Altera Cyclone V Device Handbook page 694

11-16
Send Response to BIU
Figure 11-6: Command Path State Machine
The command path state machine performs the following functions, according to cmd register bit values:
1. send_initialization Initialization sequence of 80 clock cycles is sent before sending the
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command.
2. response_expected A response is expected for the command. After the command is sent out, the
command path state machine receives a 48-bit or 136-bit response and sends it to the BIU. If the start
bit of the card response is not received within the number of clock cycles (as set up in the tmout register),
the rto bit and command done (CD) bit are set to 1 in the rintsts register, to signal to the BIU. If the
response-expected bit is set to 0, the command path sends out a command and signals a response done
to the BIU, which causes the cmd bit to be set to 1 in the rintsts register.
3. response_length If this bit is set to 1, a 136-bit long response is received; if it is set to 0, a 48-bit
short response is received.
4. check_response_crc If this bit is set to 1, the command path compares CRC-7 received in the
response with the internally-generated CRC-7. If the two do not match, the response CRC error is signaled
to the BIU, that is, the rcrc bit is set to 1 in the rintsts register.
Send Response to BIU
If the response_expected bit is set to 1 in the cmd register, the received response is sent to the BIU.
Response register 0 (resp0) is updated for a short response, and the response register 3 (resp3), response
register 2 (resp2), response register 1 (resp1), and resp0 registers are updated on a long response, after
which the cmd bit is set to 1 in the rintsts register. If the response is for an AUTO_STOP command sent
by the CIU, the response is written to the resp1 register, after which the auto command done bit (acd) is
set to 1 in the rintsts register.
The command path verifies the contents of the card response.
Table 11-9: Card Response Fields
Response transmission bit
Command index
End bit
Altera Corporation
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load_new_cmd
response_expected = 0
Transmit
Command
response_expected = 1
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Field
t Done
Command
NCC
Idle
wait_tncc
Send IRQ
Response
Request
Response Done/
Receive
Response Timeout
Response
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0
Command index of the sent command
1
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2013.12.30
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