SPRAD21F May   2022  – November 2024 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP , AM62A3 , AM62A3-Q1 , AM62A7 , AM62A7-Q1 , AM62P , AM62P-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
    1. 1.1 Application Note Usage Guidelines
      1. 1.1.1 Schematics Design Guidelines
      2. 1.1.2 Schematic Review Checklist
      3. 1.1.3 FAQ Reference for Application Note Usage Guidelines
    2. 1.2 AM62x Processor Family
      1. 1.2.1 AM625
      2. 1.2.2 AM623
      3. 1.2.3 AM625SIP
      4. 1.2.4 AM625-Q1
      5. 1.2.5 AM620-Q1
    3. 1.3 AM62Ax Processor Family
      1. 1.3.1 AM62A7
      2. 1.3.2 AM62A7-Q1
      3. 1.3.3 AM62A3
      4. 1.3.4 AM62A3-Q1
    4. 1.4 AM62Px Processor Family
      1. 1.4.1 AM62P
      2. 1.4.2 AM62P-Q1
  5. 2 Related Collaterals
    1. 2.1 Links to Commonly Available and Applicable Collaterals
      1. 2.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
      2. 2.1.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
      3. 2.1.3 AM62P / AM62P-Q1
    2. 2.2 Hardware Design Considerations for Custom Board
      1. 2.2.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
      2. 2.2.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
      3. 2.2.3 AM62P / AM62P-Q1
  6. 3 Processor Selection
    1. 3.1 Data Sheet Use Case and Version References in the Application Note
    2. 3.2 Device Selection and OPN
    3. 3.3 Peripheral Instance Naming Convention
    4. 3.4 Unused Peripherals
    5. 3.5 Device Ordering and Quality
    6. 3.6 Processor Selection Checklist
  7. 4 Power Architecture
    1. 4.1 Generating Supply Rails
      1. 4.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
        1. 4.1.1.1 Power Management IC (PMIC)
          1. 4.1.1.1.1 PMIC Checklist
          2. 4.1.1.1.2 Additional References
        2. 4.1.1.2 Discrete Power
          1. 4.1.1.2.1 DC/DC Converter
          2. 4.1.1.2.2 LDO
          3. 4.1.1.2.3 Discrete Power Checklist
      2. 4.1.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
        1. 4.1.2.1 PMIC
          1. 4.1.2.1.1 PMIC Checklist
        2. 4.1.2.2 Discrete Power
          1. 4.1.2.2.1 Discrete Power Checklist
      3. 4.1.3 AM62P / AM62P-Q1
        1. 4.1.3.1 PMIC
          1. 4.1.3.1.1 PMIC Checklist
        2. 4.1.3.2 Discrete Power
          1. 4.1.3.2.1 Discrete Power Checklist
    2. 4.2 Power Control and Circuit Protection
      1. 4.2.1 Load Switch (Power Switching)
        1. 4.2.1.1 Load Switch Checklist
      2. 4.2.2 eFuse IC (Power Switching and Protection)
  8. 5 General Recommendations
    1. 5.1 Processor Performance Evaluation Module (SK - Starter Kit)
      1. 5.1.1 Evaluation Module Checklist
    2. 5.2 Device-Specific (Processor-Specific, Processor-Family Specific) SK Versus Data Sheet
      1. 5.2.1 Notes About Component Selection
        1. 5.2.1.1 Series Resistor
        2. 5.2.1.2 Parallel Pull Resistor
        3. 5.2.1.3 Drive Strength Configuration
        4. 5.2.1.4 Data Sheet Recommendations
        5. 5.2.1.5 Processor IOs - External ESD Protection
        6. 5.2.1.6 Peripheral Clock Output Series Resistors
        7. 5.2.1.7 Component Selection Checklist
      2. 5.2.2 Additional Information Regarding Reuse of SK Design
        1. 5.2.2.1 Updated SK Schematic With Design, Review and CAD Notes Added
          1. 5.2.2.1.1 AM625 / AM623
          2. 5.2.2.1.2 AM625-Q1 / AM620-Q1
          3. 5.2.2.1.3 AM625SIP
          4. 5.2.2.1.4 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          5. 5.2.2.1.5 AM62P / AM62P-Q1
        2. 5.2.2.2 SK Design Files Reuse
