Implantable Backup Firmware Using Segmented RAM Failover
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges in mitigating adverse effects of memory failures during backup modes, particularly in Class III devices like pacemakers and ICDs, where RAM failures can disrupt essential therapy and communication functions.
Innovation Solution
The IMD incorporates a non-volatile memory (NVM) to store backup mode firmware and divides RAM into multiple blocks, using a counter to selectively switch to functional RAM blocks upon detection of malfunctions, ensuring continuous operation by incrementing the counter to alternate RAM blocks if failures occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RAM is used to store variables during backup mode, then the device can operate in backup mode with basic functions, but RAM failure can disrupt essential therapy and communication functions
Solution Approach 1:
The RAM is divided into multiple separate blocks (first RAM block, second RAM block) so that if one block fails, the other block can continue to store variables and maintain backup mode operation. This segmentation isolates the failure impact to a single block rather than the entire RAM system.
Solution Approach 2:
The system changes the operational parameter by switching between different RAM blocks based on their functional status. When a RAM block is detected as failed, the system transitions from using that block to using an alternative block, thereby adapting to the changed condition and maintaining reliability.
2Reliability
If the device switches between multiple RAM blocks, then reliability is improved through failure mitigation, but device complexity increases
Solution Approach 1:
The system performs self-diagnosis by detecting RAM block failures automatically and self-corrects by switching to functional blocks without external intervention. The processor monitors RAM block status and autonomously manages the switching between blocks, reducing the need for complex external control mechanisms.
Solution Approach 2:
The system implements a feedback mechanism where the status of each RAM block is continuously monitored and detected. Based on this feedback information about which blocks are functional or failed, the system dynamically adjusts its operation by selecting appropriate blocks for variable storage, creating a closed-loop control system that enhances reliability.
Data Source
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AI summary
Embodiments described herein relate to an IMD (100, 400) operating in a backup mode in a manner that mitigates against adverse effects of a memory failure. The IMD (100, 400) includes a NVM (122) that stores backup mode firmware, a RAM (124) that includes multiple separate RAM blocks (126), a processor (110, 420), and a counter (160). The processor (110, 420) executes the backup mode firmware to operate the IMD (100, 400) in accordance with a backup mode in response to detection of a malfunction that when detected should cause the IMD (100, 400) to operate in accordance with the backup mode. While the processor (110, 420) operates the IMD (100, 400) in accordance with the backup mode the processor (110, 420) stores and accesses variables in one of the RAM blocks (126). The counter (160) is selectively incremented and used to select which one of the RAM blocks (26) the variables are stored within while the processor (110, 410) executes the backup mode firmware to operate the IMD (100, 400) in accordance with the backup mode.