SD card
No card connected
MMC card
No
No
Send CMD55
Send ACM41
Time-out waiting
for answer?
Time-out waiting
for answer?
Yes
Yes
Send CMD1 command
init-026
SD/MMC booting
Public Version
Device Initialization by ROM Code
www.ti.com
if a card is plugged in. If no card is present, the ROM code goes to the next booting device. The standard
identification process and relative card address (RCA) assignment are used. However, the ROM code
searches for only one card connected on the bus. This is done using the CMD line common to the SD and
MMC cards. The MMC and SD standards describe this phase as the initialization phase. They differ in the
first commands, CMD1 and ACMD41. The ROM code uses this command difference to differentiate
between MMC and SD cards; that is, CMD1 is supported only by MMC, and ACMD41 is supported only by
SD. The ROM code first sends a CMD1 to the card and gets an answer only if an MMC card is connected.
If no answer is received, ACMD41 (a combination of CMD55 and ACMD41) is sent, and an answer is
expected from an SD card. If an answer is not received, no cards are connected and the ROM code exits
MMC/SD booting with FAIL.
shows the MMC/SD detection procedure.
Figure 26-28. MMC/SD Detection Procedure
26.4.7.6.3 Read Sector Procedure
•
Raw mode:
In raw mode, an image can be at offset 0 or 128KB and must not be bigger than 128KB. Raw mode is
3562
Initialization
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated
Содержание OMAP36 Series
Страница 174: ...174 List of Tables SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 692: ...692 MPU Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 1084: ...1084 IVA2 2 Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 1990: ...1990 2D 3D Graphics Accelerator SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2334: ...2334 Memory Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2700: ...2700 Memory Management Units SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2868: ...2868 HDQ 1 Wire SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2974: ...2974 UART IrDA CIR SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3054: ...3054 Multichannel SPI SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3462: ...3462 MMC SD SDIO Card Interface SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3508: ...3508 General Purpose Interface SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3584: ...3584 Initialization SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3648: ...3648 Debug and Emulation SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...