DMA Controlled Stimulation for Implantable Neurostimulators
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing implantable neurostimulation systems face challenges in power efficiency and redesign costs due to the use of conventional CPUs, which consume excessive power and require significant redesign for feature changes.
Innovation Solution
The implementation of a direct memory access (DMA) controlled stimulation system that includes two DMA channels and timers to manage stimulation events independently of the CPU, allowing the CPU to enter a low-power mode and reducing power consumption by selectively using different clock frequencies based on the required resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a programmable INS includes an ASIC for controlling functions, then control capability is improved, but design cost and redesign complexity increase significantly
Solution Approach 1:
The patent employs a universal microcontroller unit (MCU) that can perform multiple functions including generating stimulation waveforms, controlling DMA operations, and managing timing events. This single programmable device replaces what would otherwise require multiple specialized components, achieving high control capability while avoiding the redesign costs associated with ASICs. The MCU's programmable nature allows feature changes through software updates rather than hardware redesign.
2Adaptability or versatility
If a CPU is used to control neurostimulation functions, then programmability is improved, but power consumption increases significantly
Solution Approach 1:
The patent segments the control functions by introducing a DMA controller that operates independently from the CPU. The DMA controller handles time-critical tasks such as waveform generation and timing events, allowing the CPU to enter low-power modes between interruptions. This segmentation enables the system to maintain programmability through the CPU while significantly reducing average power consumption by offloading continuous operation to the more power-efficient DMA controller.
Solution Approach 2:
The system implements periodic action by using the DMA controller to handle routine stimulation delivery at fixed intervals, while the CPU remains in sleep mode and only activates periodically to handle higher-level control tasks. This periodic operation pattern allows the programmable CPU to maintain adaptability while consuming minimal power during non-critical periods.
3Measurement precision
If the CPU actively controls all stimulation events, then control precision is improved, but power consumption and processing overhead increase
Solution Approach 1:
The patent introduces the DMA controller as an intermediary between the CPU and the stimulation output circuitry. The DMA controller receives high-level commands from the CPU and autonomously handles the precise timing and waveform generation, ensuring control precision is maintained while the CPU consumes minimal power. This intermediary approach allows the CPU to set control parameters without being actively engaged in every stimulation event.
4Reliability
If an ASIC is designed for specific neurostimulation features, then feature performance is improved, but redesign cost increases when features change
Solution Approach 1:
The patent employs dynamic reconfigurability through a programmable microcontroller that can be updated with new features via software. Unlike fixed ASIC designs that require costly hardware redesigns, the MCU allows feature changes to be implemented dynamically through firmware updates. This maintains high feature performance through optimized algorithms while enabling flexible adaptation to new requirements without manufacturing redesign costs.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An implantable stimulation system (e.g., an implantable neurostimulation system (INS)) comprises memory including a first table and a second table. The first table stores blocks of stimulation event data corresponding to stimulation events that are to be performed during a period of time (e.g., a 0.5 sec. or 1 sec. period of time). The second table stores blocks of next stimulation event time data corresponding to the period of time. The implantable stimulation system also includes a direct memory access (DMA) controller including a first DMA channel and a second DMA channel. The first DMA channel selectively transfers one of the blocks stimulation event data from the first table to one or more registers that are used to control stimulation events. The second DMA channel selectively transfers one of the blocks of next stimulation event time data from the second table to a timer that is used to control timing associated with the stimulation events. In this manner, the DMA controller is able to control stimulation.