MCP4641-502ESLASHMS datasheet(58/92 Pages) MICROCHIP

58 / 92 page

MCP454X/456X/464X/466X

DS22107A-page 58

7.4

Write Data

Normal and High Voltage

The Write Command can be issued to both the Volatile

and Non-Volatile memory locations. The format of the

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

Byte, an A bit, the MCP4XXX Command Byte, an A bit,

the MCP4XXX Data Byte, an A bit, and a Stop (or

Restart) condition. The MCP4XXX 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 Non-Volatile 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

MCP4XXX after every byte transfer (during the

Acknowledge). If a Stop or Restart condition is gener-

ated during a data transfer (before the A), the data will

not be written to the MCP4XXX. 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 NON-VOLATILE

MEMORY

The sequence to write to a single non-volatile 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 volatile

memory (addresses 00h, 01h, 04h, and 05h) is allowed

when using the appropriate command sequence.

Commands that address non-volatile 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

Cycle.

Once a write command to a Non-Volatile memory

location has been received, No other commands

should be received before the Stop condition occurs.

Figure 7-2 show 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, and 04h). 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

NON-VOLATILE MEMORY

If a continuous write is attempted on Non-Volatile

memory, the missing Stop condition will cause the com-

mand 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

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

MCP45XX/46XXs 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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