dPOD
Abstract -Embedded Debugging Personal Operable Device (dPOD)
The goal of this research project is to design, prototype, and document a complete Background Debug Mode (BDM) module for interface to the Motorola HCS12 family of microcontrollers, and develop a PC application to make use of the BDM protocol.
There are two major parts to this research project: (1) hardware, and (2) software. The hardware design and layout was tackled first, followed by designing a software protocol to interface a PC with the BDM protocol that the HCS12 microcontroller family understands. In parallel, portions of the software foundation that operates the BDM module was developed by L. Wyard-Scott while the hardware designs were documented and realized on a breadboard.
In the future, this module can be used as an on-chip debugger for any HCS12 microcontroller development and will prove useful to Electrical and Computer Engineering students and projects at the University of Alberta.
Project Overview
The Background Debugging Mode (BDM) provides an embedded system developer with the tools necessary to program and debug firmware programs on the target device. Implemented in hardware on the microcontroller, the protocol permits commands such as setting breakpoints, tracing, and memory and register modification. The BDM hardware module that is to be developed, herein known as the Embedded Debugging Personal Operable Device (POD) or dPOD, will adhere to the BDM protocol and the BDM standard cable. Thus, allowing all microcontrollers that utilize the BDM protocol to be controlled using the dPOD. This project will be based on BDM version 1.2, despite BDM version 4.0 already being distributed.
In order to meet the protocol requirements, specialized hardware that connects the PC to the target microcontroller will be created to allow this interfacing to occur. The dPOD is a protocol-translation system that receives RS232 serial signals after conversion to TTL-levels. The controller is constructed using a Programmable Integrated Circuit (PIC) running at 20 MHz and will receive the converted RS232 serial signals from a MAX232 chip.
