Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 11/11/2022
Public

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19.4.2.3. SPI Interrupts

The SPI controller supports combined interrupt requests, which can be masked. The combined interrupt request is the ORed result of all other SPI interrupts after masking. All SPI interrupts have active‑high polarity level. The SPI interrupts are described as follows: †

  • Transmit FIFO Empty Interrupt – Set when the transmit FIFO buffer is equal to or below its threshold value and requires service to prevent an underrun. The threshold value, set through a software‑programmable register, determines the level of transmit FIFO buffer entries at which an interrupt is generated. This interrupt is cleared by hardware when data are written into the transmit FIFO buffer, bringing it over the threshold level. †
  • Transmit FIFO Overflow Interrupt – Set when a master attempts to write data into the transmit FIFO buffer after it has been completely filled. When set, new data writes are discarded. This interrupt remains set until you read the transmit FIFO overflow interrupt clear register (TXOICR). †
  • Receive FIFO Full Interrupt – Set when the receive FIFO buffer is equal to or above its threshold value plus 1 and requires service to prevent an overflow. The threshold value, set through a software‑programmable register, determines the level of receive FIFO buffer entries at which an interrupt is generated. This interrupt is cleared by hardware when data are read from the receive FIFO buffer, bringing it below the threshold level. †
  • Receive FIFO Overflow Interrupt – Set when the receive logic attempts to place data into the receive FIFO buffer after it has been completely filled. When set, newly received data are discarded. This interrupt remains set until you read the receive FIFO overflow interrupt clear register (RXOICR). †
  • Receive FIFO Underflow Interrupt – Set when a system bus access attempts to read from the receive FIFO buffer when it is empty. When set, zeros are read back from the receive FIFO buffer. This interrupt remains set until you read the receive FIFO underflow interrupt clear register (RXUICR). †
  • Combined Interrupt Request – ORed result of all the above interrupt requests after masking. To mask this interrupt signal, you must mask all other SPI interrupt requests. †

Transmit FIFO Overflow, Transmit FIFO Empty, Receive FIFO Full, Receive FIFO Underflow, and Receive FIFO Overflow interrupts can all be masked independently, using the Interrupt Mask Register (IMR). †