MCP4441 datasheet(64/100 Pages) MICROCHIP

64 / 100 page

MCP444X/446X

DS22265A-page 64

7.4

Write Data

Normal and High Voltage

The Write Command can be issued to both the Volatile

and Nonvolatile memory locations. The format of the

command, see Figure 7-2, includes the I2C Control

Byte, an A bit, the MCP44XX Command Byte, an A bit,

the MCP44XX Data Byte, an A bit, and a Stop (or

Restart) condition. The MCP44XX generates the A / A

bits.

A Write command to a Volatile memory location

changes that location after a properly formatted Write

Command and the A / A clock have been received.

A Write command to a Nonvolatile memory location will

only start a write cycle after a properly formatted Write

Command have been received and the Stop condition

has occurred.

7.4.1

SINGLE WRITE TO VOLATILE

MEMORY

For volatile memory locations, data is written to the

MCP44XX after every byte transfer (during the

Acknowledge). If a Stop or Restart condition is

generated during a data transfer (before the A), the

data will not be written to the MCP44XX. After the A bit,

the master can initiate the next sequence with a Stop or

Restart condition.

Refer to Figure 7-2 for the byte write sequence.

7.4.2

SINGLE WRITE TO NONVOLATILE

MEMORY

The sequence to write to a single nonvolatile memory

location is the same as a single write to volatile memory

with the exception that the EEPROM write cycle (twc) is

started after a properly formatted command, including

the Stop bit, is received. After the Stop condition

occurs, the serial interface may immediately be

re-enabled by initiating a Start condition.

During an EEPROM write cycle, access to the volatile

memory (addresses 00h, 01h, 04h, 05h, 06h, 07h, and

0Ah) is allowed when using the appropriate command

sequence. Commands that address nonvolatile

memory are ignored until the EEPROM write cycle (twc)

completes. This allows the Host Controller to operate

on the Volatile Wiper registers, the TCON register, and

to Read the Status Register. The EEWA bit in the

Status register indicates the status of an EEPROM

Write Cycle.

Once a write command to a Nonvolatile memory

location has been received, no other commands should

be received before the Stop condition occurs.

Figure 7-2 shows the waveform for a single write.

7.4.3

CONTINUOUS WRITES TO

VOLATILE MEMORY

A continuous write mode of operation is possible when

writing to the volatile memory registers (address 00h,

01h, 04h, 06h, 07h, and 0Ah). This continuous write

mode allows writes without a Stop or Restart condition

or repeated transmissions of the I2C Control Byte.

Figure 7-3 shows the sequence for three continuous

writes. The writes do not need to be to the same volatile

memory address. The sequence ends with the master

sending a STOP or RESTART condition.

7.4.4

CONTINUOUS WRITES TO

NONVOLATILE MEMORY

If a continuous write is attempted on Nonvolatile

memory, the missing Stop condition will cause the

command to be an error condition (A). A Start bit is

required to reset the command state machine.

7.4.5

THE HIGH VOLTAGE COMMAND

(HVC) SIGNAL

The High Voltage Command (HVC) signal is

multiplexed with Address 0 (A0) and is used to indicate

that the command, or sequence of commands, are in

the High Voltage operational state. High Voltage

commands allow the device’s WiperLock Technology

and write protect features to be enabled and disabled.

The HVC pin has an internal resistor connection to the

MCP44XXs internal VDD signal.

Note:

Writes to certain memory locations will be

dependant on the state of the WiperLock

Technology bits and the Write Protect bit.

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