SPRADO3B December   2024  – September 2025 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
    1. 1.1 User's Guide Usage Guidelines
      1. 1.1.1 Custom Board Schematics Design Guidelines - References Used in the User's Guide
      2. 1.1.2 Processor Family Specific User's Guide
      3. 1.1.3 Schematic Design Guidelines
      4. 1.1.4 Schematic Review Checklist
        1. 1.1.4.1 Common Checklist for Use With All Schematic Design Guidelines and Schematics Review Sections
          1. 1.1.4.1.1 Custom Board Schematic Design Implementation Checklist Sub-Sections Description
      5. 1.1.5 FAQ Reference for User's Guide Usage During Schematic Self-review
    2. 1.2 AM62x Processor Family List of Processors
    3. 1.3 Updates to Schematics Design Guidelines and Schematics Review Checklist
  5. 2 Related Collaterals
    1. 2.1 Links to Commonly Referenced Collaterals During Custom Board Schematic Design
    2. 2.2 Hardware Design Considerations for Custom Board Design User's Guide
  6. 3 Processor-Specific Information
    1. 3.1 Selection of Processor OPN (Orderable Part Number)
    2. 3.2 Processor-specific Data Sheet Use Case and Version Referenced for User's Guide Edits
    3. 3.3 Peripheral Instance Naming Convention - Data Sheet and TRM
    4. 3.4 Processor Peripherals and IOs Connection When Not Used (Unused)
    5. 3.5 Ordering and Quality Information for AM62x Processor Familys
    6. 3.6 Checklist for Selection of Required Processor GPN (Generic Part Number) and OPN (Ordering Part Number)
  7. 4 Processor Power Architecture
    1. 4.1 Generating Processor-Specific and Peripherals (Attached Device) Supply Rails
      1. 4.1.1 AM625, AM623, AM620-Q1, AM625-Q1, AM625SIP Processor Family Power Architecture
        1. 4.1.1.1 Power Management IC (PMIC) Based Power Architecture
          1. 4.1.1.1.1 PMIC Based Power Architecture Checklist for TPS65219
          2. 4.1.1.1.2 Additional References
        2. 4.1.1.2 Discrete Power Devices (DC/DC, LDO) Based Power Architecture
          1. 4.1.1.2.1 Discrete DC/DCs
          2. 4.1.1.2.2 Discrete LDOs
          3. 4.1.1.2.3 Discrete Power Devices (DC/DC, LDO) Based Power Architecture Checklist
    2. 4.2 Processor Power Rails Supply Control, Sequencing and Supply Overload Protection
      1. 4.2.1 Load Switch (Processor Supply Rail Power Switching)
        1. 4.2.1.1 Load Switch (Processor Supply Rail Power Switching) 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 (Starter Kit) Checklist
    2. 5.2 Processor-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 Processor-specific Data Sheet Recommendations
        5. 5.2.1.5 Processor IOs Protection - Provision for External ESD Protection Devices
        6. 5.2.1.6 Peripheral Clock Outputs Series Resistor
        7. 5.2.1.7 Peripheral Clock Outputs Pulldown Resistor
        8. 5.2.1.8 Component Selection Checklist
      2. 5.2.2 Additional Information Regarding SK Design (Schematic, Board) and Reuse
        1. 5.2.2.1 Updated SK Schematic With Design, Review and CAD Notes Added
          1. 5.2.2.1.1 AM625, AM623 Processor Family
          2. 5.2.2.1.2 AM620-Q1, AM625-Q1 Processor Family
          3. 5.2.2.1.3 AM625SIP Processor Family
