2.5.1 Requirements

• Connect the external memory chosen as required in table “I/O Lines Usage vs. Operating Mode” in the section “External Memories” of the SAMA5D2 data sheet.
• Select the correct value for DDR_CAL depending on the memory used:
  • 21 kΩ for DDR2 and LPDDR1
  • 22 kΩ for DDR3
  • 23 kΩ for DDR3L
  • 24 kΩ for LPDDR2/LPDDR3
• Connect the DDR_VREF pin to VDDIOM/2
• SiP (System-in-Package) versions of the SAMA5D2 MPUs do not have a DDR_CAL pin. They do feature the ZQ pin necessary for the embedded DRAM, which should be connected to ground with a 240Ω resistor.

Refer to “DDR I/O Calibration” in the section “Memories” of the SAMA5D2 data sheet.