booty 0.1.0

Bootloader application

Purpose

This code base is for creating a bootloader to be utilized for programming microcontroller flash memory. This program takes a hex file as the input and will parse that hex file and send it to the microcontroller bootloader over a serial UART (commonly referred to as a “serial port” or “COM port”).

The sole companion project to this is the bootypic project. Hopefully, more will follow.

Installation

The easiest way to install this utility is to pip install booty. Alternatively, you may download this repository, navigate to the root directory of the repository, and python setup.py install.

Running

Assuming that this is installed in your root python environment, it will create a command-line utility which can be directly invoked:

user ~$ booty --help
Usage: booty [OPTIONS]

Options:
  -h, --hexfile PATH      The path to the hex file  [required]
  -p, --port TEXT         Serial port (COMx on Windows devices, ttyXX on Unix-
                          like devices)  [required]
  -b, --baudrate INTEGER  Baud rate in bits/s (defaults to 115200)
  -l, --load              Load the device with the hex file
  -v, --verify            Verify device
  --help                  Show this message and exit.

Of course, to use the package, there are some options that need to be specified. The two most necessary options are the –hexfile and –port options. Additionally, either the –load or –verify should be specified or no action will take place. This is, after all, a loading and/or verification utility.

If –load and –verify are specified, the loading will take place first.

A common command to load and verify a device might look like this:

user ~$ booty -p COM20 --load --verify -hexfile "C:/path/to/my/hex.hex"

The utility will execute a series of commands and result in an output similar to this:

user ~$ booty -p COM20 --load --verify -hexfile "C:/path/to/my/hex.hex"
INFO:booty:Using provided hex file at "C:/path/to/my/hex.hex" to load and verify device
INFO:booty.comm_thread:platform set: dspic33ep32mc204
INFO:booty.comm_thread:version set: 0.1
INFO:booty.comm_thread:row length set: 2
INFO:booty.comm_thread:page length set: 512
INFO:booty.comm_thread:program length set: 21996
INFO:booty.comm_thread:max programming size set: 128
INFO:booty.comm_thread:application start address set: 4096
INFO:booty.comm_thread:device identification complete
INFO:booty:loading...
INFO:booty:device successfully loaded!
INFO:booty:verifying...
INFO:booty:device verified!

How it Works

All relevant information is stored on the microcontroller, meaning that the relevant data is stored at compile-time.

The programming takes place in three stages:

1. device polling - determines what the device is, the command set available, and the page erase and write sizes

2. erase/program - a series of erase/program cycles which write to the program memory of the microcontroller

3. read/verify - a complete read and verification of the user memory

Each of these sections can be clearly observed on a logic analyzer. The capture shown was using a dsPIC33EP32MC204 and takes 17.1s from first byte to last in order to transfer and verify 27.6kB of program data. There is probably some room to improve this a bit, but not much without impacting the compiled size of the device bootloader. Also keep in mind that flash erase and write cycles have minimum times associated with them.

A close up of page erase followed by a series of writes (4 writes of 128 instructions for each erase of 512 instructions):

A close up of reads: