Renesas RA - 1. Family Introduction

Hello there! After a long break I’m here again. And I want to introduce you to the new series of tutorials, which this time will be devoted to the RA family of Renesas Electronics Corporation.

Most of you will probably ask “What? Never heard of them.” And that’s actually ironic because Renesas is one of the biggest microcontroller suppliers in the world, especially in the automotive sector (proof: Renesas Electronics). The RA family is a relatively new one in their portfolio: it was just announced in 2019, and since then has already become quite popular among specialists.

In this series I want to tell you more about these microcontrollers and show how to use them in different applications.

Disclaimer. I’m new to the RA family as well, so I'll be learning them while writing these tutorials. Thus, I’d call this series “From the beginner to beginners”. But don’t worry, I have experience with a lot of other microcontrollers, so I have reasons to believe that I’ll manage with these ones as well. I will try to provide the content different from what you can find at the Renesas site (https://www.renesas.com/eu/en/products/microcontrollers-microprocessors/ra-cortex-m-mcus) but some basic information will be taken from there because basis is basis, and I can’t invent anything new when it comes from the foundational organization of the MCUs themselves.

Let’s first see what the RA microcontrollers are. According to the Renesas site the RA Family consists of Arm® Cortex®-M based MCUs. Which already sounds familiar for the majority of us. If one were to be asked “Which Arm® MCUs do you know?”, they would probably recall the STM32 family by STMicroelectronics, ATSAM family by Microchip (formerly Atmel), EFM32 family by Silicon Labs, XMC family by Infineon, or Tiva family by TI. OK, now we’re back on the ground, there is nothing we haven’t heard before, just another ARM® MCU with Renesas’ own personal twists.

The RA Family consists of several series, and it would be better to familiarize with them using the diagram from the Renesas site (Fig. 1)

As you can see the MCUs are divided into four series:

• RA2 is the low power series. It’s based on the relatively new Cortex-M23 core which provides advanced security features. The MCU frequency goes up to 60 MHz, the flash memory is up to 512 kB, and RAM is up to 64 kB. Among the peripherals there are USB Full-speed, CAN, and capacitive touch sensors. The RA2A1 group also provides a 24-bit SD-ADC and a 12-bit DAC which is quite a rare option for the ARM MCUs.
• RA4 is the balanced series which provides high performance with decent power consumption. It’s based on two Cortex-M cores: well-known Cortex-M4 and relatively new Cortex-M33. The MCU frequency goes up to 100 MHz, the flash memory is up to 1 MB, the RAM is up to 128 kB. The periphery is almost the same as for the RA2 series. Although the RA4W1 group has an additional built-in Bluetooth 5.0 transceiver.
• The RA6 series provides advanced performance. Like the RA4 series it’s also based on Cortex-M4 and Cortex M33 cores but the MCU frequency is increased to 240 MHz. The flash memory goes up to 2 MB, the RAM is up to 640 kB. The periphery includes all the modules from the RA4, and additionally has an external memory bus, Ethernet, graphic LCD controller, and USB High-speed. The RA6T1 group additionally has the enhanced peripheral for motor control, like high resolution PWM and advanced analog blocks.
• The RA8 series is still under development by the moment of writing this tutorial.

Also you may notice in Fig. 1 that the series are also divided into several groups depending on their functionality:

• RAxM - mainstream line;
• RAxL - low power line;
• RAxE - entry line;
• RAxA - rich analog line;
• RAxW - wireless line;
• RAxT - motor control line.

At the Renesas site you can get more detailed information about each series and group by clicking on it.

As you can see, Renesas provides a lot of quite interesting options for MCUs which can be used both in amatuer devices and commercial products. The benefits that I can personally see in the RA family, and that made me interested in them are:

• New Cortex-M23 and Cortex-M33 cores. To my shame, I still haven’t tried them even though they were announced in 2016. They claim to have an interesting feature called TrustZone, which divides the memory and peripherals into 2 zones: secure and non-secure. This approach limits the access to the crucial code and peripherals of the MCU. But we will discuss this topic in more detail when we get to it.
• RA2 and RA4 series have a supply voltage range of 1.6 - 5.5V. This is quite a rare option for the Cortex-M based MCUs. I can recall offhand only the ATSAMC series by Microchip that has the same range. The majority of Cortex-M based MCUs provide just 1.8 - 3.6 supply voltage range which is not enough in some applications.
• Rich analog periphery in RA2A1 group. Really, 24 bit Sigma-Delta ADC 16 bit SAR ADC, 12 bit DAC, operational amplifiers, along with the modern Cortex-M23 core - this is a very interesting set for the analog applications.
• Bluetooth 5.0 transceiver in RA4W1 group. It’s not a unique option among the MCUs, one can recall the nRF52 by Nordic Semiconductor, EFR32 by Silicon Labs, CC26xx by TI. But still, it’s interesting to see how it’s done in a new product.
• Wide set of advanced digital interfaces: USB High-speed and Full-speed, Ethernet, external memory bus, CAN, segment and graphical LCD, touch sensing.
• Development boards designed for each group of the RA family, each of which includes the target MCU along with the onboard Segger J-Link debugger, so you don’t need anything else to start the evaluation.
• Free e2 studio IDE provided by Renesas which also includes the graphic configuration tool and so-called Flexible Software Package (FSP) that includes functions which simplify the code writing. I will talk about the software in more detail next time.

For me the RA family is definitely worth learning. Moreover, as it’s not as popular as STM32 or ATSAM yet, you can find the RA MCUs freely at distributors or directly at Renesas which is a great advantage in the face of the current chip shortage.

Well, this is the basic information about the RA family that I found most important. As I said before, you can find detailed information at the Renesas site if you want something even more in-depth. In the next tutorial, I will show you how to install and configure the software required to work with the RA MCUs.