CY3672-USB datasheet(9/18 Pages) CYPRESS

9 / 18 page

CY22150

Document #: 38-07104 Rev. *K

Page 9 of 18

I2C Interface Timing

The CY22150 uses a two-wire I2C-interface that operates up to

400 kbits/second in Read or Write mode. The basic Write serial

format is as follows.

Start Bit; seven-bit Device Address (DA); R/W Bit; Slave Clock

Acknowledge (ACK); eight-bit Memory Address (MA); ACK;

eight-bit data; ACK; eight-bit data in MA + 1 if desired; ACK;

eight-bit data in MA+2; ACK; and so on until STOP bit.The basic

serial format is illustrated in Figure 4 on page 9.

Data Valid

Data is valid when the Clock is HIGH, and may only be transi-

tioned when the clock is LOW, as illustrated in Figure 3.

Data Frame

Every new data frame is indicated by a start and stop sequence,

as illustrated in Figure 5 on page 10.

Start Sequence – Start frame is indicated by SDAT going LOW

when SCLK is HIGH. Every time a Start signal is given, the next

eight-bit data must be the device address (seven bits) and a R/W

bit, followed by register address (eight bits) and register data

(eight bits).

Stop Sequence – Stop frame is indicated by SDAT going HIGH

when SCLK is HIGH. A Stop frame frees the bus for writing to

another part on the same bus or writing to another random

Acknowledge Pulse

During Write mode, the CY22150 responds with an ACK pulse

after every eight bits. This is accomplished by pulling the SDAT

line LOW during the N*9th clock cycle, as illustrated in Figure 6

on page 10. (N = the number of eight-bit segments transmitted.)

During Read mode, the ACK pulse after the data packet is sent

is generated by the master

Figure 3. Data Valid and Data Transition Periods

SDAT

SCLK

Data valid

Transition to next bit

CLKLOW

CLKHIGH

VIH

VIL

tSU

tDH

Figure 4. Data Frame Architecture

SDAT Write

Start Signal

Device

Address

7-bit

R/W = 0

1-bit

8-bit

Address

Slave

1-bit

ACK

Slave

1-bit

ACK

8-bit

Data

Stop Signal

Multiple

Contiguous

Registers

Slave

1-bit

ACK

8-bit

Data

(XXH)

(XXH+1)

Slave

1-bit

ACK

8-bit

Data

(XXH+2)

Slave

1-bit

ACK

8-bit

Data

(FFH)

Slave

1-bit

ACK

8-bit

Data

(00H)

Slave

1-bit

ACK

Slave

1-bit

ACK

SDAT Read

Start Signal

Device

Address

7-bit

R/W = 0

1-bit

8-bit

Address

Slave

1-bit

ACK

Slave

1-bit

ACK

7-Bit

Device

Stop Signal

Multiple

Contiguous

Registers

1-bit

R/W = 1

8-bit

Data

(XXH)

Address (XXH)

Master

1-bit

ACK

8-bit

Data

(XXH+1)

Master

1-bit

ACK

8-bit

Data

(FFH)

Master

1-bit

ACK

8-bit

Data

(00H)

Master

1-bit

ACK

Master

1-bit

ACK

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