USB3803 datasheet(44/99 Pages) MICROCHIP

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USB3803

DS00001691B-page 44

 2014-2015 Microchip Technology Inc.

6.3.2

SEQUENTIAL ACCESS READS

The I2C interface will support direct reading of the USB3803 registers. In order to read one or more register addresses,

the starting address must be set by using a write sequence followed by a read. The read register interface supports

auto-increment mode. The master should send a NACK instead of an ACK when the last byte has been transferred.

In this operation, following the 7-bit slave address, 8-bit register address is written indicating the start address for

sequential read operation to be followed. In the read sequence, every data access is a data read from a data register

where the register address increments after each access. Write sequence can end with optional Stop (P). If so the Read

sequence must start with a Start (S) otherwise it must start with Repeated Start (Sr).

Figure 6-3 shows the format of the read operation. Where color is visible in the figure, blue and gold indicate signaling

from the I2C master, and gray indicates signaling from the USB3803 slave.

6.3.3

I2C TIMING

Below is the timing diagram and timing specifications for the different I2C modes that the USB3803 supports.

FIGURE 6-3:

SEQUENTIAL ACCESS READ FORMAT

FIGURE 6-4:

I2C TIMING DIAGRAM

7 - B i t S l a v e

A ddr es s

xx xx xx xx

Re g i s t e r

A d dr es s

( b i t s

7- 0)

O p t i ona l . I f pr es ent , N e x t

ac c e s s

m u s t hav e

S t ar t ( S ) ,

o t he r w i s e

R epe at S t a r t ( S r )

7 - B i t S l av e A ddr es s

n n n n n n n n

AC K

R egi s t er v a l ue

f o r xx xxx xxx

n n n n n n n n

AC K

R egi s t er v a l u e

f o r xx xxx xxx + 1

...

n n n n n n n n

NA C K

I f pr ev i ous w r i t e s e t t i ng up

R e g i s t er addr es s end ed w i t h a

S t o p ( P ) , o t h e r w i s e it w ill b e

R e p eat ed S t a r t ( S r )

R egi s t er v a l ue

f o r xxx xxx xx + y

tHD;STA

tSU;STO

tSU;STA

tSU;DAT

tHIGH

tLOW

tHD;DAT

tHD;STA

tBUF

AB_DATA

AB_CLK

I2C_CLK

I2C_DATA

USB3803 Datasheet(PDF) 44 Page - Microchip Technology

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