Modern medical devices, like nebulizers, pulse oximeters, and glucose monitors, present a daunting number of design tradeoffs: portability, functionality, size, accuracy, power consumption, and cost, to name a few.
An overview of what is included within a basic wearable home health monitor. Image used courtesy of Microchip
Microchip is aiming to address these requirements with its newest PIC microcontroller family, which is betting on core-independent peripherals (CIPs) as a solution for juggling many circuit blocks.
Navigating the Many Circuit Blocks in Medical Devices
Portable medical devices require many different circuit blocks to create a useful system.
A block diagram of a typical portable medical device. Image used courtesy of Maxim Integrated
These may include a battery, power management circuitry, an analog front-end to interface with the application sensor, a microcontroller to supervise the system and perform calculations, a display, and sometimes even RF blocks.
How do engineers meet the many requirements of each of these systems?
Why Use Core-independent Peripherals?
One way companies are trying to navigate the many circuit-level decisions with medical devices is through MCUs that integrate core-independent peripherals (CIPs).
Generally speaking, MCUs work by leveraging various interrupts, which are defined in code by the programmer, allowing the CPU to observe the system and peripherals to respond to changes as needed. The CPU must constantly monitor its peripherals and execute interrupt instructions from memory, requiring expenditures in power and latency.
Block diagram of the new PIC18-Q40 family. Image used courtesy of Microchip
On the other hand, a CIP is an MCU peripheral that can handle various tasks without intervention from the CPU. These systems often rely on hardware-defined, as opposed to software-defined, interrupts and configurable logic cells to provide core-independence.
The benefits here are numerous. First, CIPs can provide lower power consumption since the CPU doesn’t need to be actively monitoring the system. This means the MCU can enter low-power states more frequently. CIPs also allow better performance, freeing up the CPU to focus on computation as well as the flash memory since CIPs need less code.
Finally, CIPs can offer higher integration levels, which can save space in a design and offer the increased functionality demanded from medical devices.
New PIC MCUs Bank on CIPs
Designed specifically for the medical industry, Microchip recently released its newest PIC microcontrollers set: the PIC18-Q40 family.
Various peripherals associated with the PIC18-Q40 family. Image used courtesy of Microchip
According to Microchip, the MCU boasts a wide variety of CIPs that are said to simplify the implementation of complex medical systems. Microchip says it has developed over twenty CIPs for its new family, including:
- PWM outputs
- Configurable logic cells
- 12-bit ADC
- Two 8-bit DACs
- Serial communication
The MCUs come in either 14- and 20-pin packages, integrating much of the functionality on-chip.
CIPs Increase Integration in Medical Devices
Microchip asserts these CIPs can increase functionality and performance of medical devices while also achieving low power and a small area. The company cites particular use cases in which these CIPs may benefit designers, including nebulizers and syringe pumps, both of which are said to benefit from the increased integration that the new MCU family offers.
Featured image used courtesy of Microchip