        2. 5.2.2.2 SK Design Files Reuse for Custom Board Design
          1. 5.2.2.2.1 SK Design Files Reuse for Custom Board Design - Checklist
      3. 5.2.3 SK Schematic Pages Sequencing (Based on Functions, Reuse) and SK Board Layout
    3. 5.3 Processor-Specific SDK
    4. 5.4 General Design Recommendations (to Know) Before Starting the Custom Board Design
      1. 5.4.1  Processor Documentation
      2. 5.4.2  Processor Pin Attributes (Pinout) Verification
      3. 5.4.3  Device Comparison, IOSET and Voltage Conflict
      4. 5.4.4  RSVD Reserved Pins (Signals)
      5. 5.4.5  Note on PADCONFIG Registers
      6. 5.4.6  Processor IO (Signal) Isolation for Fail-Safe Operation
      7. 5.4.7  Pin Connectivity Requirements and Reference to Processor-Specific SK
      8. 5.4.8  Custom Board High-Speed Interface Design Guidelines
      9. 5.4.9  Recommendation for LVCMOS (GPIO) Output Current Source or Current Sink
      10. 5.4.10 Connection of Slow Ramp Signal (Input) or Capacitor Load (Output) to Processor IOs
      11. 5.4.11 Processor and Processor Peripherals Design Related Queries During Custom Board Design
      12. 5.4.12 General Design Recommendations (to Know) Before Starting the Custom Board Design Checklist
      13. 5.4.13 Attached Devices Recommendations
  9. 6 Processor-Specific Recommendations for Power, Clock, Reset, Boot and Debug
    1. 6.1 Common (Processor Start-Up) Connections
      1. 6.1.1 Power Supply
        1. 6.1.1.1 Core and Peripherals Supplies
          1. 6.1.1.1.1 Power Supply Ramp (Slew Rate) Requirement and Dynamic Voltage Scaling
          2. 6.1.1.1.2 Additional Information
          3. 6.1.1.1.3 Processor Core and Peripheral Core Power Supply Checklist
          4. 6.1.1.1.4 Peripheral Analog Power Supply Checklist
        2. 6.1.1.2 IO Supply for IO Groups
          1. 6.1.1.2.1 Additional Information
          2. 6.1.1.2.2 IO Supply for IO Groups Checklist
        3. 6.1.1.3 Supply for VPP (eFuse ROM Programming)
          1. 6.1.1.3.1 Supply for VPP Checklist
        4. 6.1.1.4 Supply Connection for Partial IO (Low Power) Mode Configuration
          1. 6.1.1.4.1 Partial IO Mode Functionality
          2. 6.1.1.4.2 Partial IO Low Power Mode When Used
          3. 6.1.1.4.3 Partial IO Low Power Mode When Not Used
          4. 6.1.1.4.4 Processor-specific Data Sheet Reference for Power Sequence
          5. 6.1.1.4.5 Partial IO (Low Power) Mode Checklist
        5. 6.1.1.5 Additional Information
      2. 6.1.2 Capacitors for Supply Rails
        1. 6.1.2.1 AM625, AM623, AM620-Q1, AM625-Q1, AM625SIP Processor Family
        2. 6.1.2.2 Additional Information
        3. 6.1.2.3 Capacitors for Supply Rails Checklist
      3. 6.1.3 Processor Clocks (Inputs / Outputs)
        1. 6.1.3.1 Clock Inputs
          1. 6.1.3.1.1 MCU_OSC0 (High Frequency) Clock (Internal Oscillator) or LVCMOS Digital Clock (External Oscillator)
          2. 6.1.3.1.2 WKUP_LFOSC0 (Low Frequency) Clock (Internal Oscillator) or LVCMOS Digital Clock (External Oscillator)
          3. 6.1.3.1.3 EXT_REFCLK1 (External Clock Input to MAIN Domain)
          4. 6.1.3.1.4 Clock Input Checklist - MCU_OSC0
