Bi-phase Mark Code Asynchronous Decoder using SPI Block

Disclosed are techniques for using firmware and hardware blocks of a device to decode signals encoded by signal edge positioning within a data bit width, such as bi-phase mark space coding (BMC) used for encoding in-band communication of wireless charging systems. The first device may use general purpose I/O (GPIO) interrupts to detect the start of a packet. The firmware may synchronize and configure the clock of a serial peripheral interface (SPI) to oversample the signals. The SPI may store the sampled data into a buffer, freeing the firmware from having to expend processing cycles to detect the transitions of the data in real-time. The firmware may read the buffered samples to decode the packet data in a post-processing stage. The firmware may detect the end of the packet by polling and GPIO interrupts or based on the samples read from the buffer to stop the clock of the SPI.