          1. 5.2.2.2.1 Reuse of SK Design Checklist
    3. 5.3 Before Beginning the Design
      1. 5.3.1  Documentation
      2. 5.3.2  Processor Pin Attributes (Pinout) Verification
      3. 5.3.3  Device Comparison and IOSET
      4. 5.3.4  RSVD Reserved Pins (Signals)
      5. 5.3.5  Note on PADCONFIG Registers
      6. 5.3.6  Processor IO (Signal) Isolation for Fail-Safe Operation
      7. 5.3.7  Reference to Device-Specific SK
      8. 5.3.8  High-Speed Interface Design Guidelines
      9. 5.3.9  Recommended Current Source or Sink for LVCMOS (GPIO) Outputs
      10. 5.3.10 Connection of Slow Ramp Inputs or Capacitors to LVCMOS IOs (Inputs or Outputs)
      11. 5.3.11 Queries and Clarifications Related to Processor During Custom Board Design
      12. 5.3.12 Before Beginning the Design
      13. 5.3.13 Device Recommendations
  9. 6 Processor-Specific Recommendations
    1. 6.1 Common (Processor Start-Up) Connection
      1. 6.1.1 Power Supply
        1. 6.1.1.1 Supply for Core and Peripherals
          1. 6.1.1.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          2. 6.1.1.1.2 AM62P / AM62P-Q1
          3. 6.1.1.1.3 Additional Information
          4. 6.1.1.1.4 Processor Core and Peripheral Core Power Supply Checklist
          5. 6.1.1.1.5 Peripheral Analog Power Supply Checklist
        2. 6.1.1.2 Supply for IO Groups
          1. 6.1.1.2.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          2. 6.1.1.2.2 AM62P / AM62P-Q1
          3. 6.1.1.2.3 Additional Information
          4. 6.1.1.2.4 Supply for IO Groups Checklist
        3. 6.1.1.3 Supply for VPP (eFuse ROM Programming)
          1. 6.1.1.3.1 VPP Checklist
        4. 6.1.1.4 Supply Connection for Partial IO Mode (Low-Power) Configuration
          1. 6.1.1.4.1 Partial IO Used
          2. 6.1.1.4.2 Partial IO Unused
          3. 6.1.1.4.3 Data Sheet Reference for Power Sequence
          4. 6.1.1.4.4 Partial IO Low Mode Checklist
        5. 6.1.1.5 Additional Information
      2. 6.1.2 Capacitors for Supply Rails
        1. 6.1.2.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
        2. 6.1.2.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62P / AM62P-Q1
        3. 6.1.2.3 Additional Information
          1. 6.1.2.3.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          2. 6.1.2.3.2 AM62P / AM62P-Q1
        4. 6.1.2.4 Capacitors for Supply Rails Checklist
      3. 6.1.3 Processor Clock
        1. 6.1.3.1 Clock Inputs
          1. 6.1.3.1.1 High Frequency Oscillator (MCU_OSC0_XI / MCU_OSC0_XO)
          2. 6.1.3.1.2 Low Frequency Oscillator (WKUP_LFOSC0_XI / WKUP_LFOSC0_XO)
          3. 6.1.3.1.3 EXT_REFCLK1 (External Clock Input to Main Domain)
          4. 6.1.3.1.4 Additional Information
          5. 6.1.3.1.5 Clock Input Checklist - MCU_OSC0
          6. 6.1.3.1.6 Clock Input Checklist - WKUP_LFOSC0
        2. 6.1.3.2 Clock Outputs
          1. 6.1.3.2.1 Clock Output Checklist
      4. 6.1.4 Processor Reset
        1. 6.1.4.1 External Reset Inputs
        2. 6.1.4.2 Reset Status Outputs
        3. 6.1.4.3 Additional Information
        4. 6.1.4.4 Processor Reset Input Checklist
        5. 6.1.4.5 Processor Reset Status Output Checklist
      5. 6.1.5 Configuration of Boot Modes (for Processor)
        1. 6.1.5.1 Processor Boot Mode Inputs Isolation Buffers Use Case and Optimization
        2. 6.1.5.2 Boot Mode Selection
          1. 6.1.5.2.1 Notes for USB Boot Mode
        3. 6.1.5.3 Boot Mode Implementation Approaches
        4. 6.1.5.4 Additional Information
        5. 6.1.5.5 Configuration of Boot Modes (for Processor) Checklist
