge here was this had to be 14 bit accurate over the MIL-STD temperate range of -55C to +125C.  That is a tremendous amount of thermal problems.

Everyone gets a HUD
Back in those days, surface mount technology was just beginning to be a main stream thing, and the issue when dealing with extended temperature ranges was the surface mount components popping off the boards when subject to temperature extremes.

The temperature and accuracy challenges were eventually overcome and as we can see, the Globemaster is  extensively used, 25 years after I worked on it.

Thursday, July 31, 1986

Abrams M1A1 Laser Rangefinder

Way back in the 80s I worked for GEC Marconi Avionics.  I have no idea why we were asked to do this but we had to design the laser rangefinder receiver for the Abrams tank. Of course in a company that does military work you never get to see the big picture.

Abrams A1M1 (pic from Popular Mechanics)

The design challenge was that the return signal from the laser was so faint that thermal noise in the circuit would swamp the signal.  The design solution was a discrete low noise transistor amplifier, mounted on a peltier cooler to reduce the thermal noise. The output signal was then pushed through a logarithmic amplifier to provide a meaningful signal for the targeting systems.

It was an interesting project and as a new engineer, I found it fascinating and exciting.