MAS6505 datasheet(31/44 Pages) MAS

31 / 44 page

DA6505.005

11 June 2018

31 (44)

2-WIRE SERIAL DATA INTERFACE (I2C BUS)

Figure 7. I2C bus protocol definitions

Bus communication includes Acknowledge (A) and

not Acknowledge (N) messages. To send an

acknowledge the receiver device pulls the SDI low

for one SCK clock cycle. For not acknowledge (N)

the receiver device leaves the SDI high for one SCK

clock cycle in which case the master can then

generate either a Stop (P) bit to abort the transfer, or

a repeated Start (Sr) bit to start a new transfer.

Abbreviations:

A= Acknowledge

N = Not Acknowledge

S = Start

Sr = Repeated Start

P = Stop

= from Master (MCU) to Slave (MAS6505)

= from Slave (MAS6505) to Master (MCU)

Measurement Configuration and Starting

– Write Sequence

Prior starting measurements a suitable configuration

setup should be written to the Configuration register

(EE/6EHEX). Actual A/D conversion is started by

writing measurement setup into the Control register

(EFHEX). The Control register write sequence is

illustrated in Table 13. Since Configuration and

control register addresses are consecutive it is also

possible to write both registers in the same write

sequence by utilizing the incremental write feature of

MAS6505. This is illustrated in the table 14.

Table 13. MAS6505 I2C bus write sequence of Control register

ACT

DCT

Table 14. MAS6505 I2C bus incremental write sequence of both Configuration and Control registers

ACF

DCF

DCT

Abbreviations:

AW = Device write address EAHEX (%1110 1010)

AR = Device read address EBHEX (%1110 1011)

ACF = Configuration reg. addr. EEHEX (%1110 1110)

ACT = Control reg. addr. EFHEX (%1110 1111)

DCF=Data of Configuration register

DCT=Data of Control register

Ax = Address of non-specified register

Dx = Data of non-specified register

AP = MSB register address of pressure result (F1HEX,

%1111 0001)

AT = MSB register address of temperature result

(F4HEX, %1111 0100)

Dxy = Data

measurement

result

temperature (x=T), pressure (x=P), MSB (y=M), LSB

(y=L) or XLSB (y=X)

Each serial bus operation, like write, starts with the

start (S) bit (see Figure 7). After start (S) the

MAS6505 device address with write bit (AWTable )

is sent followed by an Acknowledge (A). Next the

target register address is sent and followed by an

Acknowledge (A). Then the data is written one byte

at a time. Each byte is followed by an Acknowledge

(A). The serial bus operation is ended with stop (P)

command (see Figure 7). The MAS6505 starts

configured measurement right after receiving the

Configuration register (EEHEX) bits.

SDI

SCK

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