More ARM1 processor reverse engineering: the priority encoder

full-encoder-labeled

In a previous post, Ken Shirriff reverse engineered the silicon in the ARM1 processor, this time he reverse-engineer the priority encoder in the ARM1 processor:

In this article, I reverse-engineer the priority encoder in the ARM1 processor. By examining the chip layout provided by the Visual ARM1 project, I have determined how this circuit works and created a schematic.
The ARM1 chip is the ancestor of the extremely popular ARM processors used in most smart phones. The ARM1 is a good choice for reverse engineering since it was designed in 1985 and its simple RISC silicon circuits are easier to understand than modern processors. This article jumps into the chip details; if you want an overview of the ARM1 internals, start with my first article on reverse engineering the ARM1.

More details at Ken Shirriff’s blog.

RF probe

Assembly-600

m0xpd writes:

Today I finally got round to building a nice little RF probe kit from Rex, w1rex, the Tuna King over at QRPme.
I took the well-executed PCB which – unusually for Rex – had through hole mounting for the components rather than the ‘Limerick’ construction that recently I’ve come to associate with him…
Following the excellent instructions, I whittled away the PCB at the business end, to make the probe easier to probe and poke into awkward places, then added the four components…

More details at m0xpd’s blog.

Fobble, a general purpose wireless breakout board

Fobble_4

Ken Boak  has been working on a general purpose wireless breakout board – Fobble:

As can be seen from the above picture it contains a number of key features:

  • A resident RFduino  Bluetooth Low Energy Module with ARM Cortex M0 processor
  • 2 layer pcb 50 x 50 mm format- with extended Arduino headers pin-out
  • An X-Bee footprint – with 0.1″ breakout headers – to add your own wireless module
  • Two push button switches – only 1 populated shown
  • Footprint for RGB 0505 LED
  • Detachable power and programmer section
  • Detachable side panels – to make 38 x 32 mm BLE Key Fob
  • 8 pin header to accept 1.3″ OLED display
  • 20mm coin cell or flat Li Po cell power – on rear of Fob pcb
  • Micro – USB connector for recharging Li Po
  • Side Prototyping areas – perforated in 0.1″ matrix
  • 7 pin and 5 pin headers to accept any RFduino accessory shields – for development work

Project info at Sustainable Suburbia blog.

Counting bits in hardware: Reverse engineering the silicon in the ARM1 processor

chip-labeled-bit

Ken Shirriff writes:

How can you count bits in hardware? In this article, I reverse-engineer the circuit used by the ARM1 processor to count the number of set bits in a 16-bit field, showing how individual transistors form multiplexers, which are combined into adders, and finally form the bit counter. The ARM1 is the ancestor of the processor in most cell phones, so you may have a descendent of this circuit in your pocket.

More details at Ken Shirriff’s blog.

Mullard 3-3 amplifier project (part 1)

24285038685_59b0262158_z

Dilshan Jayakody has published a new build, a Mullard 3-3 amplifier project:

Mullard 3-3 is quiet popular 3W tube amplifier introduced by Mullard Ltd in 1956. A schematic and design detail of this amplifier is available in “Mullard Circuits for Audio Amplifiers” book and in National Valve Museum article. This amplifier is based on EF86, EL84 vacuum tubes and EZ80 full wave rectifier tube. In this project we decided to construct this original Mullard 3-3 Amplifier with some slight changes and commonly available electronic components.
In our prototype we replace EZ80 tube with 400V 5A bridge rectifier which is commonly available in many electronic spare parts shops. Also we replace EL84 with 6P14P pentode and EF86 with 6J8 pentode. Both of these valves can directly use with this circuit and those values are available for lesser price than EL84, EF86 tubes.

Project info at Dilshan Jayakody’s blog.

Building a tracking generator

trackinggenerator

A how-to on building a tracking generator using off-the-shelf components by Kerry Wong:

In this blog post, I will show you how to build a 0 to 5.8 GHz tracking generator for the HP 8566B 100 Hz to 22 GHz spectrum analyzer using off-the-shelf components for under $100. Although this tracking generator is specifically designed for my HP 8566B spectrum analyzer, the method discussed below is applicable to pretty much any spectrum analyzer that has an LO output (typically the 1st LO).
A tracking generator, as its name implies, tracks the frequency of the spectrum analyzer’s sweeping oscillator (typically 1st LO) so that the tracking generator’s frequency output matches the center frequency of the bandpass filter in spectrum analyzer’s IF stage. Thus at any given moment, the spectrum analyzer sees the same frequency input as what it is currently sweeping at. The combination of a spectrum analyzer and a tracking generator is often referred to as a scalar network analyzer (SNA).

More details at Kerry Wong blog.

Check out the video after the break.

Monitoring woodstove temperature with a MAX31855 Quad Thermocouple BoosterPack

MAX31855 Quad Thermocouple

Spirilis over at the 43oh forum writes:

This was a project begun last winter in the hopes of having an array of thermocouples to monitor my old woodstove when operating it. Well, I never got around to finishing it, but I have a fancy new woodstove as of this fall, and I would love to monitor its temperature curves likewise!
This BoosterPack is fancied as a baseboard plugging underneath the LaunchPad, with four holes for mounting studs in case I ever decide to fix it inside a permanent enclosure (probably one made of aluminum due to the heat). I could have pushed the Thermocouple terminal blocks out a little further to fit more launchpads, as I feel this is a bit tight. I chose a Tiva-C LP for my pics because it fits nicely but the BoosterPack is designed with low-power features, contrary to the MAX31855’s own design.

Via 43oh.

CEmu, an open source TI-84 Plus CE / TI-83 Premium CE calculator emulator

0BJsPoG

Cemetechian MateoConLechuga and his team Jacobly, Adriweb, Lionel Debroux, Vogtinator have been working on a portable and open source TI-84 Plus CE/TI-83 Premium CE emulator – CEmu , that is available on Github:

Features

  • Portable emulation core written in C
  • Decent emulation accuracy yielding the ability to boot all of TI’s CE OS’s, browse around, execute self test successfully, and run programs
  • Portable GUI written in C++ using Qt (making it run on Windows, Mac OS X, Linux, Android, and iOS!
  • Docks/Tabs-based graphical UI (which you are able to customize)
  • Integrated setup wizard with ROM dumper for your calculator (there’s another one in TILP beta)
  • Simple debugger (read CPU registers, flags, ASIC state) and port monitor/writer
  • Animated (GIF) and still (PNG) screenshots

More info at Cemetech forum.

Reverse engineering the ARM1, ancestor of the iPhone’s processor

chip-labeled

Another great article from Ken Shirriff, this time on reverse engineering the ARM1:

Almost every smartphone uses a processor based on the ARM1 chip created in 1985. The Visual ARM1 simulator shows what happens inside the ARM1 chip as it runs; the result (below) is fascinating but mysterious.[1] In this article, I reverse engineer key parts of the chip and explain how they work, bridging the gap between the puzzling flashing lines in the simulator and what the chip is actually doing. I describethe overall structure of the chip and then descend to the individual transistors, showing how they are built out of silicon and work together to store and process data. After reading this article, you can look at the chip’s circuits and understand the data they store.

More details at Ken Shirriff’s blog.