Sketch to use Arduino as I2C/SPI tool with Serial I/F.
Latest Sketch for Windows / Android app: sketch_I2C_SPI_bin_R13.ino
for Windows App ver. 5.0 or Later
for Android App ver. 3.0 or Later
Windows app and Android app are available.
Website (Japanese): https://ysin1128.hatenablog.com/entry/2020/02/23/173147
Website (English): https://ysin1128.hatenablog.com/entry/2020/03/07/165320