SPRUJ79 November 2024 F29H850TU , F29H859TU-Q1
The SENT peripheral decodes serial data and performs a CRC check before the data is stored in the receive buffer. The decoding includes arranging the module before writing the data to the buffer, such as when a Fast Channel frame is received. The SENT frame format varies among different types of sensors, with the greatest number of nibbles being 11 (two CRC nibbles, eight data nibbles, and one status nibble).
The receive buffer for the SENT peripheral can be configured as a FIFO or a direct map. The received data is stored in the SENT_MEM location, with the offset depending on the receive frame and the mode chosen.
The FIFO mode is enabled by the FIFO_MODE bit in the RCFG2 register. In FIFO mode, the FIFO supports a depth of 24 values. This mode allows the host to be slow without causing data loss. Each sensor can store up to two data per frame, in addition to the time stamp. This allows 8 individual frames of data to be store using FIFO mode. The FIFO level is an indication of the number of 32-bit words available in the buffer, where each frame consists of three 32-bit words (timestamp, data 0, and data 1). This FIFO level can be used to generate an interrupt, if the level meets or exceeds the user configured threshold in RFIFO_TRIGLEV. See Section 42.5 for more details.
If the receiver FIFO receives a valid frame while the FIFO is full, the RFIFO_OVFERR bit in the RINTFLAG register is set and causes a receiver error interrupt. If the CPU or RTDMA try to read the FIFO when the FIFO is empty, the RFIFO_UNDFERR bit in the RINTFLAG register is set and causes a receiver error interrupt.
If the FIFO mode is disabled, the received data is directly mapped to a buffer at a specific address (see Section 42.8 for more details). In the direct map configuration, target devices can be triggered in any order. Upon a receive interrupt, the data is grabbed by the CPU from the specific memory location.