Legacy Quad-SPI AXI Interface Configuration and Read Modes

Zynq UltraScale+ Device Technical Reference Manual (UG1085)

Document ID
UG1085
Release Date
2022-09-15
Revision
2.3 English

AXI read-burst transfers are translated into SPI flash read instructions that are sent to the Quad-SPI controller TXFIFO. The controller transmit logic retrieves the read instructions from the TXFIFO and passes them to the SPI flash memory device according to the SPI protocol.

The SPI read command is used in linear address mode by writing to the qspi.LQSPI_CFG [INST_CODE]. The supported read command codes and the recommended configuration register settings (qspi.LQSPI_CFG) are listed in Table: Quad-SPI Device Configuration Register Values. The optimal register values for Quad-SPI boot performance using a 33 MHz PS_REF_CLK are shown in Table: Quad-SPI Device Configuration Register Values. These Quad-SPI registers can be programmed in non-secure mode using the register initialization feature in the BootROM header which to speeds the loading of the FSBL/user code. A faster PS_REF_CLK requires adjusting the clock dividers.

The choice of operating mode depends on the capabilities of the Quad-SPI device. For the fastest performance, the I/O fast read modes use 4-bit parallel transfers for address and data. The quad output fast read uses 4-bit parallel transfers for data only. These are still faster than a serial-bit mode.

Table 24-6:      Quad-SPI Device Configuration Register Values

Instruction Code

LQSPI_CFG

LQSPI_CFG

COMMAND Register

Single

Dual

Micron

Winbond/Spansion

03h

0x80000203

0xe0000203

0x00002000

0x00002000

0Bh

0x8000020b

0xe000020b

0x00002820

0x00002820

3Bh

0x8000023b

0xe000023b

0x00002820

0x00002820

6Bh

0x8000026b

0xe000026b

0x00002820

0x00002820

BBh

0x800002bb

0xe00002bb

0x00001c20

0x00001810

EBh

0x800002eb

0xe00002eb

0x00001828

0x00001418

13h

0x88000213

0xe8000213

0x00002800

0x00002800

0Ch

0x8800020c

0xe800020c

0x00003020

0x00003020

3Ch

0x8800023c

0xe800023c

0x00003020

0x00003020

6Ch

0x8800026c

0xe800026c

0x00003020

0x00003020

BCh

0x880002bc

0xe80002bc

0x00002020

0x00001C10

ECh

0x880002ec

0xe80002ec

0x00001a28

0x00001618