Datasheet

 2008-2013 Microchip Technology Inc. DS22107B-page 57
MCP454X/456X/464X/466X
7.2 Data Byte
Only the Read Command and the Write Command
have Data Byte(s).
The Write command concatenates the 8-bits of the
Data Byte with the one data bit (D8) contained in the
Command Byte to form 9-bits of data (D8:D0). The
Command Byte format supports up to 9-bits of data so
that the 8-bit resistor network can be set to Full-Scale
(100h or greater). This allows wiper connections to
Terminal A and to Terminal B. The D9 bit is currently
unused.
7.3 Error Condition
If the four address bits received (AD3:AD0) and the two
command bits received (C1:C0) are a valid combina-
tion, the MCP4XXX will Acknowledge the I
2
C bus.
If the address bits and command bits are an invalid
combination, then the MCP4XXX will Not Acknowledge
the I
2
C bus.
Once an error condition has occurred, any following
commands are ignored until the I
2
C bus is reset with a
Start Condition.
7.3.1 ABORTING A TRANSMISSION
A Restart or Stop condition in the expected data bit
position will abort the current command sequence and
data will not be written to the MCP4XXX.
TABLE 7-3: COMMANDS
Command Name
Writes
Value in
EEPROM
Operates on
Volatile/
Nonvolatile
memory
High
Voltage
(V
IHH
) on
HVC pin?
Impact on
WiperLock or
Write Protect
Works
when
Wiper is
“locked”?
Write Data Yes
(1)
Both — unlocked
(1)
No
Read Data — Both — unlocked
(1)
No
Increment Wiper — Volatile Only — unlocked
(1)
No
Decrement Wiper — Volatile Only — unlocked
(1)
No
High Voltage Write Data Yes Both Yes unchanged No
High Voltage Read Data — Both Yes unchanged Yes
High Voltage Increment Wiper — Volatile Only Yes unchanged No
High Voltage Decrement Wiper — Volatile Only Yes unchanged No
Modify Write Protect or WiperLock
Technology (High Voltage) - Enable
—
(2)
Nonvolatile Only
(2)
Yes locked/
protected
(2)
Yes
Modify Write Protect or WiperLock
Technology (High Voltage) - Disable
—
(3)
Nonvolatile Only
(3)
Yes unlocked/
unprotected
(3)
Yes
Note 1: This command will only complete, if wiper is “unlocked” (WiperLock Technology is Disabled).
2: If the command is executed using address 02h or 03h, that corresponding wiper is locked or
if with address 0Fh, then Write Protect is enabled.
3: If the command is executed using with address 02h or 03h, that corresponding wiper is unlocked or
if with address 0Fh, then Write Protect is disabled.