Conventional microcontroller (MCU)-based devices provide fixed services by executing statically compiled software in on-chip flash memory. In this paper, a newly designed on-demand remote code execution layer of the microcontroller bus architecture is proposed that enables seamless execution of the accessed instructions, which are dynamically loaded from the cloud side in the runtime. The proposed concept is applied to commercial MCUs based on ARM Cortex-M0 (TM), which are implemented using 0.18 um CMOS process with about a 10,000 2-input NAND gates overhead. The experimental results show that the proposed approach results in a 65% reduction of total chip area by eliminating on-chip flash memory, still requiring reasonable code access latency.