DA6505.005
11 June 2018
2-WIRE SERIAL DATA INTERFACE (I2C BUS)
S
P
1
0
SDI
SCK
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
P = Stop
= from Master (MCU) to Slave (MAS6505)
= from Slave (MAS6505) to Master (MCU)
Sr = Repeated Start
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
AW ACT DCT
S
A
A
A
P
Table 14. MAS6505 I2C bus incremental write sequence of both Configuration and Control registers
S
AW
A
ACF
A
DCF
A
DCT
A
P
Abbreviations:
AW = Device write address EAHEX (%1110 1010)
AR = Device read address EBHEX (%1110 1011)
AP = MSB register address of pressure result (F1HEX
%1111 0001)
,
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
AT = MSB register address of temperature result
(F4HEX, %1111 0100)
Dxy = Data of measurement result register;
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.
31 (44)
MAS [ MICRO ANALOG SYSTEMS ]
