ChaosKey: This is a hardware True Random Number Generator that attaches via USB.

This is a hardware True Random Number Generator that attaches via USB.

Version 0.3

This one uses the better noise source coupled with an op amp that provides 2MHz of bandwidth at a gain of 100, offering linear frequency response at a million samples per second.

A photo of prototype version 0.3:

Here’s a circuit diagram of the noise source:

Version 0.3 Hardware

• STM32F042 System-on-Chip
  • ARM Cortex-M0 MCU
  • 32k Flash
  • 6k RAM
  • USB 2.0 Full Speed
  • Crystal-less operation
• 20V noise source
  • AP3015A boost regulator
  • back-to-back 3904 transistor noise
• OPA356 op amp
  • 200MHz GBP

Version 0.2

This version uses a better noise source, but the single transistor amp designed to get from the 20mV noise source to a digital value doesn’t provide enough bandwidth, so the resulting signal seen by the CPU has poor frequency response.

Here’s a photo of prototype version 0.2:

Version 0.2 Hardware

• STM32F042 System-on-Chip
  • ARM Cortex-M0 MCU
  • 32k Flash
  • 6k RAM
  • USB 2.0
  • Crystal-less operation
• 20V noise source
  • AP3015A boost regulator
  • back-to-back 3904 transistor noise

Version 0.1

These are photos of prototype version 0.1:

Version 0.1 Hardware

• NXP LPC11U14 System-on-Chip
  • ARM Cortex-M0 MCU
  • 32k Flash
  • 6k RAM
  • USB 2.0
  • 8 12-bit analog inputs
  • I2C, SPI, async serial
  • digital I/O
• ZXRE1004 zener diode noise source
• MCP6L92 dual op-amp

Software

• Firmware Features
  • AltOS is written mostly in C with some ARM assembler
• Tools Used
  • gEDA for schematic capture and PCB layout
  • GCC compiler and source debugger
• Licenses
  • The hardware is licensed under the TAPR Open Hardware License
  • The software is licensed GPL version 2

Source:https://altusmetrum.org/