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I2C COMMUNICATION BETWEEN ST7 AND M24Cxx EEPROM

The communication protocol between the ST7 and the external M24Cxx EEPROM is given in

Figure 2. For more details, please refer to the ST24C08 datasheet.

The ST7 / M24Cxx communication application is based on two steps:

– Write the content of an output buffer (from the ST7 ROM) in the M24Cxx EEPROM

– Read this written buffer from the M24Cxx EEPROM to the ST7 RAM.

Figure 3. shows the flowchart of these two steps.

Figure 3. Communication Application Flowchart

ACK

START EEPROM @

SUB @

ACK

DATA 1

ACK

DATA 2

ACK

DATA N-1

DATA N

STOP

ACK

START EEPROM @

SUB @

ACK

DATA 1

ACK

DATA N

NACK STOP

ACK

START EEPROM @

ACK

Write data from ST7 to EEPROM

Read data from EEPROM to ST7

SEND SUB @ DATA

INITIATE TRANSMISSION

(START + SLAVE @)

END OF

BUFFER

yes

no

SEND NEXT BUFFER DATA

SEND SUB @ DATA

INITIATE TRANSMISSION

(START + SLAVE @)

INITIATE RECEPTION

(START + SLAVE @ with LSB set)

LAST DATA

TO RECEIVE

yes

no

RECEIVE NEXT BUFFER DATA

SET THE STOP CONDITION BIT

SET THE STOP CONDITION BIT

no

yes

Write data from ST7 to EEPROM

Read data from EEPROM to ST7

END OF

RECEPTION

yes

CLEAR ACKNOWLEDGE BIT

2nd LAST DATA

TO RECEIVE

no