    2. 6.2 Board Debug Using JTAG and EMU
      1. 6.2.1 JTAG and EMU Used
      2. 6.2.2 JTAG and EMU Not Used
      3. 6.2.3 Additional Information
      4. 6.2.4 Board Debug Using JTAG and EMU Checklist
  10. 7 Processor Peripherals
    1. 7.1 Supply Connections for IO Groups
      1. 7.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
      2. 7.1.2 AM62P / AM62P-Q1
      3. 7.1.3 Supply Connections for IO Groups Checklist
    2. 7.2 Memory Interface (DDRSS (DDR4 / LPDDR4), MMCSD (eMMC / SD / SDIO), OSPI / QSPI and GPMC)
      1. 7.2.1 DDR Subsystem (DDRSS)
        1. 7.2.1.1 DDR4 SDRAM (Double Data Rate 4 Synchronous Dynamic Random-Access Memory)
          1. 7.2.1.1.1 AM625 / AM623 / AM625-Q1 / AM620-Q1
            1. 7.2.1.1.1.1 Memory Interface Configuration
            2. 7.2.1.1.1.2 Routing Topology and Terminations
            3. 7.2.1.1.1.3 Resistors for Control and Calibration
            4. 7.2.1.1.1.4 Capacitors for the Power Supply Rails
            5. 7.2.1.1.1.5 Data Bit or Byte Swapping
            6. 7.2.1.1.1.6 VTT Termination Schematics Reference
            7. 7.2.1.1.1.7 DDR4 Implementation Checklist
          2. 7.2.1.1.2 AM625SIP
          3. 7.2.1.1.3 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          4. 7.2.1.1.4 AM62P / AM62P-Q1
        2. 7.2.1.2 LPDDR4 SDRAM (Low-Power Double Data Rate 4 Synchronous Dynamic Random-Access Memory)
          1. 7.2.1.2.1 AM625 / AM623 / AM625-Q1 / AM620-Q1
            1. 7.2.1.2.1.1 Memory Interface Configuration
            2. 7.2.1.2.1.2 Routing Topology and Terminations
            3. 7.2.1.2.1.3 Resistors for Control and Calibration
            4. 7.2.1.2.1.4 Capacitors for the Power Supply Rails
            5. 7.2.1.2.1.5 Data Bit or Byte Swapping
            6. 7.2.1.2.1.6 LPDDR4 Implementation Checklist
          2. 7.2.1.2.2 AM625SIP
          3. 7.2.1.2.3 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62P / AM62P-Q1
            1. 7.2.1.2.3.1 Memory Interface Configuration
            2. 7.2.1.2.3.2 Routing Topology and Terminations
            3. 7.2.1.2.3.3 Resistors for Control and Calibration
            4. 7.2.1.2.3.4 Capacitors for the Power Supply Rails
            5. 7.2.1.2.3.5 Data Bit or Byte Swapping
            6. 7.2.1.2.3.6 LPDDR4 Implementation Checklist
      2. 7.2.2 Multi-Media Card/Secure Digital (MMCSD)
        1. 7.2.2.1 MMC0 - eMMC (Embedded Multi-Media Card) Interface
          1. 7.2.2.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
            1. 7.2.2.1.1.1 IO Power Supply
            2. 7.2.2.1.1.2 eMMC (Attached Device) Reset
            3. 7.2.2.1.1.3 Signals Connection
            4. 7.2.2.1.1.4 Capacitors for the Power Supply Rails
            5. 7.2.2.1.1.5 MMC0 (eMMC) Checklist for AM62x and AM62Ax
          2. 7.2.2.1.2 AM62P / AM62P-Q1
            1. 7.2.2.1.2.1 MMC0 Used
              1. 7.2.2.1.2.1.1 IO Power Supply
              2. 7.2.2.1.2.1.2 eMMC (Attached Device) Reset
              3. 7.2.2.1.2.1.3 Signals Connection
              4. 7.2.2.1.2.1.4 Capacitors for the Power Supply Rails
            2. 7.2.2.1.2.2 MMC0 Not Used
            3. 7.2.2.1.2.3 MMC0 (eMMC) Checklist for AM62P
          3. 7.2.2.1.3 Additional Information on eMMC PHY
          4. 7.2.2.1.4 MMC0 – SD (Secure Digital) Card Interface
        2. 7.2.2.2 MMC1/MMC2 – SD (Secure Digital) Card Interface
          1. 7.2.2.2.1 IO Power Supply
          2. 7.2.2.2.2 SD Card Supply Reset and Boot Configuration
          3. 7.2.2.2.3 Signals Connection
          4. 7.2.2.2.4 ESD Protection
