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MMC/SD/SDIO Use Cases and Tips
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24.6.1.3.2.4 Sending CMD1
Once the card response is available in register MMCHS1.
, the software is responsible to
compare Card OCR and Host OCR, and then send a second CMD1 command with the cross-checked
OCR.
This way, the card is notified of the Operating Voltage to work with.
Table 24-18. Sending CMD1
Register Name
Register Address
Value
Value Description
MMCHS1.
0x4809C02C
0x00000001
MMC bus is still in open drain state for broadcast.
MMCHS1.
0x4809C134
0x00050001
Enables CC, CTO and CEB events to occur.
MMCHS1.
0x4809C138
0x00050001
Enables CC, CTO and CEB interrupts to rise.
MMCHS1.
0x4809C10C
0x01020000
Sends CMD1 whose opcode is 1 and response
type is 48 bits.
Once the card response is available in register MMCHS1.
, the software should compare
card OCR and host OCR, and then send a second CMD1 command with the cross-checked OCR. This
tells the card what operating voltage to use.
24.6.1.3.2.5 Sending CMD2
This command asks the MMC card to send its CID register's content (see
). The response is
128 bit wide and is received in MMCHS1.
, MMCHS1.
,
and MMCHS1.
registers.
Table 24-19. Sending CMD2
Register Name
Register Address
Value
Value Description
MMCHS1.
0x4809C02C
0x00000001
MMC bus is still in open drain state for broadcast.
MMCHS1.
0x4809C134
0x00070001
Enables CERR, CIE, CCRC, CC, CTO and CEB
events to occur.
MMCHS1.
0x4809C138
0x00070001
Enables CERR, CIE, CCRC, CC, CTO and CEB
interrupts to rise.
MMCHS1.
0x4809C10C
0x02090000
Sends CMD2 whose opcode is 2, response type is
136 bits with CCCE enabled.
24.6.1.3.2.6 Sending CMD3
This command sets MMC card address (see
). Useful when MMCHS controller switches to
addressed mode.
Table 24-20. Sending CMD3
Register Name
Register Address
Value
Value Description
MMCHS1.
0x4809C02C
0x00000001
MMC bus is still in open drain state for broadcast.
MMCHS1.
0x4809C134
0x100f0001
Enables CERR, CIE, CCRC, CC, CTO and CEB
events to occur.
MMCHS1.
0x4809C138
0x100f0001
Enables CERR, CIE, CCRC, CC, CTO and CEB
interrupts to rise.
MMCHS1.
0x4809C10C
0x031a0000
Sends CMD3 whose opcode is 3, response type is
48 bits with CICE and CCCE enabled.
MMCHS1.
0x4809C108
0x00010000
register carries MMC card's
address. We choose to assign address 1 any other
16 bit wide value is valid.
3418
MMC/SD/SDIO Card Interface
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated