Intel PXA255 Personal Computer User Manual


 
15-28 Intel® PXA255 Processor Developer’s Manual
MultiMediaCard Controller
15.5.7 MMC_RDTO Register (MMC_RDTO)
MMC_RDTO, shown in Table 15-11, determines the length of time that the controller waits after a
command before it turns on the time-out error if data has not been received. The length of time
before a time-out occurs is measured in increments of 256 20 MHz periods and can be calculated as
follows:
It is the software’s responsibility to calculate the value for READ_TO. The default value is 0xffff,
which corresponds to 838.848 ms.
This is a read/write register. Ignore reads from reserved bits. Write zeros to reserved bits.
Time-out Delay
MMC_RDTO[READ_TO]()256()×
20MHz
------------ ---------------------------------- --------------------------------------------
MMC_RDTO[READ_TO]()128()×
10
7
------------- ---------------------------------- -------------------------------------------
sec==
Table 15-11. MMC_RDTO Register
Physical Address
0x4110_0018
MMC_RDTO Register MultiMediaCard Controller
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
reserved READ_TO
Reset
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Bits Name Description
31:16 reserved
15:0 READ_TO Specifies the length of time before a data read time-out