          5. 6.1.3.1.5 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 Inputs Checklist
        5. 6.1.4.5 Processor Reset Status Outputs 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 Configuration
          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 Custom Board Debug Using JTAG and EMU
      1. 6.2.1 JTAG Interface and EMU Signals When Used
      2. 6.2.2 JTAG Interface and EMU Signals When Not Used
      3. 6.2.3 Additional Information
      4. 6.2.4 Custom Board Debug Using JTAG and EMU Checklist
  10. 7 Processor Peripherals Power, Interface and Connections
    1. 7.1 Supported Processor Cores and MCU Cores
    2. 7.2 Supply Connections for IO Supply for IO Groups
      1. 7.2.1 AM625, AM623, AM620-Q1, AM625-Q1, AM625SIP IO supply
      2. 7.2.2 Supply Connections for IO Supply for IO Groups Checklist
    3. 7.3 Memory Interface (DDRSS (DDR4/LPDDR4), MMCSD (eMMC/SD Card/SDIO), OSPI/QSPI and GPMC)
      1. 7.3.1 DDR Subsystem (DDRSS)
        1. 7.3.1.1 DDR4 SDRAM (Double Data Rate 4 Synchronous Dynamic Random-Access Memory)
          1. 7.3.1.1.1 AM625, AM623, AM620-Q1, AM625-Q1 Processor Family
            1. 7.3.1.1.1.1 Memory Interface Configuration
            2. 7.3.1.1.1.2 Routing Topology and Connection of Memory Terminations
            3. 7.3.1.1.1.3 Resistors for DDRSS Control and Calibration
            4. 7.3.1.1.1.4 Capacitors for the Power Supply Rails
            5. 7.3.1.1.1.5 Data Bit or Byte Swapping
            6. 7.3.1.1.1.6 DDR4 Implementation Checklist
            7. 7.3.1.1.1.7 DDR4 VTT Termination Implementation Schematic Reference
          2. 7.3.1.1.2 AM625SIP Processor Family
        2. 7.3.1.2 LPDDR4 SDRAM (Low-Power Double Data Rate 4 Synchronous Dynamic Random-Access Memory)
          1. 7.3.1.2.1 AM625, AM623, AM620-Q1, AM625-Q1 Processor Family
            1. 7.3.1.2.1.1 Memory Interface Configuration
            2. 7.3.1.2.1.2 Routing Topology and Connection of Memory Terminations
            3. 7.3.1.2.1.3 Resistors for DDRSS Control and Calibration
            4. 7.3.1.2.1.4 Capacitors for the Power Supply Rails
            5. 7.3.1.2.1.5 Data Bit or Byte Swapping
            6. 7.3.1.2.1.6 DDRSS Signals Pin (Package) Delay Information
            7. 7.3.1.2.1.7 LPDDR4 Implementation Checklist
          2. 7.3.1.2.2 AM625SIP Processor Family
            1. 7.3.1.2.2.1 AM625SIP LPDDR4 Connection Checklist
      2. 7.3.2 Multi-Media Card/Secure Digital (MMCSD)
        1. 7.3.2.1 MMC0 - eMMC (Embedded Multi-Media Card) Interface
          1. 7.3.2.1.1 AM625, AM623, AM620-Q1, AM625-Q1, AM625SIP Processor Family
            1. 7.3.2.1.1.1 IO Power Supply
            2. 7.3.2.1.1.2 eMMC Interface Signals Connection
            3. 7.3.2.1.1.3 eMMC (Attached Device) Reset
            4. 7.3.2.1.1.4 Capacitors for the Power Supply Rails
            5. 7.3.2.1.1.5 MMC0 (eMMC) Checklist
          2. 7.3.2.1.2 Additional Information on eMMC PHY
          3. 7.3.2.1.3 MMC0 – SD (Secure Digital) Card Interface
        2. 7.3.2.2 MMC1/MMC2 – SD (Secure Digital) Card Interface
          1. 7.3.2.2.1 IO Power Supply
          2. 7.3.2.2.2 Signals Connection
