Cochlear Implant Systems todays challenges in embedded firmware - - PDF document

Cochlear Implant Systems

today’s challenges in embedded firmware design

December 7, 2009 René Roos

Cochlear Implant Systems?

Cochlear and CTC

• Cochlear Implant Systems for hearing impaired people
• First Cochlear implant, 1978, Melbourne Hospital
• First commercial, DSP-based processor: SPrint (1998)
• Current system: Nucleus 5 (2009)
• CTC: Cochlear’s R&D outside Australia

Cochlear Implant System

Complexity

Flexibility

Hybrid (CI + acoustic) CI Bone Anchored CI

Product diversity

1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 1 1 1 1 2 1 3 1 2 3 4 5 6 7 8 9 1 1 1 1 2 1 3 mild moderate

• mod. severe

severe profound A i r B

• n

e G a p ( d B H L ) S N H . L . ( d B H L ) deaf

total hearing loss Cochlear implants BAHA HA DACS Hybrid

Importance of firmware

• Manage system complexity

– Easy recipient ‘fitting’ – Programmable – Adjustable – Field upgrades – Hear Now. And Always

• Support product diversity & derivatives

– Platform development

Cochlear’s Champ

• Custom IC
• 4 Parallel DSPs
• uC
• 180 Mops
• Extremely low power consumption (few mW)

Hardware integration

• Limited amount of hardware releases
• ASIC Prototyping

– Modelsim – FPGA

• Product Prototyping

Software integration

• Firmware Integration

– uC – DSP

• Software Integration

– Device drivers – Clinical software – User devices

Sound processing research

• Simulink
• xPC Target

Quality

• Peer review

– Product code – Unit / System tests

• Coding guidelines

– MISRA-C

• Documentation
• Verification & validation

– Regression testing – Automation

• Code analyser tools

– Static – Dynamic

Looking into static code analysis (example)

Synchronous

int x, y, a[5] = {1, 2, 3, 4, 5}; void f1(void); void f2(void); void f1(void) { x = 10; f2(); } void f2(void) { y = a[x]; } int main() { f1(); return y; }

Asynchronous

int x, y, a[5] = {1, 2, 3, 4, 5}; typedef void (*EventHandler)(void); EventHandler handler; void scheduler(void) { while (handler) { handler(); } } void f1(void); void f2(void); void f1(void) { x = 10; handler = f2; } void f2(void) { y = a[x]; handler = 0; } int main() { handler = f1; scheduler(); return y; }

Regulatory

• Strict and clear procedures
• IEC 62304

– Segregation of software items – How to manage potential software failures – SOUP

Holy grail in supporting developments

• Looking for the perfect static analysis tool
• Formal code verification?
• Quantification of software risks?