説明

When choosing a flash device to incorporate with Zynq-7000 devices, it is important to consider the following logistical criteria:

• Is the device supported with the Xilinx tools?
• Will the device work with the Zynq device BootROM?
• Is the device supported with software like U-Boot and Linux?

In addition, there are design considerations which include:

• How many pins are required for a configuration method?
• How much flash memory is required?
• How fast can the Zynq-7000 device be configured?
• How difficult is it to manage the flash device?

Based on the logistical criteria, there are three categories of flash devices:

• Xilinx Tested and Supported Flash Devices - These devices meet the logistical criteria listed above.
  These devices receive regression testing with Xilinx tools and their use is fully supported by Xilinx Technical Support.
  
  
• Known to Work Flash Devices - These devices are not explicitly supported in the Xilinx tools, but have been known to work with Zynq-7000 devices.
  Many of these devices are programmed using U-Boot as an alternate programming method, but source changes to U-Boot might have to be made by users in order to configure that specific device.
  
  
• Unverified Flash Devices - These devices have not been tested in any way by Xilinx with Zynq-7000 devices.
  There are NO known issues (but possible limitations) for these devices.
  
  The user will be responsible for validating the flash on Zynq-7000, making necessary changes to U-Boot and configuring the device.
  
• For Guidelines on Xilinx Unverified QSPI Flash Devices, see (Xilinx Answer 62743)
• For Guidelines on Xilinx Unverified NAND Flash Devices, see (Xilinx Answer 63798)
• Incompatible Flash Devices - These devices will not work on Zynq-7000.
  
  

Note: Xilinx Technical Support will not be able to provide assistance with designs using "Known to Work" or "Unverified" flash devices.

Xilinx can only provide assistance for the devices listed as 'Xilinx Tested and Supported'.

ソリューション

QSPI

Benefits of QSPI:

• High performance - QSPI is the fastest configuration solution.
• Low Pin count - QSPI has the lowest pin count of the configuration solution options besides SD.
• Easy management - QSPI can be accessed as linear memory in Zynq-7000 devices. In addition, NO bad blocks management is required.

Downsides of QSPI:

• Low memory density - QPSI is only supported up to 16 MB in single linear mode or 32 MB in dual linear mode because linear QSPI controllers only support 3-byte addressing.
  Densities greater than 16 MB in single or 32 MB in dual need to be supported in I/O Mode.

Vendors

Configuration and Specifications

Xilinx Supported Devices

For QSPI flash devices with sector size greater than 64 KB and using SDK versions older than 2015.3, please refer to (Xilinx Answer 60539)

* 2013.04 is the U-Boot release number (U-Boot from April, 2013), not the Xilinx tool release.

** Xilinx Tools indicate the ISE (iMPACT) version. For Vivado and SDK Flash Programming version, refer to UG908 "Supported Flash memory devices for Zynq-7000 device configuration".

*** A patch to ISE14.7 and SDK 2013.3 may be required to program these flash devices in iMPACT and SDK.

The same patch works for both.

Refer to (Xilinx Answer 59275).

**** If a flash is marked as Xilinx Supported for a specific voltage (for example 1.8V), the equivalent flash at the other voltage (for example 3.3V) can be considered Known to Work.

See (Xilinx Answer 62743) for Guidelines on Xilinx Unverified QSPI Flash Devices.

NAND

Benefits of NAND:

• High Memory density - NAND is an inexpensive solution for large density devices.

Downsides of NAND:

• Lower device performance - Maximum bandwidth is less than QSPI.
• High pin count - NAND devices require more pins than QSPI.
• Difficult Management - NAND devices are hard to manage. Bad blocks are a regular concern which require design decisions on how bad blocks will be managed for a particular system setup.

Notes:

Only On-Die ECC and 1-bit ECC NAND devices can be used with Zynq-7000 SoC.

• In order to use On-Die ECC with Zynq-7000 SoC, the flash MUST be a MICRON and MUST support bit 3 (Enable/Disable ECC) in Feature Address 90h.

Only 1 chip-select NAND devices can be used with Zynq-7000 SoC.

Vendors

Micron on-die ECC NAND

Micron NAND devices typically require multi-bit ECC, which necessitates using only devices with on-die ECC support. Check the specific data sheet for on-die ECC support.

Configuration and Specifications

Xilinx Supported Devices

* 2013.04 is the U-Boot release number (U-Boot from April, 2013), not the Xilinx tool release.

** Xilinx Tools indicate the ISE (iMPACT) version. For Vivado and SDK Flash Programming version, refer to (UG908) "Supported Flash memory devices for Zynq-7000 device configuration".
**** If a flash is marked as Xilinx Supported for a specific voltage (for example 1.8V), the equivalent flash at the other voltage (for example 3.3V) can be considered Known to Work.

NOR

Benefits of NOR:

• Easy management - NOR can be accessed as linear memory in Zynq devices. In addition, bad blocks are not as much of a concern as, for example, NAND.

Downsides of NOR:

• High pin count - NOR requires nearly all of the 54 MIO pins.
• Low Density - NOR density is comparable to QSPI.

Vendors

Configuration and Specifications

Xilinx Supported Devices

* 2013.04 is the U-Boot release number (U-Boot from April, 2013), not the Xilinx tool release.

** Xilinx Tools indicate the ISE (iMPACT) version. For Vivado and SDK Flash Programming version, refer to UG908 "Supported Flash memory devices for Zynq-7000 device configuration".

eMMC:

The Zynq-7000 SoC is expected to work with eMMC devices because the protocol is the same as SD, but this has not been extensively verified. 

Users must be careful to meet all timing requirements as they might or might not comply with eMMC.

eMMC flash memories are NOT primary boot devices for Zynq-7000 family, but can be used as secondary boot device.

Refer to (UG585) Zynq-7000 SoC Technical Reference Manual for more details.

SD:

Benefits of SD:

• High density - SD has densities comparable to NAND.
• Easy Management - Device is generally managed as a file system. Bad blocks do not need to be managed in the user design.

Downsides of SD:

• Slow performance - SD is slower than QSPI
• Mechanical considerations - SD cards require a connector.
  eMMC devices are not primary boot devices but can be used as a secondary boot source.
  For details see Zynq-7000 SoC Software Developers Guide (UG821)

Configuration and Specifications:

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