The firmware improvement roadmap outlines strategies to decrease the time required to bring up new platforms and add new features, reduce negative customer feedback, and improve maintainability. It recommends reusing code, creating virtual devices, improving reliability through testing, making code more robust, and improving security. Following the strategies will help achieve goals of reducing costs and times while increasing customer satisfaction.

1. Firmware Improvement Roadmap
A step-by-step guide for improving firmware projects.

2. Date Author Reason Revision
2016-04-15 Scott Sweeting Broadened
Applicability
C
2014-12-16 Scott Sweeting Added goal details B
2014-12-02 Scott Sweeting Initial Release A

3. 1. Goals
1. Improve Lead-Time Of New Platform Bring-Up
Decrease the amount of time required to bring up new platforms. Quickly bringing up new platforms
improves time-to-market, potentially beating competitors to market, gaining market share and
increasing the on-sale lifetime.
2. Improve Lead-Time Of Major Functionality Addition/Subtraction
Decrease the amount of time required to implement new major functions. Quickly adding or removing
major features improves time-to-market, potentially beating competitors to market, gaining market
share and increasing the on-sale lifetime.
3. Improve Customer Feedback
Decrease amount and severity of negative customer feedback, reduce turn-around time in addressing
customer issues. This will increase customer satisfaction and improve sales through word-of-mouth.

4. 2. Strategies
1. Re-Use Code
Use a common codebase for all firmware projects. This will improve new platform lead-time by giving us
a head start on writing firmware – simply adapt existing firmware to a new platform by writing drivers
for new platform. Code that can quickly be adapted to different platforms also allows quick and
thorough component supplier evaluations.
2. Create Virtual Devices
To the maximum extent possible, use firmware code to develop host PC virtual projects to prototype
changes in host control software and nail down protocols.
3. Improve Reliability
Reliability is the quality that the device performs to the specifications (including implied specifications).
Use Continuous Improvement Testing
Verify each internal as well as external release according to the test plan & procedure. Importantly,
update the test plan & procedure with the test procedure of each issue as it is resolved.
Use Watchdog Timer
Using a watchdog timer will allow the device to reset itself when firmware freezes or RAM is corrupt.
Allows us to recover a device that cannot easily be cold-booted.
Use Long-Term Stability Testing
Running tests on units that are powered continuously for days, weeks, and month. This uncovers
memory allocation/freeing errors and timers that roll over after amounts of time greater than normal
bench testing. Coding issues uncovered with long-term stability testing: memory leaks, counter roll-
overs, mutexes that need to be around critical sections.
4. Improve Robustness
Robustness is the quality that the device handles unexpected inputs predictably and gracefully.
Improving robustness will allow us to diagnose and fix logical errors before they get to customers and
reduce time spent fixing errors that do make it to customers.
Use Comprehensive Testing
Test all possible inputs, not just ones in current use. Use comprehensive testing to verify conformance
to specifications.
Test Parameters To Each Function
Prevent null-pointer exceptions and design and input errors by checking each parameter to each
function.

5. Add Error Log To Fix Unreproducible Errors
Create an error log that can be retrieved by customers using host control software to be sent to
Engineering to allow us to fix errors that cannot be reproduced internally.
Bubble Up Errors, Handle Every Error
Fix design flaws by bubbling up errors to a function that can handle them. E.g., a function that does
division given a divisor as a parameter should return an error if the divisor is zero, and the function that
calls it should check for an error.
5. Improve Maintainability
Maintainability is the quality that firmware is quick and easy to modify. Improving maintainability will
increase our responsiveness to customer issues and decrease turn-around time on adding new features
and fixing bugs.
Develop A Coding standard
Coding standards give code consistency. Coding standards increase readability of code – the most
difficult aspect of firmware development. The coding standard will include friendly variable names. The
identifier “bufsz” is not more efficient than “bufferSize” when compiled to machine code. A “formula”
for naming variables and function reduces development time and developer mental load. E.g.:
“set_Mute(UNMUTE)” and “setNoDspChanges(void)” are inconsistent, whereas “MuteSet(UNMUTE)”
and “DspChangesSet(FALSE)” are consistent, thus easier to remember when being called from another
function.
Perform Code reviews
Code reviews disseminate news of changes across the team and concerned people from other teams,
increase group knowledge, and solicit constructive feedback.
Increase Modularity
Modularity is the ability to add or remove major functionality independently of other functions. Every
option will be moved into run-time configuration to allow us to test one firmware. We will separate data
from code so the same code can be downloaded to platform variants, reducing the complexity of
testing. A layer of abstraction will increase portability, allowing us to move from one platform to
another.
Use Object-Oriented Design
Object-oriented C code is efficient and allows for abstraction – for example, allowing us to change host
communication from Ethernet to serial, or to any other interface since the interface is very similar at a
high level, but very different at a low level. Object-orientated design facilitates high cohesion and low
coupling, and locality. High cohesion and low coupling simplifies design of complicated systems and
locality makes new code development and debugging easier.
Simplify Interrupt Service Routines
Remove everything but setting flags in interrupt service routines to increase responsiveness and
decrease number of events missed when handling interrupts.

6. 6. Improve Security
Add Granular access features
Determine the roles that access the device and allow for restrictions to only the areas each role needs.
Add public key validation of firmware.
Prevent unauthorized firmware from running on our hardware.
3. Conclusion
Following the firmware quality improvement strategies set out in this document will achieve the goals of
reducing cost and lead-time of introducing new hardware platforms, reducing cost and lead-time of
introducing new major functionality, and increasing customer satisfaction by eliminating issues before
they leave Engineering and improving our responsiveness to customer issues.