          5. 7.2.2.2.5 Capacitors for the Power Supply Rails
          6. 7.2.2.2.6 MMC1 SD Card Interface Checklist
        3. 7.2.2.3 MMC1 / MMC2 SDIO (Embedded) Interface
          1. 7.2.2.3.1 IO Power Supply
          2. 7.2.2.3.2 Signals Connection
          3. 7.2.2.3.3 MMC2 SDIO (Embedded) Interface Checklist
        4. 7.2.2.4 Additional Information
      3. 7.2.3 Octal Serial Peripheral Interface (OSPI) and Quad Serial Peripheral Interface (QSPI)
        1. 7.2.3.1 IO Power Supply
        2. 7.2.3.2 OSPI / QSPI Reset
        3. 7.2.3.3 Signals Connection
        4. 7.2.3.4 Loopback Clock
        5. 7.2.3.5 Interface to Multiple Devices
        6. 7.2.3.6 Capacitors for the Power Supply Rails
        7. 7.2.3.7 OSPI / QSPI Implementation Checklist
      4. 7.2.4 General-Purpose Memory Controller (GPMC)
        1. 7.2.4.1 IO Power Supply
        2. 7.2.4.2 GPMC Interface
        3. 7.2.4.3 Memory (Attached Device) Reset
        4. 7.2.4.4 Signals Connection
          1. 7.2.4.4.1 GPMC NAND
        5. 7.2.4.5 Capacitors for the Power Supply Rails
        6. 7.2.4.6 GPMC Interface Checklist
    3. 7.3 External Communication Interface (Ethernet (CPSW3G), USB2.0, PRUSS, UART and Controller Area Network (CAN))
      1. 7.3.1 Ethernet Interface Using CPSW3G (Common Platform Ethernet Switch 3-Port Gigabit)
        1. 7.3.1.1  IO Power Supply
        2. 7.3.1.2  Ethernet PHY Reset
        3. 7.3.1.3  Ethernet PHY Pin Strapping
        4. 7.3.1.4  Ethernet PHY (and MAC) Operation and Media Independent Interface (MII) Clock
          1. 7.3.1.4.1 Crystal
          2. 7.3.1.4.2 Oscillator
          3. 7.3.1.4.3 Processor Clock Output (CLKOUT0)
        5. 7.3.1.5  MAC (Data, Control and Clock) Interface Signals Connection
        6. 7.3.1.6  External Interrupt (EXTINTn)
          1. 7.3.1.6.1 External Interrupt (EXTINTn) Checklist
        7. 7.3.1.7  MAC (Media Access Controller) to MAC Interface
        8. 7.3.1.8  MDIO (Management Data Input/Output) Interface
        9. 7.3.1.9  Ethernet MDI (Medium Dependent Interface) Including Magnetics
        10. 7.3.1.10 Capacitors for the Power Supply Rails
        11. 7.3.1.11 Ethernet Interface Checklist
      2. 7.3.2 Universal Serial Bus (USB2.0)
        1. 7.3.2.1 USBn (n = 0-1) Used
          1. 7.3.2.1.1 USB Host Interface
          2. 7.3.2.1.2 USB Device Interface
          3. 7.3.2.1.3 USB Dual-Role-Device Interface
          4. 7.3.2.1.4 USB Type-C®
        2. 7.3.2.2 USBn (n = 0-1) Not Used
        3. 7.3.2.3 Additional Information
        4. 7.3.2.4 USB Interface Checklist
      3. 7.3.3 Programmable Real-Time Unit Subsystem (PRUSS)
        1. 7.3.3.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
          1. 7.3.3.1.1 PRU Subsystem
          2. 7.3.3.1.2 PRUSS Checklist
        2. 7.3.3.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62P / AM62P-Q1
      4. 7.3.4 Universal Asynchronous Receiver/Transmitter (UART)
        1. 7.3.4.1 Universal Asynchronous Receiver/Transmitter (UART) Checklist
      5. 7.3.5 Controller Area Network (CAN)
        1. 7.3.5.1 Controller Area Network Checklist
    4. 7.4 On-board Synchronous Communication Interface (MCSPI, MCASP and I2C)
      1. 7.4.1 Multichannel Serial Peripheral Interface (MCSPI) and Multichannel Audio Serial Ports (MCASP)
        1. 7.4.1.1 MCSPI Checklist
        2. 7.4.1.2 MCASP Checklist
      2. 7.4.2 Inter-Integrated Circuit (I2C)
        1. 7.4.2.1 I2C Open-drain Output Type Buffer Checklist
        2. 7.4.2.2 I2C Emulated Open-drain Output Type Buffer Checklist
