RA4M1 microcontroller used on Uno R4 supports 1.6V to 5.5V supply. ESP32 module supports only 3.3V. so, there is a regulator on the board to generate 3.3V from 5V. But the module and microcontroller are operating at different voltages. So, level translator is used for signals. I have a question, why couldn't RA4M1 be connected to 3.3V? This could have avoided level translators right? Are we getting some advantage because of 5V on RA4M1?
Hi @way2know.
The advantage is the alignment with the legacy of the 5 V AVR architecture Arduino boards. The UNO R4 is intended to be somewhat of a drop-in alternative for the classic UNO R3.
Even though more recently released boards are typically using 3.3 V levels, 5 V levels are still quite prevalent in the Arduino ecosystem. If you surveyed the modules and shields commonly used by the community, you might find that a significant portion of them are using 5 V levels.
1 Like
That looks reasonable. Considering that R3 is most used and if someone wants to move to R4 this makes it easy atleast w.r.t hardware atleast with a Wi-Fi add-on.
As architects, such a nice thought process put in here considering the ease of use of customers. Arduino rocks 
So, we can expect controllers on Arduino boards slowly moving to 3.3V supply in future..
It has already happened. Other than these two, all the new boards released by Arduino in the last 5 years have been 3.3 V. The last 5 V one was the Nano Every. Even before the Nano Every, Arduino started producing 3.3 V boards in 2012 with the Due and continued that trend with the Zero and MKR boards.
1 Like
I have invested good amount of money to procure two UNOR4 Boards for the purpose of learning the Architecture and Programming of 32-bit RA4M1 MCU. Now, I see it (the UNOR4) does not offer much compare to UNOR3 execpt WiFi and Bluetooth connectivity. My UNOR4 Learning Kits are almost lying idle, and I am spending time on ESP32 instead.
LOL, same here, I have some R4 boards gathering dust, meanwhile I am playing with much faster and cheaper boards.
When I looked for 5V ARM chips a while ago, there is a limited options, I only found some NXP and Infineon chips, but of course you still get lower drive current on IOs pins than true 5V cores.
I have to say, Arduino's choice of CPU to put on their new boards seems kind of random. They have picked SAM3X, SAMD21 and now RA4M1, when the most popular ARM CPU for DIYers seems to be STM chips like STMF103 and ESP series.
1 Like
It's about marketing. Marketing to all those who have 5V shields. There will be a 3.3V R5 using an ESP32E. The current UNO R4 is a mishmash of convolution and heterogenous complication; using a 240MHZ ESP32 (internally clocked by a PLL from 40MHZ XTL) just to perform the WiFi! Someone needs to teach the Arduino engineers the KISS principle. Most developers have switched over to 3.3V. In addition, the Renesas CPU is made from an ARM Cortex-M4 core. Like STM32 CPUs which also use ARM cores. Problem is the libraries are NOT compatible and Arduino has A LOT of work to do; for example the FastAcelStepper drivers for stepper motors need to be ported, the get-date-time (from NTP server) needs to be ported; anything that uses the underlying hardware must be re-coded; sound generators. Lastly and more important, why the Renesas CPU? Arduino OWNS part of Renesas, so they have a financial bias. I have moved on, and I now use the ESP32 and ESP32 modules. Especially the WEMOS D1 R2 which is an UNO clone with an ESP32-WROOM CPU that has WiFi. Espressif has undertaken a major project porting the ESP32 to the Arduino platform; which is really a dog if one must know. Ten years and it STILL takes two minutes to compile Blinky. Arduino needs to get on the ball and finish porting the BASIC FUNCTIONALITY of the libraries instead of creating gimmicky toys like the 96-LED array! After all, the UNO R4 has been out more than six months and it STILL doe snot have a basic time/date function; had to write my own! My Arduino UNO R4 will just be used as a bicycle taillight for now, or the tiniest political scrolling billboard.