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© Andigilog, Inc. 2006
www.andigilog.com
October 2006 - 70A05011
aSC7521A
8
8
8
8
8
Target Address
Write Length
Read Length
Command
FCS
0x48
0x01
0x00
0xE2
0xE0
Figure 11. Vendor Command Enable
VenCmdDisable()
Vendor Command Disable disables the Vendor Specified Extensions.
Write Data Length:
0x01
Read Data Length:
0x00
Command Code:
0xE3
8
8
8
8
8
Target Address
Write Length
Read Length
Command
FCS
0x48
0x01
0x00
0xE3
0xE7
Figure 12. Vendor Command Disable
Reserved or Unsupported Commands
Attempts to access the sensor using a reserved or unsupported command will not result in the device or bus failure. The sensor will
return a modified FCS when any of the following commands are received. To modify the FCS the sensor will invert all of the bits in
the correct FCS (1’s complement). A modified FCS is also called an Abort FCS.
The sensor will return an Abort FCS (modified FCS) for a reserved and unsupported command code (commands codes between
0xE4 to 0xF5 and 0xF8 to 0xFF).
The sensor will return an Abort FCS (modified FCS) for reserved commands (command codes 0x02 to 0xDF.
The sensor will return an Abort FCS (modified FCS) for unused vendor specific test and manufacturing command codes (command
codes 0xE8 to 0xEF). If any of these types of commands exist, they will be disabled during normal operation.
Malformed Commands
A malformed command is one which is valid but has an incorrect write or read length for the given command.
If a get temperature command with a write length not equal to 1 is sent, then the aSC7521A will send an Abort FCS and wait for a
new command. An Abort FCS will be formed by creating a 1’s complement of the the good FCS.
If a get temperature command and the read length is not equal to 2 or 4 then te aSC7521A will send an Abort FCS and wait for a
stop on the SST bus. See the Command Summary section for the expected Write and Read lengths of the legal commands.
There will be no checking for malformed WriteReg() and ReadReg() commands (Vendor Specific Extensions).
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