User manual

MCP42XXEV Evaluation Board User’s Guide
DS51898A-page 18  2010 Microchip Technology Inc.
2.4.2 The MCP4261 Device
To make variations to the commands sent to the MCP4261 device (from the commands
shown in the demo section), one must know the device memory map (see Table 2-3)
and the command formats (see Figure 2-3). For additional device operational
information, refer to the MCP4261 device data sheet (DS22059).
TABLE 2-3: MEMORY MAP AND THE SUPPORTED COMMANDS
FIGURE 2-3: MCP42XX SPI Command Formats.
Address Function
Memory
Type
Allowed Commands
Disallowed
Commands
(2)
00h Volatile Wiper 0 RAM Read, Write,
Increment, Decrement
—
01h Volatile Wiper 1 RAM Read, Write,
Increment, Decrement
—
02h Nonvolatile Wiper 0 EEPROM Read, Write
(1)
Increment, Decrement
03h Nonvolatile Wiper 1 EEPROM Read, Write
(1)
Increment, Decrement
04h Volatile
TCON0 Register
RAM Read, Write Increment, Decrement
05h STATUS Register RAM Read Write, Increment,
Decrement
06h-0Fh Data EEPROM EEPROM Read, Write
(1)
Increment, Decrement
Note 1: When an EEPROM write is active, these are invalid commands and will generate
an error condition. The user should use a read of the STATUS register to determine
when the write cycle has completed. To exit the error condition, the user must take
the CS
pin to the V
IH
level and then back to the active state (V
IL
or V
IHH
).
2: This command on this address will generate an error condition. To exit the error
condition, the user must take the CS
pin to the V
IH
level and then back to the active
state (V
IL
or V
IHH
).
A
D
3
A
D
2
A
D
1
A
D
0
C
1
C
0
D
9
D
8
Register Memory
Command Byte
Data
Address
Bits
Command
Bits
A
D
3
A
D
2
A
D
1
A
D
0
C
1
C
0
D
9
D
8
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
Register Memory
16-bit Command
Data
Address
Bits
Command
Bits
0 0 = Write Data
0 1 = INCR
1 0 = DECR
1 1 = Read Data
C C
1 0
Command
Bits
8-bit Command
Command Byte
Data Byte
(Increment or Decrement)
(Read Data or Write Data)