    5. 7.5 User Interface (CSIRX0, DPI, OLDI, DSI), GPIO and Hardware Diagnostics
      1. 7.5.1 Camera Serial Interface (CSI-Rx (CSI-2 port, CSIRX0 Instance))
        1. 7.5.1.1 CSIRX0 Used
        2. 7.5.1.2 CSIRX0 Not Used
        3. 7.5.1.3 CSI Checklist
      2. 7.5.2 Display Subsystem
        1. 7.5.2.1 Display Parallel Interface (DPI)
          1. 7.5.2.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62P / AM62P-Q1
            1. 7.5.2.1.1.1 IO Power Supply
            2. 7.5.2.1.1.2 DPI (Attached Device) Reset
            3. 7.5.2.1.1.3 Connection
            4. 7.5.2.1.1.4 Signals Connection
            5. 7.5.2.1.1.5 Capacitors for the Power Supply Rails
            6. 7.5.2.1.1.6 DPI Checklist
          2. 7.5.2.1.2 AM620-Q1
        2. 7.5.2.2 Open LVDS Display Interface (OLDI)
          1. 7.5.2.2.1 AM625 / AM623 / AM625SIP / AM625-Q1 and AM62P / AM62P-Q1
            1. 7.5.2.2.1.1 OLDI0 Used
              1. 7.5.2.2.1.1.1 IO Power Supply
              2. 7.5.2.2.1.1.2 OLDI (Attached Device) Reset
              3. 7.5.2.2.1.1.3 OLDI Interface Compatibility
              4. 7.5.2.2.1.1.4 Capacitors for the Power Supply Rails
              5. 7.5.2.2.1.1.5 OLDI Checklist
            2. 7.5.2.2.1.2 OLDI0 Not Used
            3. 7.5.2.2.1.3 Additional Information
          2. 7.5.2.2.2 AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
        3. 7.5.2.3 Display Serial Interface (DSI)
          1. 7.5.2.3.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          2. 7.5.2.3.2 AM62P / AM62P-Q1
            1. 7.5.2.3.2.1 DSITX0 Used
              1. 7.5.2.3.2.1.1 DSITX0 Checklist
            2. 7.5.2.3.2.2 DSITX0 Not Used
      3. 7.5.3 General Purpose Input/Output (GPIO)
        1. 7.5.3.1 Availability of CLKOUT on Processor GPIO
        2. 7.5.3.2 Connection and External Buffering
        3. 7.5.3.3 Additional Information
        4. 7.5.3.4 GPIO Checklist
      4. 7.5.4 On-board Hardware Diagnostics
        1. 7.5.4.1 Monitoring of On-board Supply Voltages Using Processor Voltage Monitors
          1. 7.5.4.1.1 Voltage Monitor Pins Used
            1. 7.5.4.1.1.1 Voltage Monitor Checklist
          2. 7.5.4.1.2 Voltage Monitor Pins Not Used
        2. 7.5.4.2 Internal Temperature Monitoring
          1. 7.5.4.2.1 Internal Temperature Monitoring Checklist
        3. 7.5.4.3 Connection of Error Signal Output (MCU_ERRORn)
        4. 7.5.4.4 High Frequency Oscillator (MCU_OSC0) Clock Loss Detection
    6. 7.6 Verifying Board Level Design Issues
      1. 7.6.1 Processor Pin Configuration Using PinMux Tool
      2. 7.6.2 Schematics Configurations
      3. 7.6.3 Connecting Supply Rails to Pullups
      4. 7.6.4 Peripheral (Subsystem) Clock Outputs
      5. 7.6.5 General Board Bring-up and Debug
        1. 7.6.5.1 Clock Output for Board Bring-Up, Test, or Debug
        2. 7.6.5.2 Additional Information
        3. 7.6.5.3 General Board Bring-up and Debug Checklist
  11. 8 Layout Notes (Added on the Schematic)
    1. 8.1 Layout Checklist
  12. 9 Custom Board Design Simulation
  13. 10Additional References
    1. 10.1 FAQ Covering AM6xx Processor Family
    2. 10.2 FAQs - Processor Product Family Wise and Sitara Processor Families
    3. 10.3 Processor Attached Devices
  14. 11Summary
  15. 12References
    1. 12.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
    2. 12.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
    3. 12.3 AM62P / AM62P-Q1
    4. 12.4 Common for all Processor Families
    5. 12.5 Master List of Available FAQs - Processor Family Wise
    6. 12.6 Master List of Available FAQs - Sitara Processor Families
