MMC/SD Host Controller
7-143
MPU Public Peripherals
The 16-bit MMC command time-out register (MMC_CTO) specifies the
maximum number of clock cycles before a command time-out condition
occurs.
Table 7–103. MMC Command Time-out Register (MMC_CTO)
Bit
Name
Description
15 –8
Reserved
7–0
CTO
MMC command time-out value.
Command Time-out Value (CTO)
MMC/SD mode only.
The local host sets this field (bits 7:0) based on N
CR
clock cycles. MMC and
SD card specifies N
CR
to be between 2 and 64 clock cycles.
If the card does not respond within the specified number of cycles, command
time-out gets set to 1 in MMC_STAT[7] register bit.
For MMC card interrupt mode support, this time-out is disabled when the
command passes with an R5 response (CMD40).
-
0x00: Command time-out disabled
-
0x01: One clock cycle
-
0xFD: 253 clocks cycles (2
8
– 3)
The 0xFF and 0xFE cannot be used.
Values after reset are low (all 8 bits).