PIC17LC752-08/JWQTP View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC17LC752-08/JWQTP

High-Performance 8-Bit CMOS EPROM Microcontrollers

Microchip Technology 

PIC17C75X

Figure E-6 and Figure E-7 show Master-transmitter

and Master-receiver data transfer sequences.

When a master does not wish to relinquish the bus (by

generating a STOP condition), a repeated START con-

dition (Sr) must be generated. This condition is identi-

cal to the start condition (SDA goes high-to-low while

SCL is high), but occurs after a data transfer acknowl-

edge pulse (not the bus-free state). This allows a mas-

ter to send “commands” to the slave and then receive

the requested information or to address a different

slave device. This sequence is shown in Figure E-8.

FIGURE E-6: MASTER-TRANSMITTER SEQUENCE

For 7-bit address:

For 10-bit address:

S Slave Address R/W A Data A Data A/A P

'0' (write)

data transferred

(n bytes - acknowledge)

S Slave Address R/W A1 Slave Address A2

First 7 bits

Second byte

(write)

A master transmitter addresses a slave receiver with a

7-bit address. The transfer direction is not changed.

Data A Data A/A P

From master to slave

From slave to master

A = acknowledge (SDA low)

A = not acknowledge (SDA high)

S = Start Condition

P = Stop Condition

A master transmitter addresses a slave receiver

with a 10-bit address.

FIGURE E-7: MASTER-RECEIVER SEQUENCE

For 7-bit address:

For 10-bit address:

S Slave Address R/W A Data A Data A P

'1' (read)

data transferred

(n bytes - acknowledge)

S Slave Address R/W A1 Slave Address A2

First 7 bits

Second byte

(write)

A master reads a slave immediately after the first byte.

From master to slave

From slave to master

A = acknowledge (SDA low)

A = not acknowledge (SDA high)

S = Start Condition

P = Stop Condition

Sr Slave Address R/W A3 Data A Data A P

First 7 bits

(read)

A master transmitter addresses a slave receiver

with a 10-bit address.

FIGURE E-8:

COMBINED FORMAT

(read or write)

(n bytes + acknowledge)

S Slave Address R/W A Data A/A Sr Slave Address R/W A Data A/A P

(read)

Sr = repeated (write)

Start Condition

Direction of transfer

may change at this point

Transfer direction of data and acknowledgment bits depends on R/W bits.

Combined format:

Sr Slave Address R/W A Slave Address A Data A

First 7 bits

Second byte

(write)

Data A/A Sr Slave Address R/W A Data A

First 7 bits

(read)

Data A P

Combined format - A master addresses a slave with a 10-bit address, then transmits

data to this slave and reads data from this slave.

From master to slave

From slave to master

A = acknowledge (SDA low)

A = not acknowledge (SDA high)

S = Start Condition

P = Stop Condition

© 1997 Microchip Technology Inc.

Preliminary

DS30264A-page 269

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