MIC24045 datasheet(38/46 Pages) MICROCHIP

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MIC24045

DS20005568A-page 38

 2016 Microchip Technology Inc.

8.5.4

BLOCK READ (AUTO INCREMENT

MODE)

This command reads a block of bytes, starting from a

designated register that is specified through the com-

mand byte. Bit<6> of the command byte indicates the

Auto-Increment mode. If this bit is set, the address gets

incremented by one automatically and the registers are

read in order, starting from the address provided by the

command byte.

The Block/Auto-Increment Read command is as

follows and it is illustrated in the timing diagram of

Figure 8-6.

Send START sequence

Send 7-bit slave address

Send the R/W bit - 0 to indicate a write operation

Wait for acknowledge from the slave

Send the command byte – address that needs to

be read with Bit<6> set high to indicate the

Auto-Increment Read mode.

Wait for acknowledge from the slave

Send START sequence again

Send the 7-bit slave address

Send R/W bit - 1 to indicate a read operation

10. Wait for acknowledge from the slave

11. Receive the 8-bit data from the slave register

indicated in step 5, starting from MSB

12. Acknowledge from the master receiver. On the

last byte, master receiver issues a NACK in

place of ACK to signal the end of the data

transfer.

13. Repeat steps 11 and 12 until last byte

14. STOP sequence is sent

FIGURE 8-6:

Block Read Timing Diagram.

In Block Read Auto-Increment mode, the master

receiver must signal an end-of-data to the transmitter

by not generating an acknowledge on the last byte that

has been clocked out of the slave. In this event, the

transmitter must leave the data line HIGH to enable the

master to generate a STOP condition.

If the master keeps reading beyond the valid

user-accessible register locations, the content of inter-

nal test registers will be streamed out until location

15 (Fh) is reached. After that, the read operation

wraps-around and restarts from register location 0h

and so on, until the master stops reading.

SDA

START condition

ACK from Slave

Slave address

Command byte

ACK from Slave

(repeated)

START condition

R/W

ACK from Slave

Slave address

Data from register X+n

STOP condition

DATA (first byte)

R/W

At this moment master-transmitter becomes master-receiver

and slave-receiver becomes slave-transmitter

* * *

(cont.)

* * *

(cont.)

* * *

Data from register X

DATA (first byte)

Data from register X+1

DATA (first byte)

Note:

If the master is using a non-existing regis-

ter location in the command byte, a reject

(NACK) will be generated by the

MIC24045.

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