            1. 7.3.2.2.2.1 MMC1 Signals Used for SD Card Interface (Recommended)
            2. 7.3.2.2.2.2 MMC2 Signals Used for SD Card Interface
            3. 7.3.2.2.2.3 Additional Information
          3. 7.3.2.2.3 SD Card Power Supply Switch EN Reset Logic
          4. 7.3.2.2.4 External ESD Protection for the SD Card Interface Signals
          5. 7.3.2.2.5 Capacitors for the IO Supply for IO Groups Supply Rails
          6. 7.3.2.2.6 SD Card Interface (MMC1) Checklist
        3. 7.3.2.3 MMC1/MMC2 SDIO (Embedded) Interface
          1. 7.3.2.3.1 IO Power Supply
          2. 7.3.2.3.2 Signals Connection
          3. 7.3.2.3.3 SDIO (MMC2 Recommended, Embedded) Interface Checklist
        4. 7.3.2.4 Additional Information
      3. 7.3.3 Octal Serial Peripheral Interface (OSPI) or Quad Serial Peripheral Interface (QSPI)
        1. 7.3.3.1 IO Power Supply
        2. 7.3.3.2 Signals Connection
        3. 7.3.3.3 OSPI/QSPI Device Reset
        4. 7.3.3.4 Loopback Clock
        5. 7.3.3.5 Interface to Multiple (Attached) Devices
        6. 7.3.3.6 Capacitors for the Power Supply Rails
        7. 7.3.3.7 OSPI0 or QSPI0 Peripheral Interface Implementation Checklist
      4. 7.3.4 General-Purpose Memory Controller (GPMC)
        1. 7.3.4.1 IO Power Supply
        2. 7.3.4.2 GPMC Interface
        3. 7.3.4.3 Signals Connection
          1. 7.3.4.3.1 GPMC NAND
        4. 7.3.4.4 Memory (Attached Device) Reset
        5. 7.3.4.5 Capacitors for the Power Supply Rails
        6. 7.3.4.6 GPMC Interface Checklist
    4. 7.4 External Communication Interface (Ethernet (CPSW3G0), USB2.0, PRUSS, UART and MCAN)
      1. 7.4.1 Ethernet (MAC) Interface
        1. 7.4.1.1 Common Platform Ethernet Switch 3-port Gigabit (CPSW3G0)
          1. 7.4.1.1.1  IO Power Supply
          2. 7.4.1.1.2  MAC (Data, Control and Clock) Interface Signals Connection
          3. 7.4.1.1.3  EPHYs Reset
          4. 7.4.1.1.4  Ethernet PHY (and MAC) Operation and Media Independent Interface (MII) Clock
            1. 7.4.1.1.4.1 Crystal Used as Clock Source for Processor and EPHYs
            2. 7.4.1.1.4.2 External Oscillator Used as Clock Source
            3. 7.4.1.1.4.3 Processor Clock Output (CLKOUT0)
          5. 7.4.1.1.5  Ethernet PHY Pin Strapping
          6. 7.4.1.1.6  External Interrupt (EXTINTn)
            1. 7.4.1.1.6.1 External Interrupt (EXTINTn) Checklist
          7. 7.4.1.1.7  MAC (Media Access Controller) to MAC Interface
          8. 7.4.1.1.8  MDIO (Management Data Input/Output) Interface
          9. 7.4.1.1.9  Ethernet MDI (Medium Dependent Interface) Including Magnetics
          10. 7.4.1.1.10 Capacitors for the Power Supply Rails
          11. 7.4.1.1.11 Ethernet Interface Checklist
      2. 7.4.2 Universal Serial Bus (USB2.0)
        1. 7.4.2.1 USBn (n = 0-1) Interface When Used
          1. 7.4.2.1.1 USB Interface Configured as Host
          2. 7.4.2.1.2 USB Interface Configured as Device
          3. 7.4.2.1.3 USB Interface Configured as Dual-Role-Device
          4. 7.4.2.1.4 USB Type-C
        2. 7.4.2.2 USBn (n = 0-1) Interface When Not Used
        3. 7.4.2.3 Additional Information
        4. 7.4.2.4 USB Interface Checklist
      3. 7.4.3 Programmable Real-Time Unit Subsystem (PRUSS)
