e z L C D -‐ 4 0 5
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105
Rev.
© 2016 Earth Computers Tech. Inc.
1.7.37 SD_FILE_OPEN
Description:
Opens an
existing
SD Flash file for reading or writing. File Position Index is set to
0. In order to open non-‐existing, new file, use the command
SD_FILE_CREATE
Supported file systems
: FAT12, FAT16, FAT32
Code:
71
hex,
113
dec
7
6
5
4
3
2
1
0
Byte 0: Command
Byte 2: First Character of the file path
Byte 3: Second Character of the file path
Byte n: Last Character
Byte n+1: NULL
Notes:
SD card has to be formatted in the supported file system.
See Also:
SD_FILE_CREATE
,
SD_FILE_CLOSE
,
SD_FILE_CLOSE_ALL
About the File ID:
File ID identifies the file after it has been opened. Since maximum 2 files may be concurrently
opened, the File ID should be: 1 or 2. Values higher than 2 are interpreted as 2 and 0 is
interpreted as 1.
About the File Path:
·∙ File Path specifies the full path to the file on SD including directory, filename and extension
·∙ Directories should be separated by: / (
not by: \
like in Windows and DOS).
·∙ File Path is not case-‐sensitive. The drive and root directory do not have to be indicated, for
example, both: A:/Cat/Jumped/Over.txt and cat/jumped/over.TXT specify the same file.
·∙ Long file names are supported, however the File Path (directory + filename + extension +
NULL) may not exceed 64 bytes.
SD_FILE_LIST
ASCII
ASCII
0
ASCII
Pat
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to
th
e
fil
e
on
S
D
(N
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LL
-‐te
rm
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