MCU Wars - Episode 3: 32-Bit Microcontroller Comparison

By Embedded Developer |


In this episode of MCU Wars, Ritesh Tyagi and Chris Anderson compare two 32-bit microcontrollers—the RX100 from Renesas, and the STM32 from STMicroelectronics. We chose these two devices because of the increasing demand for 32-bit microcontrollers in a variety of industries. Which one reigns supreme?



*Optimized for Low-Power*

According to Tyagi, Renesas has been “using a lot of proprietary technology to optimize the RX100 power consumption.” In order to do this, Renesas implemented a 130mm, low-leakage, low-power transistor flash process. “Compared to the RX600 or RX200 where we used their proprietary MONOS technology,” Tyagi explained, “we decided to use a completely different technology for the RX100.” Another differentiating factor is the redesign of the clock circuitry to offer a much faster wake-up. This allows the device to remain low-power in active and standby modes. The voltage regulator was built specifically for this device, offering very low power consumption. “Overall, there are a lot of different techniques and tricks that we employed to achieve a very low power standby current and active mode current,” Tyagi stated.

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*The STM32 L1 Toolchain*

When asked about the STM32 toolchain, Chris Anderson offered his preferences for ST products. Anderson explained, “ST offered a number of choices with quickstart guides for Embedded Workbench, but I settled on the Kiel Microvision 4.” Anderson stated that the Microvision had a number of example files that had all the source code needed to start tweaking in order to find something close to what he was trying to do. It also has a project manager compiler, an integrated debugger, and an abundance of example projects for dev kits of all the other major ARM vendors.


*Getting Started the RX100*

For the RX family, Renesas made a big company-wide push to launch the Eclipse- based IDE, called the e 2 studio. The RX100 will have the same toolchain based on the e 2 studio. Underneath that, Renesas offers a compiler as well as a compiler from IR and other third parties. “In fact,” Tyagi explained, “we are doing a pretty big joint promotion with International Rectifier where they start offering a 64K version of an IR workbench absolutely free.” The kit also comes with multiple sample projects and application examples. The board comes with a CD with a compiler and a debugger all within the kit. “I can guarantee,” Tyagi said, “that with the RX kit, you can be up and running within an hour.”



*Editor’s Pick*

Overall, the RX100 by Renesas offered significant low-power advantages over the STM32. The RX RDK Development Kit also offered significant features over the ST Discovery Kit, made possible by Renesas’ many partnerships in on-board components.

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  • by  David Zimmer (edited)
    Hi, To be honest I am quite surprise about this kind of approximate benchmark submit by Renesas . They used to provide us much more reliable and fair comparison vs. other MCU vendors. Below my comments. 1/ Coremark: shows STM32L1 at 2.93 (not 2.17) and RX111 at 3.08 2/Power consumption - RX111 real power consumption is 219uA/MHz not 100uA/MHz as state in DS (while{1} value in DS??) - gives RX111 at 98.52coremark. Renesas web site said 14coremark/mA => 98.52/14=7.03mA. Clk=32MHz => 7.03/32=> 219uA/MHz Coremark based! - STM32L1 DS state 240uA/MHz (dhrystone) at 32MHz not 290ua/MHz 3/ Other point - STM32L1 previous state wakeup time is 50uS not 2.6ms - STM32L1 pin count is 48p to 144p - USART nb is 5 not 3. - STM32L1 Built-in LCD driver 8x40 (RX100 ???) - STM32L1 Op-Amp and ultra-low-power comparator (RX100 ???) - STM32L1 Security feature: Clock system security, Flash JTAG fuse protection, ECC or AES 128-bit, 2watchdog … (RX100 ???) 4/ Tools: STM32L1 discovery is ~10$. The RX RDK dev kit (~100$) should be compare the STM32L1 development board. At the end of the day, Renesas has introduced a quite similar device with less feature, 3 years after the STM32L1 (introduced in 2010). BR, David.

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