        1. 7.4.3.1 AM625, AM623, AM620-Q1, AM625-Q1, AM625SIP Processor Family
          1. 7.4.3.1.1 PRU Subsystem
          2. 7.4.3.1.2 PRUSS Checklist
      4. 7.4.4 Universal Asynchronous Receiver/Transmitter (UART)
        1. 7.4.4.1 UART Interface When Not Used
        2. 7.4.4.2 Universal Asynchronous Receiver/Transmitter (UART) Checklist
      5. 7.4.5 Modular Controller Area Network (MCAN) with Full CAN-FD Support
        1. 7.4.5.1 Modular Controller Area Network Checklist
    5. 7.5 On-board Synchronous Communication Interface (MCSPI, MCASP and I2C)
      1. 7.5.1 Multichannel Serial Peripheral Interface (MCSPI) and Audio Peripheral - Multichannel Audio Serial Port (MCASP)
        1. 7.5.1.1 Connection of MCSPI and MCASP Interface Signals
        2. 7.5.1.2 MCSPI Interface Checklist
        3. 7.5.1.3 MCASP Interface Checklist
      2. 7.5.2 Inter-Integrated Circuit (I2C)
        1. 7.5.2.1 I2C Interface Signals Connection
        2. 7.5.2.2 I2C (Open-drain Output Type IO Buffer) Interface Checklist
        3. 7.5.2.3 I2C (Emulated Open-drain Output Type IO) Interface Checklist
    6. 7.6 User Interface (CSIRX0, DPI, OLDI0), GPIO and Hardware Diagnostics
      1. 7.6.1 Camera Serial Interface (CSI-RX, CSI-2, CSIRX0)
        1. 7.6.1.1 CSIRX0 Peripheral When Used
        2. 7.6.1.2 CSIRX0 Peripheral When Not Used
        3. 7.6.1.3 CSIRX0 Peripheral Checklist
      2. 7.6.2 Display Subsystem (DSS)
        1. 7.6.2.1 Display Parallel Interface (DPI)
          1. 7.6.2.1.1 AM625, AM623, AM625-Q1, AM625SIP Processor Family
            1. 7.6.2.1.1.1 IO Power Supply
            2. 7.6.2.1.1.2 Connection
            3. 7.6.2.1.1.3 DPI (Attached Device) Reset
            4. 7.6.2.1.1.4 DPI Signals Connection
            5. 7.6.2.1.1.5 Capacitors for the Power Supply Rails
            6. 7.6.2.1.1.6 DPI (VOUT0) Peripheral Checklist
          2. 7.6.2.1.2 AM620-Q1 Processor Family
        2. 7.6.2.2 Open LVDS Display Interface (OLDI0)
          1. 7.6.2.2.1 AM625, AM623, AM625-Q1, AM625SIP Processor Family
            1. 7.6.2.2.1.1 OLDI0 Display Interface Used
              1. 7.6.2.2.1.1.1 OLDI0 Interface Compatibility
              2. 7.6.2.2.1.1.2 IO Power Supply
              3. 7.6.2.2.1.1.3 OLDI0 (Attached Device) Reset
              4. 7.6.2.2.1.1.4 Capacitors for the Power Supply Rail
            2. 7.6.2.2.1.2 OLDI0 Peripheral Not Used
            3. 7.6.2.2.1.3 Additional Information
            4. 7.6.2.2.1.4 OLDI0 Peripheral Checklist
          2. 7.6.2.2.2 AM620-Q1 Processor Family
      3. 7.6.3 General Purpose Input/Output (GPIO)
        1. 7.6.3.1 Availability of CLKOUT on Processor GPIO
        2. 7.6.3.2 GPIO Connection and Addition of External Buffer
        3. 7.6.3.3 Additional Information
        4. 7.6.3.4 GPIO Checklist
      4. 7.6.4 On-board Hardware Diagnostics
        1. 7.6.4.1 Monitoring of On-board Supply Voltages Using Processor Voltage Monitors
          1. 7.6.4.1.1 Voltage Monitor Inputs Connection When Used
            1. 7.6.4.1.1.1 Voltage Monitor Checklist
          2. 7.6.4.1.2 Voltage Monitor Inputs Connection When Not Used
        2. 7.6.4.2 Internal Temperature Monitoring
