DA6512.003
2 December, 2016
2-WIRE SERIAL DATA INTERFACE (I2C BUS)
Figure 4. I2C bus protocol definitions
Bus communication includes Acknowledge (A) and
not Acknowledge (N) messages. To send an
acknowledge the receiver device pulls the SDA low
for one SCL clock cycle. For not acknowledge (N)
the receiver device leaves the SDA high for one
SCL 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 by Receiver
N = Not Acknowledge by Receiver
S = Start
P = Stop
= from Master (MCU) to Slave (MAS6512)
= from Slave (MAS6512) to Master (MCU)
Sr = Repeated Start
Conversion Starting – Write Sequence
Conversion is started by writing configuration bits
into the Measurement control register (address
E2HEX). The write sequence is illustrated in Table
12.
Table 12. MAS6512 I2C bus write sequence of Measurement control register
AW MC DC
S
A
A
A
P
Abbreviations:
AW = Device Write Address ECHEX (%1110 1100)
AR = Device Read Address EDHEX (%1110 1101)
MC = Meas. control register 62HEX (%0110 0010)
Ax = Conversion Result Registers’ Addresses; MSB
(x=M, 6AHEX %0110 1010), LSB (x=L, 6BHEX %0110
1011)
DC = Measurement Control Register Data
Dx = Conversion Result Register Data; MSB (x=M),
LSB (x=L)
Each serial bus operation, like write, starts with the
start (S) bit (see figure 4). After start (S) the
MAS6512 device address with write bit (AW, see
table 11) is sent followed by an Acknowledge (A).
After this the Measurement control register address
(see table 1) is sent and followed by an
register data (DC, see table 3) is written and
followed by an Acknowledge (A). Finally the serial
bus operation is ended with stop (P) command (see
figure 4). A new A/D conversion starts right after
Measurement control register bits containing
SCO=1 are received.
Acknowledge (A). Next the Measurement control
A/D Conversion
After power on reset or external reset (XCLR) the
EOC output is high. After an A/D conversion is
started the EOC output is set low until the
conversion is finished and the EOC goes back high,
indicating that the conversion is done and data is
ready for reading. The EOC is set low only by
starting a new conversion. To save power the
internal oscillator runs only during conversion.
During an A/D conversion the input signal is
sampled continuously leading to an output
conversion result that is a weighted average of the
samples taken.
19 (32)
MAS [ MICRO ANALOG SYSTEMS ]
