GD32W51x User Manual
763
Then receive response from the card if CMDRESP in SDIO_CMDCTL register is not
0b00/0b10. There are short response which have 48 bits or long response which have 136
bits. The response stores in SDIO_RESP0 - SDIO_RESP3 registers. The command unit also
generates the command status flags defined in SDIO_STAT register.
Command state machine
CS_Idle
After reset, ready to send command.
1.CSM enabled and WAITDEND enabled
→
CS_Pend
2.CSM enabled and WAITDEND disabled
→
CS_Send
3.CSM disabled
→
CS_Idle
Note:
The state machine remains in the Idle state for at least eight SDIO_CK periods to meet
the N
CC
and N
RC
timing constraints. N
CC
is the minimum delay betw een tw o host commands ,
and N
RC
is the minimum delay betw een the host command and the response.
CS_Pend
Waits for the end of data transfer.
1.The data transfer complete
→
CS_Send
2.CSM disabled
→
CS_Idle
CS_Send
Sending the command.
1.The command transmitted has response
→
CS_Wait
2.The command transmitted doesn’t have response →
CS_Idle
3.CSM disabled
→
CS_Idle
CS_Wait
Wait for the start bit of the response.
1.Receive the response(detected the start bit)
→
CS_Receive
2.Timeout is reached w ithout receiving the response
→
CS_Idle
3.CSM disabled
→
CS_Idle
Note:
The command timeout has a fixed value of 64 SDIO_CK clock periods.
CS_Receive
Receive the response and check the CRC.
1.Response Received in CE-ATA mode and
interrupt disabled and w ait for CE-ATA Command
Completion signal enabled
→
CS_Waitcompl
2.Response Received in CE-ATA mode and
interrupt disabled and w ait for CE-ATA Command
Completion signal disabled
→
CS_Pend
3.CSM disabled
→
CS_Idle
4.Response received
→
CS_Idle
5.Command CRC failed
→
CS_Idle