          1. 7.6.4.2.1 Internal Temperature Monitoring Checklist
        3. 7.6.4.3 Connection of Error Signal Output (MCU_ERRORn)
        4. 7.6.4.4 High Frequency Oscillator (MCU_OSC0) Clock Loss Detection
          1. 7.6.4.4.1 Crystal or External Oscillator Mal-function
    7. 7.7 SK Specific Circuit Implementation (Reuse)
    8. 7.8 Performing Board Level Testing During Custom Board Bring-up
      1. 7.8.1 Processor Pin Configuration Using PinMux Tool
      2. 7.8.2 Schematics Configurations
      3. 7.8.3 Connection of Supply Rails to External Pullups
      4. 7.8.4 Peripheral (Subsystem) Clock Outputs
      5. 7.8.5 General Board Bring-up and Debug
        1. 7.8.5.1 Clock Output for Board Bring-Up, Test, or Debug
        2. 7.8.5.2 Additional Information
        3. 7.8.5.3 General Board Bring-up and Debug Checklist
  11. 8 Self-Review of Custom Board Schematic Design
  12. 9 Custom Board Layout Notes (Added Near to the Schematic Sections) and General Guidelines
    1. 9.1 Layout Considerations
  13. 10Custom Board Design Simulation
    1. 10.1 DDR-MARGIN-FW
  14. 11Additional References
    1. 11.1 FAQs Covering AM64x, AM243x, AM62x, AM62Ax, AM62D-Q1, AM62Px, AM62Lx Processor Families
    2. 11.2 FAQs - Processor Product Family Wise and Sitara Processor Families
    3. 11.3 Schematics Review (Self) and Schematic Review Request (Suppliers)
    4. 11.4 Processor Attached Devices Checklist
  15. 12User's Guide Content and Usage Summary
  16. 13References
    1. 13.1  AM625, AM623, AM620-Q1, AM625-Q1, AM625SIP
    2. 13.2  AM62L
    3. 13.3  AM62P, AM62P-Q1
    4. 13.4  AM62A7, AM62A3, AM62A7-Q1, AM62A3-Q1, AM62A1-Q1
    5. 13.5  AM62D-Q1
    6. 13.6  Common for all Processor Families
    7. 13.7  Master List of Available FAQs - Processor Family Wise
    8. 13.8  Master List of Available FAQs - Sitara Processor Families
    9. 13.9  FAQs Including Software Related
    10. 13.10 FAQs for Attached Devices
  17. 14Terminology
  18. 15Revision History
7.3.2.1.1.5 MMC0 (eMMC) Checklist

General

Review and verify the following for the custom schematic design:

  1. Reviewed above "Common checklist for all sections" section of the user's guide.
  2. MMC0 interface is compliant with the JEDEC eMMC electrical standard v5.1 (JESD84-B51) and implements a soft eMMC PHY.
  3. Connection of pulls for DAT0 and CMD signals.
  4. Series resistor provision for MMC0_CLK and placement.
  5. Pulldown implementation for MMC0_CLK and value.
  6. Processor IO supply for IO group (VDDSHV4) and the attached eMMC device IO supply power source.
  7. Implementation of attached device reset logic to support boot mode configuration.
  8. Implementation of attached device reset logic in case boot from the attached device is not required.
  9. Reset signal IO level compatibility between processor and attached device.
  10. Addition of required capacitors and value.

Schematic Review

Follow the below list for the custom schematic design:

  1. Required bulk and decoupling capacitors are provided for processor and attached device IO supply rails. The recommendation is to compare with the SK schematic (SK-AM62P-LP) implementation as a starting point.
