Springboard Logic Analyzer

The goal of this project was to build a logic analyzer expansion for the Handspring Visor. A logic analyzer was chosen because the circuit and firmware to read the states of digital lines is relatively simple, and the focus of the project will be interfacing with the Visor. The intended user of this device is someone who does not require or cannot afford all the features of a desktop logic analyzer, or someone who must test a device in the field. At a minimum, the user should be able to test applications with low-cost microcontrollers.

Features

  • 16 digital inputs
  • Sampling at up to 20MHz
  • Optional trigger off of an 8-bit value
  • 256 sample pre-buffer when operating in trigger mode
  • 128k Sample Buffer
  • Graphical Interface through PalmOS software

The Microcontroller selected was an Atmel AT90LS8535 and development was done in assembly using Atmel's AVR Studio. The role of the microcontroller was to interpret the capture command sent by the PalmOS software, start the capture logic, wait for the trigger (if selected), and stop the capture logic once the appropriate number of samples was taken.

Several GAL16V8 programmable logic parts were used to implement the logic needed to operate storing the values into SRAM, and controlling the shared address and data busses for the Springboard interface.

The project was a success and the prototype hardware was completed. The software was not fully featured, but was able to demonstrate the features of the system adequately.

Logic Analyzer Screenshot

Logic Analyzer Screenshot

Logic Analyzer Prototype

Logic Analyzer Prototype