Toyomasa Watarai
Principal Application Engineer
Tokyo, Japan
Summary
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RockstarToyomasa Watarai is a Principal Application Engineer at Arm in Tokyo with 12 years of embedded systems experience, specializing in IoT platform and microcontroller bring-up. He has deep hands-on expertise porting and adapting Arm Mbed OS to constrained devices like the NXP LPC1114, implementing peripherals (PWM, I2C) and improving timing and flash programming logic. At Arm he has progressed from Staff to Principal roles, blending low-level firmware debugging with higher-level platform enablement for diverse MCU targets. His open-source contributions to high-profile projects such as ARMmbed/mbed-os and DAPLink include adding device support, fixing SWD target flows, and refactoring flash algorithms to enable sector erase—work that directly improves developer tooling for embedded ecosystems. Based in Tokyo, he combines pragmatic firmware craftsmanship with a focus on robust, resource-efficient designs that accelerate IoT productization. An understated strength is his knack for surfacing subtle hardware-software edge cases and turning them into reproducible, long-term fixes in upstream projects.
12 years of coding experience
Github Skills (16)
firmware10
cmsis10
arm10
embedded10
cortex-m10
c-language10
cprogramming-language10
abstraction-layer10
microcontroller10
sys10
hal10
pwm9
i2c9
rtos8
iot8
Programming languages (7)
Github contributions (5)
ARMmbed/DAPLink
Jul 2015 - Feb 2022
Role in this project:
Embedded Systems Engineer / IoT Developer
Embedded Systems Engineer / IoT DeveloperContributions:6 commits, 3 PRs, 11 comments in 6 years 8 months
Contributions summary:Toyomasa primarily contributed to adding support for the NXP LPC1114 device to the daplink project, including necessary modifications to the flash algorithm, scatter files, and clock control. They refactored flash programming logic for the LPC1114, enabling sector erase functionality. Additional contributions include fixing SWD target state calls and adding support for the STM32F407ve and Wio EMW3166 targets by updating configuration files.
firmwaremicrocontrollermbeddebugmcu
ARMmbed/mbed-os
Jul 2013 - Jun 2020
Arm Mbed OS is a platform operating system designed for the internet of things
Role in this project:Embedded Systems Engineer / IoT Developer
Embedded Systems Engineer / IoT DeveloperContributions:4 reviews, 151 commits, 33 PRs in 7 years
Contributions summary:Toyomasa primarily focused on porting and adapting the Arm Mbed OS for the NXP LPC1114 microcontroller, a platform designed for IoT applications. They addressed build and compile errors related to specific hardware targets, particularly the uARM toolchain. Additionally, the user implemented peripheral support, including PWM and I2C, and improved the us_ticker functionality for accurate timing on the LPC1114. These changes included fixing code for test cases and improving the software framework for resource-constrained devices.
kernelmbed-osoperating-systemlinuxmbed
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