SLAU962A December 2025 – June 2026 MSPM33C321A , MSPM33C321A-Q1
Transmit FIFO
The TX FIFO is a 16-bit-wide, 4-location-deep, first-in first-out memory buffer. The CPU writes data to the FIFO by writing the QSPI Data Register TXDATA.DATA, and data is stored in the FIFO until it is read out by the transmission logic. Parallel data is written into the TX FIFO before serial conversion and transmission to the attached peripheral, respectively, through the IO pins is done. User or software is responsible to make valid data available to the FIFO as needed. The SPI can be configured to generate an interrupt or a DMA request when the FIFO is empty. The transmit FIFO has a TXFIFO_UNF interrupt to indicate a FIFO underflow condition.
Receive FIFO
The RX FIFO is a 16-bit-wide, 4-location-deep, first-in-first-out memory buffer. Received data from the serial interface is stored in the buffer until read out by the CPU or DMA, which accesses the read FIFO by reading the RXDATA register. Serial data is received through the IO pins. As the access pointer for the FIFO will be updated with each access, the data needs to be accessed by single transfers. With the FIFO fill level trigger signals located in the QSPISTAT register (TXFIFONF, TXFIFOE, RXFIFONF, RXFIFOE) the FIFO buffer allows an application to continuously stream serial data in one buffer while the application moves or process the data from the other buffer. If the FIFO is full and new data is written into the FIFO without reading data the RXFIFO overflow event is set.The receive FIFO has a RXFULL interrupt to indicate a FIFO full condition.