EarthLCD ezLCD-405, Руководство пользователя

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© 2016 Earth Computers Tech. Inc.
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.
ezLCD Response
After receiving the SD_FILE_READ command, the ezLCD responds with either of the following
sequences:
In case of the success :
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+1: Data Byte n
Note: If the Number of Bytes to Read is greater than the number of bytes left in the file, all of
the extra bytes will be preempted by 0.
In case of an error :
7 6 5 4 3 2 1 0
0 0 1 1 1 1 1 0 Byte 0: 3E hex, 62 dec
The ezLCD response is sent through the same interface, which received the SD_FILE_READ
command.
Example:
The following flow chart shows an example of reading first 16 bytes from the file MyFile.dat
SD_FILE_LIST
Data Byte 0
Data Byte n
Data Byte 0
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