It’s been a while, but today has seen the launch of my latest project I’ve been involved in.
OSCAR is an adapter that converts an iPad 3/4 Retina display LCD to DisplayPort/Thunderbolt for use with your computer as an external monitor.
Don’t you just hate it when your printer refuses to accept a certain type of paper and it takes you 30 minutes to print one document? Well recently the family printer (an Epson PX710W) has suffered from this problem, refusing to accept any photo paper. This problem was driving me crazy recently when trying to print full A4 photos so I decided enough was enough and started investigating the problem.
The other day I said that the original oscilloscope hardware has been retired and a new version is in the design process. Below I have documented all the parts of the original hardware and have attached the schematics, board files and code.
After reading about counterfeit electronics in Military weapons, I never though that I would find any counterfeit products in any of the many devices I take apart. The other week however, this thought was disproved!
The school I attend won a Promethean ActiVote system which consists of 30 modules to vote on multiple choice answers with and a base station to connect all the modules to the computer via USB. The USB cable had been trapped in the box causing it to fracture due to the appalling quality of the cable. You can see from the photo to the right, the white ActiVote USB cable has no foil inside to shield the conductors, nor does it have the stress-releasing string that should stop fractures like this.
Anyway, opening up the unit I found a small 2layer PCB which contains an MCU, USB controller chip, wireless chip and some memory. One thing that struck me as odd was the strange black marks on (what was later found out to be) the MCU. The code on it has been scrubbed off, and a new one inked over the top of it! There was also a marking reading “PRS 10” engraved in a very dodgy manner. A little rubbing alcohol and scraping later, I managed to reveal a chip code that was slightly different to the one inked on top. You can see the markings in the picture below.
After some careful lighting and googling, we found the chip to be a Renesas H8S/2134 with a retail price of about $15. This obviously makes it worth counterfeiting with this high RRP. I cannot see that the chip is an old silicon revision and the module seems to work once I had soldered on a new cable.
The counterfeit electronics business is obviously massive and according to this slightly dated NASA report, the quality of the fakes varies massively. The quality of this fake was fairly bad with the new code inked on with water-soluble ink, but at least the chip is functional!
You can see in the picture the alpha revision oscilloscope that has now been superseded. It was designed in Eagle and consists of a 2layer PCB with a Xilinx Spartan 3AN FPGA, DDR SDRAM, Maxim ADC and Cypress FX2LP.
We went for a modular design in the end with separate input boards and USB board. This makes the system easier to debug by isolating different systems and makes it cheaper if any components need to be redesigned. We were very luck that there were very few mistakes in the PCBs so we only had to make one or two fixes.
Due to hardware restrictions (mainly the FPGA not being able to contain all the code) this design has now been retired and a new version is in the design process. The updated version now has a Spartan 6 FPGA at the centre, DDR3 memory, a 1GSPS ADC and Cypress FX3 which will provide SuperSpeed USB3 communications.
After deciding that the project could no longer be implemented on a 2layer PCB and the Eagle Free version only supports 2 layers, we had to look for other software. After doing some work experience with an electronics company, I was lucky enough to have a play with Cadence Allegro. I found that Altium Designer (a very similar product) seem to support a few student projects so I thought it was worth a try emailing them. Several weeks later I managed to score a year-long Altium Designer licence with an Altium Subscription free of charge! The acquisition of this software has meant the design process is a lot faster and easier, but understandably we cannot use the licence for commercial use.
I will post again soon (he says after not posting for 2 years!) with more HW&SW details and hopefully all the schematics.
It has been a long time and there have been several significant progressions!…
We has scraped the idea of using a PIC and are now using an FPGA that can run a lot faster, SRAM as a data buffer, a Cypress FX2 high speed USB controller and a whole host of analogue circuitry with multiplexers. We are still using the same ADC however. That part of the plan hasn’t changed!
We are currently finalising schematics, then will send the PCB designs off to be manufactured.
The end is in sight! This has turned out to be a project that has given us a vast amount of new knowledge. Now it’s time to share it!…
Just a quick update on the progress of the scope.
One difficulty we are finding is getting everything to work fast enough! We need a microcontroller that operates at 100MHz minimum to cope with the data throughput from the ADC! We are thinking of maybe using an ARM processor, as no PIC uC can cope with those speeds, but we haven’t decided yet.
This is turning out to be a challenging project!
More updates to follow soon.
Over the summer my electronics buddy Ali and I are building a 2 Channel 100MSPS Digital Oscilloscope.
The project is still in it’s fairly early stages but some details of the design so far follow:
It will use the MAX1198 ADC and MAX4105 op-amps
The MAX1198 samples the two input signals at 100MSPS at a resolution of 8bits.
The data will be filtered and buffered before going through the ADC and then the parallel output of the ADC will go into a PIC18F4550 to be sent through USB to a host computer.
More updates will follow soon, hopefully with some schematics and designs.
Today is the first day of the Atom Computing Blog. Updates are hopefully going to come at least weekly and will bring you the latest Electronics and Computer projects I embark on.