6.10.12 MMC/SD
The multimedia card (MMC), secure digital (SD), and secure digital I/O (SDIO) high-speed controller (MMC/SD) provides an interface between a local host (LH) such as microprocessor unit (MPU) or digital signal processor (DSP) and either MMC, SD memory card, or SDIO card and handles MMC, SD, and SDIO transactions with minimal LH intervention. There are two MMC/SD host controllers inside the device. Each controller has an 8-bit wide data bus.
The MMC/SD host controllers support the following main features:
- Full compliance with MMC/eMMC command/response sets as defined in the JC64 MMC/eMMC Standard Specification, v4.5.
- Full compliance with SD command/response sets as defined in the SD Physical Layer Specification v3.01.
- Full compliance with SDIO command/response sets and interrupt/read-wait suspend-resume operations as defined in the SD part E1 Specification v3.00.
- Full compliance with SD Host Controller Standard Specification sets as defined in the SD card Specification Part A2 v3.00.
Main features of the MMC/SD host controllers:
- Flexible architecture allowing support for new command structure
- Designed for low power (Local Power Management)
- Programmable clock generation
- Card insertion/removal detection and write protect detection
- The slave interface supports:
- 32-bit wide data bus
- Streaming burst supported only with burst length up to 7
- WNP supported
- The master interface supports:
- 32-bit wide data bus
- Burst supported
- Built-in 1024-byte buffer for read or write
- Two DMA channels, one interrupt line
- Support JC 64 v4.4.1 boot mode operations
- Support SDA 3.00 Part A2 programming model
- Support SDA 3.00 Part A2 DMA feature (ADMA2)
- Supported data transfer rates:
- MMC0 supports the following data transfer rates (eMMC/SD):
- SDR12 (3.3 V IOs): up to 12 MBps (24 MHz clock)
- SDR25 (3.3 V IOs): up to 24 MBps (48 MHz clock)
- HS mode (3.3 V IOs): up to 24 MBps (48 MHz clock)
- DS mode (3.3 V IOs): up to 12 MBps (24 MHz clock)
- Default SD mode 1-bit data transfer up to 24 Mbps (3 MBps)
- MMC1 supports the following data transfer rates (eMMC):
- SDR12 (1.8 V IOs): up to 12 MBps (24 MHz clock)
- SDR25 (1.8 V IOs): up to 24 MBps (48 MHz clock)
- DDR50 (1.8 V IOs): up to 48 MBps (48 MHz clock)
- 1.8 V legacy modes with 1/4/8-bit single data rate at up to 26 MHz bus clock
- MMC0 Supports 3.3-V IO modes only
- MMC1 Supports 1.8-V IO modes only
The differences between the MMC/SD host controller and a standard SD host controller defined by the SD Card Specification, Part A2, SD Host Controller Standard Specification, v3.00 are:
- The clock divider in the MMC/SD host controller supports a wider range of frequency than specified in the SD Memory Card Specifications, v3.0. The MMC/SD host controller supports odd and even clock ratio.
- The MMC/SD host controller supports configurable busy time-out.
- ADMA2 64-bit mode is not supported.
- There is no external LED control.
The following features are not supported:
- Byte or half-word accesses. Only word accesses to the slave port are supported.
- MMC Out-of-band interrupt.
- Dual voltage I/O (MMC0 Supports 3.3-V only. MMC1 Supports 1.8-V only).
- No built-in hardware support for error correction codes (ECC).
- SPI transfers are not supported.
- Module doesn’t support card insertion/removal sensing with pull up resistor on MMCi_DAT[3] data bus line as specified in the SD Physical Layer Specification.
For more information, see section Multimedia Card High Speed Interface (MMC/SD) in chapter Peripherals of the Device TRM.