Hello guys, I am now developing a project which would like to use a PS4 controller control stm32. Since the USB shield with Bluetooth library already can be downloaded, I want to use Arduino as bridges to connect PS4 controller and stm32. So arduino needs to send signal to stm32. Because of the speed, I want to use spi( stm32 as master to generate clock and arduino as slave). But arduino must be spi master because USB host clip is a spi slave device. As a result, I cannot use Arduino as spi slave normally. Is there any method that I can program Arduino as spi slave? Can we turn 16u2 as a spi bridge?