MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor 20-69
20.5.5.1 Address Calculation for the First-in Entry and Last-in Entry in the TX
FIFO
The memory address of the first-in entry in the TX FIFO is computed by the following equation:
First-in entry address = TXFIFO base + 4 (TXNXTPTR)
The memory address of the last-in entry in the TX FIFO is computed by the following equation:
Last-in entry address = TX FIFO base + 4*[(TXCTR + TXNXTPTR - 1) modulo TX FIFO depth]
where:
TX FIFO base: base address of TX FIFO
TXCTR: TX FIFO counter
TXNXTPTR: transmit next pointer
TX FIFO depth: transmit FIFO depth, implementation specific
20.5.5.2 Address Calculation for the First-in Entry and Last-in Entry in the RX
FIFO
The memory address of the first-in entry in the RX FIFO is computed by the following equation:
First-in entry address = TX FIFO base + 4*(POPNXTPTR)
The memory address of the last-in entry in the RX FIFO is computed by the following equation:
Last-in entry address = RX FIFO base + 4*[(RXCTR + POPNXTPTR - 1) modulo RX FIFO depth]
RX FIFO base: base address of RX FIFO
RXCTR: RX FIFO counter
POPNXTPTR: pop next pointer
RX FIFO depth: Receive FIFO depth, implementation specific
20.6 Revision History
Table 20-34. Changes added to MPC5553/5554 for Rev. 4.0 Release
Description of Change
Added the following bullet to the Features List:
• “Supports all functional modes from QSPI subblock of QSMCM (MPC500 family)”
Made the following change to the first paragraph of Section 20.1.4, “Modes of Operation”
• From: These modes can be divided into two categories; module-specific modes such as master, slave, and module disable
modes, and an MCU-specific mode (debug mode).
• To: These modes can be divided into two categories; module-specific modes such as master, slave, and module disable
modes, and a second category that is an MCU-specific mode: debug mode
Added a footnote to DSPI_A in the DSPI Detailed Memory Map table:
• “Only available in the MPC5554.”
Changed the NOTE in the DSPI_PUSHR register:
• From: “Only the TXDATA field is used for slaves.”
• To: “TXDATA is used in master and slave modes.”
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