S-7750C

Seiko Instruments Inc.

10

Device Addressing

To start communication, the master device (MPU) on the system generates a start condition for the slave device

(S-7750C). After that, the master device sends a device address with 7-bit and Read / Write instruction code with 1-bit

on the SDA bus. The higher 3 bits in a device address (DC2, DC1, DC0) are device codes. The fixed value which users

selected by option (either one of 000, 001, 010, 011, 100, 101, 110, 111) is a device code. Command is omitted if a

device code does not correspond. The next 1-bit

C

TA /

is a bit for timer address setting / command switch.

When

C

TA /

= “1”, the next 3 bits (C2, C1, C0) are used as address, when

C

TA /

= “0”, (C2, C1, C0) are used as

command for the timer setting register.

Address /

command

DC2

DC1

DC0

TA / C

C2

C1

C0

R / W

Device

Code

MSB

LSB

Read / Write bit

ACK

Acknowledgment

Signal

STA

Start

Condition

B7

B6

B5

B4

B3

B2

B1

B0

MSB

LSB

ACK

STP

Register data

Stop

Condition

Timer address setting /

command switch

Figure 10 Device Addressing