Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 11/11/2022
Public

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16.4.3.1.2. Send Command and Receive Response

After a new command is loaded in the command path (the update_clock_registers_only bit in the cmd register is set to 0), the command path state machine sends out a command on the card bus.
Figure 46.  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 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.