Toshiba’s New MCUs Support Firmware Updates Without Pausing Operation

June 29, 2023 by Jake Hertz

The new family of microcontrollers is designed to enable over-the-air firmware updates without interrupting the execution of instructions.

Today, microcontrollers (MCUs) are the heart of almost all modern electronic devices. Since MCUs are largely responsible for executing the instructions that allow systems to perform their functions, memory capacity is one of the critical aspects that determine their performance.

This week, Toshiba announced a new set of MCUs that offer improved memory capacity and new functionality. 


Arm Cortex-M3 MCUs

Toshiba's new Arm Cortex-M3 MCUs feature 1 MB code flash memory and support firmware updates without interrupting MCU operation. Image courtesy of Toshiba

Understanding Microcontrollers and Memory

Microcontrollers are integrated circuits that consist of a processor core, memory, and programmable input/output peripherals. As mini-computers that exist on a single chip, MCUs are designed to implement electronic control and monitoring of larger systems. 


A standard MCU block diagram

A standard MCU block diagram

While microprocessors execute instructions and perform computation, MCUs place emphasis on interacting with external hardware modules to understand the state of the system and control it accordingly. One of the key components of a microcontroller is its memory, which stores the firmware, the software that provides low-level control for the device's specific hardware.

The greater the levels of memory in a microcontroller, the more sophisticated and functional the underlying hardware can be. Hence, memory can be a limiting aspect of the performance of a modern MCU.


Firmware Updates and Challenges

Since the underlying firmware of an MCU is so important, the ability to update that firmware in the field is a critical requirement of most systems. Overall, firmware updates are crucial for improving the functionality of a device, fixing bugs, and enhancing security.

However, one challenge with updating the firmware on an MCU is that it often requires the rest of the MCU to halt operations. Generally, firmware updates are resource-intensive operations, requiring a significant amount of processing power and memory to execute. 

For this reason, during an update, the MCU's resources are focused on writing the new firmware to memory, leaving little or no resources for the MCU to continue its normal operation. For real-time systems where every second of operation matters, devices must have enough memory to update the firmware without halting existing operations.


Toshiba's New MCUs Support Uninterrupted Firmware Updates

This week, Toshiba introduced a new series of MCU products, the M3H group (2), to the TXZ+ family of 32-bit microcontrollers. 

According to the datasheet, these new microcontrollers are equipped with a 120 MHz Arm Cortex-M3 core and feature a slew of integrated blocks, including a 12-bit ADC, an 8-bit DAC, a 1-channel comparator, and dedicated motor control circuitry. Most notable about the device, however, is its memory capabilities. 


Block diagram of the TMPM3H Group(2)

Block diagram of the TMPM3H group (2). Image courtesy of Toshiba

Specifically, Toshiba has expanded the code flash memory capacity in this generation from the previous 512 KB to 1 MB. The company also expanded the RAM capacity from 66 KB to 130 KB. According to Toshiba, this increase in memory now allows instructions to be read from one area of the device while the updated code from a firmware update is programmed into the other area in parallel. This unique feature enables the firmware rotation function, which is realized by the area swap function.

The M3H group products also come with a variety of interfaces, such as UART, I2C, an advanced encoder input circuit, and an advanced programmable motor control circuit. Toshiba hopes that these features will make the new family of MCUs suitable for a wide range of applications, including IoT, advanced functionality in motors, home appliances, and industrial equipment.