The basic structure of the SERCOM serial engine is shown in Figure 1. Labels in capital letters are synchronous to the system clock and accessible by the CPU; labels in lowercase letters can be configured to run on the GCLK_SERCOMx_CORE clock or an external clock.
Figure 1. SERCOM Serial Engine
The transmitter consists of a single write buffer and a shift register.
The receiver consists of a one-level (I2C), two-level or four-level (USART, SPI) receive buffer and a shift register.
The baud-rate generator is capable of running on the GCLK_SERCOMx_CORE clock or an external clock.
Address matching logic is included for SPI and I2C operation.