Altera Cyclone V Device Handbook page 714

11-36
cmd Register Settings for Non-Data Transfer Command
When a response is received either erroneous or valid the controller sets the command_done bit in the
rintsts register to 1. A short response is copied to resp0, while a long response is copied to all four
response registers (resp0, resp1, resp2, and resp3).
the MSB and bit 0 of resp0 represents the LSB.
For basic and non-data transfer commands, perform the following steps:
1. Write the cmdarg register with the appropriate command argument parameter.
2. Write the cmd register with the settings in Register Settings for Non-Data Transfer Command.
3. Wait for the controller to accept the command. The start_cmd bit changes to 0 when the command
is accepted.
The following actions occur when the command is loaded into the controller:
• If no previous command is being processed, the controller accepts the command for execution and
resets the start_cmd bit in the cmd register to 0. If a previous command is being processed, the
controller loads the new command in the command buffer.
• If the controller is unable to load the new command that is, a command is already in progress, a
second command is in the buffer, and a third command is attempted the controller generates a
hardware lock error.
4. Check if there is a hardware lock error.
5. Wait for command execution to complete. After receiving either a response from a card or response
timeout, the controller sets the command_done bit in the rintsts register to 1. Software can either
poll for this bit or respond to a generated interrupt (if enabled).
6. Check if the response timeout boot acknowledge received (bar), rcrc, or re bit is set to 1. Software
can either respond to an interrupt raised by these errors or poll the re, rcrc, and bar bits of the
rintsts register. If no response error is received, the response is valid. If required, software can copy
the response from the response registers.
Note: Software cannot modify clock parameters while a command is being executed.
Related Information
cmd Register Settings for Non-Data Transfer Command
Refer to this table for information about Non-Data Transfer commands.
cmd Register Settings for Non-Data Transfer Command
Table 11-16: cmd Register Settings for Non-Data Transfer Command
Parameter
start_cmd
use_hold_reg
update_clk_regs_only
data_expected
Altera Corporation
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1
1 or 0
0
0
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For long responses, bit 31 of resp3 represents
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on page 11-36
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Value
Default
This bit resets itself to 0 after the command is
committed.
Choose the value based on the speed mode being
used.
Indicates that the command is not a clock update
command
Indicates that the command is not a data command
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Comment
SD/MMC Controller
cv_54011
2013.12.30
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