mpr081 Freescale Semiconductor, Inc, mpr081 Datasheet - Page 8

• Manufacturer Part Number: mpr081
• Description: Touch Pad Controller
• Manufacturer: Freescale Semiconductor, Inc

MPR081
8
ACKNOWLEDGE
the recipient uses to handshake receipt of each byte of data.
Thus each byte transferred effectively requires 9 bits. The
master generates the 9
down SDA during the acknowledge clock pulse, such that the
THE SLAVE ADDRESS
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
START condition followed by its slave address. When a
MPR081 recognizes its slave address, it acknowledges and
is then ready for continued communication.
MESSAGE FORMAT FOR WRITING THE MPR081
MPR081's keyscan slave address with the R/W bit set to 0,
The acknowledge bit is a clocked 9th bit
The MPR081 has a 7-bit long slave address
The MPR081 monitors the bus continuously, waiting for a
A write to the MPR081 comprises the transmission of the
th
clock pulse, and the recipient pulls
(Figure
Figure 9. Command Byte Received
(Figure
Figure 8. Slave Address
7) which
Figure 7. Acknowledge
5).
SDA line is stable low during the high period of the clock
pulse. When the master is transmitting to the MPR081, the
MPR081 generates the acknowledge bit because the
MPR081 is the recipient. When the MPR081 is transmitting to
the master, the master generates the acknowledge bit
because the master is the recipient.
command. The MPR081 has a factory set I²C slave address
which is normally 1001100 (0x4C). Contact the factory to
request a different I
range 0001000 to 1110111 (0x08 to 0xEF).
followed by at least one byte of information. The first byte of
information is the command byte. The command byte
determines which register of the MPR081 is to be written by
the next byte, if received. If a STOP condition is detected after
the command byte is received, then the MPR081 takes no
further action
Any bytes received after the command byte are data bytes.
(Figure
2
C slave address, which is available in the
9) beyond storing the command byte.
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