dbu

This project provides details on both the software and hardware for dbu, a cmsis-dap tool used for debugging ARM processors.

The dbu's main role is as a bootstrapping programmer for more complete multi-target development tools such as the fizzit pulsar.

Based on free-dap, dbu adds the SAML21 as a platform and introducs the capability to connect to multiple target CPU's. A single SAML21 can support up to 6 target CPUs.

How to use dbu

dbu is a component added to a target development board.

                   Target development board
                 .-------------------------------------------------------.
                 |                       Debug target CPUs               |
                 |                                                       |          
cmsis-dap       ---.   .------.         cmsis-dap swd ports              |  
hid host        USB|---| DBU  |------+-----+-----+-----+-----+-----.     |   
adapter         ---'   |      |-.    |     |     |     |     |     |     |   
                 |     `------' |    |0    |1    |2    |3    |4    |5    |   
                 |     SWD|     |  .-+-.  -+-.  -+-.  -+-. .-+-. .-+-.   |   
bootstrap       ---.      |     |  |CPU| |CPU| |CPU| |CPU| |CPU| |CPU|   |
programming      --|------'     |  |   | |   | |   | |   | |   | |   |   |
connector       ---'            |  `-+-' `-+-' `-+-' `-+-' `-+-' `-+-'   |
                 |              |    |     |     |     |     |     |     |
                 |              `----+-----+-----+-----+-----+-----'     |
                 |                        "printf" uarts                 |
                 |                                                       |
                 `-------------------------------------------------------'
		

To use dbu, add a SAML21 CPU and a USB connector to your development board and provide a method of bootstrapping the dbu firmware into the SAML21. (This repository includes a low-cost edge connector based adaptor as a bootstrap option.)

Additional features

The dbu software also implements a cmsis-dap vendor extension to control power delivery to the target.

It also supports the cmsis-dap UART commands to tunnel a uart debug message stream over the cmsis-dap HID interface. In other words dbu enables support for printf debugging of each target CPU over a single USB connection.

The detail

Follow these links for more information including instructions on building the software and hardware.

Building the software

Software user guide

Building the hardware