EarthLCD ezLCD-405, Руководство пользователя

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Rev.
© 2016 Earth Computers Tech. Inc.
1.7.41 SD_FILE_TELL
Description: Gets the File Position Index of the opened SD Flash file.
Supported file systems : FAT12, FAT16, FAT32
Code: 7B hex, 123 dec
7 6 5 4 3 2 1 0
Byte 0: Command
Byte 1: File ID
Notes: SD card has to be formatted in the supported file system.
This command works only if the file is already opened by the SD_FILE_OPEN
command, or created and opened by the SD_FILE_CREATE command.
See Also: SD_FILE_OPEN , SD_FILE_SEEK , SD_FILE_CLOSE , SD_FILE_CLOSE_ALL
About the File ID:
File ID is returned in the response to the SD_FILE_OPEN command. It 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 Position Index
The File Position Index specifies the Read/Write position offset (in bytes) from the beginning of
the file. Upon opening of the file, the File Position Index is set to 0. The File Position Index is
incremented by the subsequent read or write operations on the opened file.
ezLCD Response
After receiving the SD_FILE_TELL command, the ezLCD responds with either of the following
sequences:
SD_FILE_TELL
FILE ID