    7. 12.7 FAQs Including Software Related
    8. 12.8 FAQs for Attached Devices
  16. 13Terminology
  17. 14Revision History
7.2.2.3.3 MMC2 SDIO (Embedded) Interface Checklist

General

Review and verify the following for the custom schematic design:

  1. Above section including relevant application notes and FAQ links.
  2. Pin attributes, signal description, and electrical specifications.
  3. Electrical characteristics, timing parameters, and any additional available information.
  4. Include a series resistor (0Ω) on the MMC2_CLK, placed as close to processor clock output pin as possible to dampen reflections. To prevent signal reflections and false clock transitions, a resistor may be required to eliminate possible signal reflections on MMC2_CLK, which is looped back internally on read transactions. Use 0Ω initially and adjust as required to match the PCB trace impedance.
  5. The MMC2 CLK, CMD, and DAT0..3 signal functions are implemented with SDIO buffers on pins powered from VDDSHV6, which operate at fixed 1.8V or 3.3V.
  6. The MMC2 SDCD and SDWP signal functions are implemented with LVCMOS buffers on pins powered from VDDSHV6 or VDDSHV0, which are operated at fixed 1.8V or 3.3V.
  7. The SDIO buffers are designed to support dynamic voltage change. When SDIO interface is used, connecting a fixed IO voltage (1.8V or 3.3V) is recommended.
  8. Processor IO buffers are off during reset. An external pullup is required for any of the processor or attached device IOs that can float. Pullups are needed on all data and command signals. Verify internal pullups are not configured when (improves noise immunity) external pullups are used. As a good design practice, a 47kΩ pullup is recommended for the pullup value to be within the SDIO specification, when internal pulls are enabled unexpectedly. With 47kΩ the resulting pull resistance will still be within the specified.
  9. Attached device reset implementation using processor IO. Verify the IO level compatibility and the connection of required pull (polarity is attached device dependent).

Schematic Review

Follow the below list for the custom schematic design:

  1. Required bulk and decoupling capacitors are provided. Compare with the SK schematics.
  2. Pull values used for the data, command and clock signals. Compare with the relevant SK.
  3. Series resistor value and placement on the clock output signal near to the processor.
  4. Implementation of reset logic.
  5. Supply rails connected follow the ROC and is a fixed supply.

Additional

  1. Verify required external ESD protection are provided for the interface signals when connected over an add-on card.
  2. Follow similar guidelines when using MMC1. When using MMC1, software changes are required because the SK only implements the SDIO interface on MMC2.
  3. There are no specific guidelines about SDIO devices providing or not providing internal pulls. The system designer implementing an embedded SDIO device must understand what the SDIO device provides and apply the appropriate external pull if not provided by the SDIO device. Most of the processor IOs buffers are off during reset and are not enabled until the system has booted and the software configures. To prevent floating inputs, use external pulls on any signals connected to the inputs of attached devices.
  4. For embedded SDIO application, the recommendation is to power IO supply rail from the same fixed 1.8V or 3.3V power source that is used to power the IOs of the SDIO attached device (an example is a Wi-Fi module).