Freescale Semiconductor Evaluation Board MPR031/2 for 2- or 3-pad touch sensor controllers DEMOMPR031 DEMOMPR031 データシート

製品コード

DEMOMPR031

MPR03X

Sensors
Freescale Semiconductor

2.3.3

Bit Transfer

One data bit is transferred during each clock pulse (

Figure 7

). The data on SDA must remain stable while SCL is high.

Figure 7. Stop and Start Conditions

2.3.4

Acknowledge

The acknowledge bit is a clocked 9

bit (

Figure 8

) which the recipient uses to handshake receipt of each byte of data. Thus each

byte transferred effectively requires 9 bits. The master generates the 9

clock pulse, and the recipient pulls down SDA during

the acknowledge clock pulse, such that the SDA line is stable low during the high period of the clock pulse. When the master is
transmitting to the MPR03X, the MPR03X generates the acknowledge bit, since the MPR03X is the recipient. When the MPR03X
is transmitting to the master, the master generates the acknowledge bit, since the master is the recipient.

Figure 8. Acknowledge

2.3.5

The Slave Address

The MPR03X has a 7-bit long slave address (

Figure 9

). The bit following the 7-bit slave address (bit eight) is the R/W bit, which

is low for a write command and high for a read command.

Figure 9. Slave Address

The MPR03X monitors the bus continuously, waiting for a START condition followed by its slave address. When a MPR03X
recognizes its slave address, it acknowledges and is then ready for continued communication.

The MPR031 and MPR032 slave addresses are show in

Table 2

Table 2.

Part Number

C Address

MPR031

0x4A

MPR032

0x4B

START

CONDITION

SDA

SCL

STOP

CONDITION

START

CONDITION

SDA

BY TRANSMITTER

CLOCK PULSE FOR

ACKNOWLEDGEMENT

SDA

BY RECEIVER

SCL

SDA

R/W

ACK

MSB

SCL