7220 datasheet(202/303 Pages) RENESAS

202 / 303 page

APPLICATION

5.5 Example of I2C-BUS control by software (M37220M3-XXXSP/FP)

7220 Group User’s Manual

5-29

(2)

Read processing routine

Fig. 5.5.5 Flowchart of read processing routine

“WRITEDATA”

←Slave address (W) “A0 16”

“F_ACK” = “0”?

Data output

Yes (ACK)

“NO ACK COUNTER” = “0”

START condition

“WRITEDATA”

←Sub-address

“F_ACK” = “0”?

Yes (ACK)

No (no ACK)

Read start

RAM:

Flag:

WRITEDATA

NO ACK COUNTER

READ DATA COUNTER

F_ACK

Slave address

(W) “A016”

Sub-address

Data

Slave address

(R) “A116”

To M52340SP ?

(See note 2)

No (to other devices (cf. E 2PROM))

Yes (sub-address is not necessary at reading)

End

“READ DATA

COUNTER” = “0”?

Yes (end)

No (not yet)

Return NACK

STOP condition

Return ACK

“READ DATA COUNTER”

←“READ DATA COUNTER” – 1

Data input

“NO ACK COUNTER”

←“NO ACK COUNTER” + 1

STOP condition

“NO ACK COUNTER”

≥ “3”?

Yes (give up)

No (try 3 times)

Data output

START condition

“WRITEDATA”

←Slave address (R) “A1 16”

“F_ACK” = “0”?

Yes (ACK)

No (no ACK)

Bus H

Notes 1: NACK = No ACK

Branches according to whether the

device needs sub-address or not.

(See note 1)

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