What is Microchip’s new PIC32A 32bit microcontroller architecture?
Does the world need another 32bit microcontroller architecture with the Microchip PIC32A?
ARM dominates the space, but RISC-V is the increasingly popular choice for open instruction sets. Microchip has pitched in with its own 32bit microcontroller architecture, the PIC32A.
This marks continuity with the company’s dsPIC real time digital signal controller (DSC) and highlights the differences between embedded hardware and software engineers, Joe Thomsen vice president of the digital signal controller business unit tells eeNews Europe.
“As we evolved the dsPIC family, we designed the dsPIC33C for real time control and dsPIC24 was the general purpose version we developed in parallel,” he said. The instruction set was still based on the original 8bit dsPIC16 with DSP extensions and then the 16bit dsPIC24 back in 2005. Now it has been up graded to a 32bit address space with the dsPIC33A.
The move to 32bits allows Microchip to add a 64bit floating point unit and two 72bit multiply accumulate (MAC) units to accelerate machine learning algorithms to the 200MHz PIC32A alongside the eight level deep working register sets that are familiar to the dsPIC developers.
“The PIC32-A is the general purpose version of the dsPIC33A and sits alongside the PIC32-C for the ARM Cortex-M devices and the PIC32-M for the MIPS cores. I’m core agnostic. The original ones are MIPS, the newer ones are ARM.”
So there are three 32bit microcontrollers:
- PIC32M, based on MIPS microAptiv and M4K cores
- PIC32C, based on the ARM Cortex-M0+, M7, M23 and M33 cores
- PIC32A, based on the dsPIC
All these have different instruction sets, and this is handled by the compiler technology and Microchip development tools such as MPLab X integrated development environment (IDE) and Harmony 32bit software development framework.
“They are highly similar but not binary compatible,” said Thomsen. “You can recompile code for a PIC24 to PIC32 and it still runs but it’s a 32bit machine. Moving from PIC16 to PIC18 we changed instruction set and again to PIC24 as the instruction words get longer and we add new instructions, for example there is a single clock read modify write as it’s still a Harvard architecture. The interrupt and clocking are still very similar so it will feel very similar to PIC24 developers, much so than the RISC-V processor.”
“We use the same compiler for MIPS, ARM and PIC32, and we are in MPLab and Harmony so anything that worked before works now,” he said. “The only place you would notice would be if you wrote assembly code.”
“But I started with PIC and I like PIC. There are advantage over ARM and MIPS which started out as software friendly with frameworks. These have abstraction layers that make life easy for software developers but tends hide the hardware functions.”
“PIC16 was really a bare metal design with a lot more access at the hardware level so I think hardware engineers will gravitate to the PIC32A and the software engineers will gravitate to the PIC32C,” he said.
PIC32A peripherals
“Don’t forget all the analog peripherals for the 32C are available for the 32A, the higher performance ADC and op amp, fast comparators, easy to use DACs.” The 12bit ADC operates at up to 40Msample/s and along with the 5 ns comparators and 100 MHz Gain Bandwidth Product (GBWP) op amps are aimed at data connection for intelligent edge sensing.
Alongside this, PIC32A also adds debug and security capabilities that are more common in the ARM ecosystem.
“We are adding real time trace and JTAG support so it will look more like an ARM debug environment. We are supporting secure debug, secure boot, this is critical.”
It adds integrated hardware safety and security features such as Error Code Correction (ECC) on Flash and RAM, Memory Built-In Self-Test (MBIST), I/O integrity monitor, clock monitoring, immutable secure boot and Flash access control features are designed to offer safe execution of software code within an embedded control system application.
But the main aim is to provide an upgrade path to PIC24 users to 32bit coding to work alongside the dsPIC33A digital signal controller.
“The PIC33A comes from PIC24 so people seem to like it, and we have customers that find it because it’s a PIC32,” says Thomsen.
www.microchip.com/en-us/products/microcontrollers-and-microprocessors/32-bit-mcus/pic32a
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