DocID018909 Rev 11 1051/1731
RM0090 Secure digital input/output interface (SDIO)
1067
31.7 CE-ATA specific operations
The following features are CE-ATA specific operations:
• sending the command completion signal disable to the CE-ATA device
• receiving the command completion signal from the CE-ATA device
• signaling the completion of the CE-ATA command to the CPU, using the status bit
and/or interrupt.
The SDIO supports these operations only for the CE-ATA CMD61 command, that is, if
SDIO_CMD[14] is set.
31.7.1 Command completion signal disable
Command completion signal disable is sent 8 bit cycles after the reception of a short
response if the ‘
enable CMD completion’ bit, SDIO_CMD[12], is not set and the ‘not interrupt
Enable’ bit,
SDIO_CMD[13], is set.
The CPSM enters the Pend state, loading the command shift register with the disable
sequence “00001” and, the command counter with 43. Eight cycles after, a trigger moves
the CPSM to the Send state. When the command counter reaches 48, the CPSM becomes
Idle as no response is awaited.
31.7.2 Command completion signal enable
If the ‘enable CMD completion’ bit SDIO_CMD[12] is set and the ‘not interrupt Enable’ bit
SDIO_CMD[13] is set, the CPSM waits for the command completion signal in the Waitcpl
state.
When ‘0’ is received on the CMD line, the CPSM enters the Idle state. No new command
can be sent for 7 bit cycles. Then, for the last 5 cycles (out of the 7) the CMD line is driven to
‘1’ in push-pull mode.
31.7.3 CE-ATA interrupt
The command completion is signaled to the CPU by the status bit SDIO_STA[23]. This static
bit can be cleared with the clear bit SDIO_ICR[23].
The SDIO_STA[23] status bit can generate an interrupt on each interrupt line, depending on
the mask bit SDIO_MASKx[23].
31.7.4 Aborting CMD61
If the command completion disable signal has not been sent and CMD61 needs to be
aborted, the command state machine must be disabled. It then becomes Idle, and the
CMD12 command can be sent. No command completion disable signal is sent during the
operation.
To Next Page
Loading...
Need help?
General