  2. The recommendation is to compare the eMMC memory interface with SK schematic implementation for provisioning of parallel pulls, series resistors, and the resistor values.
  3. IO supply for IO group VDDSHV4 (1.8V or 3.3V) and the attached eMMC device IO supply is powered from the same power source and follow the ROC.
  4. The recommendation is to connect external pullup (47kΩ) for the MMC0_DAT0 and MMC0_CMD signals close to eMMC device. Provision for external pullups is optional for MMC0_DAT[7:1]. (The eMMC device (as long as the eMMC device is compliant to the eMMC JEDEC standard) has the pullups enabled for data signals MMC0_DAT[7:1]. The eMMC device turns off the MMC0_DAT[3:1] pullups when entering 4-bit mode and MMC0_DAT[7:1] pullups when entering 8-bit mode. The eMMC host software turns on the respective MMC0_DAT[7:1] pullups when the software changes the mode).
  5. The recommendation is to provision for a series resistor (0Ω) on MMC0_CLK and placed close to the processor clock output pin. The series resistor has been provisioned to control possible signal reflections, which can cause false clock transitions.
  6. The recommendation is to add a pulldown (10kΩ) to the eMMC attached device clock signal near to the attached device clock input (since there are cases where the clock is stopped or paused in a low logic state and the pulldown option is consistent with the logic state).
  7. In case eMMC boot mode configuration is required, 2-input ANDing logic can be used for implementing eMMC attached device reset. Processor GPIO is connected as one of the inputs to the AND gate with provision for pullup near to the ANDing logic AND gate input and provision for 0Ω to isolate the GPIO output for testing or debug. The other input to the AND gate is the MAIN domain warm reset status output (RESETSTATz).
  8. Alternatively, warm reset status output RESETSTATz can be connected directly to reset the attached device. In case RESETSTATz is used, the recommendation is to match IO level between the processor reset status output and the attached device reset input. The recommendation is to verify IO level matching implementation (level shifter or resistor) follow the design recommendations.
  9. In case eMMC memory is not used for boot, the attached eMMC device reset input can be controlled by using processor GPIO only. The recommendation is to pulldown the reset input of the eMMC memory device.

Additional

  1. ANDing logic additionally performs IO level translation. The recommendation is to verify the reset input IO level compatibility while optimizing the reset ANDing logic. IO level mismatch can cause supply leakage and affect board performance.
  2. An external pullup on CMD and DAT0 is recommended as per the eMMC JEDEC standard and also to make sure the attached eMMC memory device inputs does not float until the software initializes the processor IOs associated with MMC0 interface. External pulls are recommended because the IOs associated with MMC0 are implemented with standard dual-voltage LVCMOS IO cells with the capability of multiplexing additional signal functions to the respective device pins. MMC0 IOs buffers are disabled during reset.
  3. The recommendation is to verify eMMC memory device reset eMMC_RSTn is enabled (eMMC non-volatile configuration space) for the external reset logic to be functional. The GPIO reset option is used to reset the attached eMMC device without resetting entire processor if there is a case where the peripheral becomes unresponsive. Only warm reset status output can be used to reset the attached eMMC device. Software forces a warm reset when the peripheral becomes unresponsive. However, using warm reset status output resets the entire processor, rather than trying to recover the specific peripheral without resetting the entire processor. When RESETSTATz is used to reset the attached device, the recommendation is to verify the IO level of RESETSTATz matches the attached device IO levels.
  4. A level translator is recommended to match the reset IO level. A resistor divider can be used alternatively for level shifting, provided optimum value of the resistor divider is selected. If this is too high, then the rise or fall time of the eMMC reset input can be slow and introduce too much delay. If this is too low, then the processor sources too much steady-state current during normal operation.
  5. Adding a capacitor at the reset input of eMMC attached device is not recommended when RESETSTATz or processor IO is connected directly. A stand-alone reset connection using RC to reset the eMMC memory device is not recommended.