SD Change Bus Width

Zynq UltraScale+ Device Technical Reference Manual (UG1085)

Document ID
UG1085
Release Date
2022-09-15
Revision
2.3 English
Table 26-25:      SD Change Bus Width

Task

SD{0, 1}
Registers

Register Field

Register Offset

Bits

Value

For SD Card

Send block write command (CMD55) (see Table: SD CMD Transfer) if not defined as eMMC card.

Send CMD6 command with 4-bit data bus width selected.

Set bus width in host control register.

reg_hostcontrol1

hostctrl1_datawidth

0x28

1

1b'1

Read card specific data in response.

reg_response0

command_response

0x10

15:0

Read

For eMMC

Send ACMD6 command with 4-bit data bus width selected.

Wait for 2 ms.

Set bus width in host control register.

reg_hostcontrol1

hostctrl1_datawidth

0x28

1

1b'1

Read card specific data in response.

reg_response0

command_response

0x10

15:0

Read