mpr081 Freescale Semiconductor, Inc, mpr081 Datasheet - Page 7

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

Sensors
Freescale Semiconductor
SERIAL-ADDRESSING
data through an I
serial data line (SDA) and a serial clock line (SCL) to achieve
open-drain output. A pull-up resistor, typically 4.7 k:, is
required on SDA. The MPR081 SCL line operates only as an
input. A pull-up resistor, typically 4.7 k:, is required on SCL if
there are multiple masters on the 2-wire interface, or if the
START AND STOP CONDITIONS
busy. A master signals the beginning of a transmission with a
START (S) condition by transitioning SDA from high to low
while SCL is high. When the master has finished
communicating with the slave, it issues a STOP (P) condition
The MPR081 operates as a slave that sends and receives
The MPR081 SDA line operates as both an input and an
Both SCL and SDA remain high when the interface is not
2
C 2-wire interface. The interface uses a
Figure 4. 2-Wire Serial Interface Timing Details
Figure 5. Start and Stop Conditions
SERIAL INTERFACE
Figure 6. Bit Transfer
bi-directional communication between master(s) and
slave(s). A master (typically a microcontroller) initiates all
data transfers to and from the MPR081 and generates the
SCL clock that synchronizes the data transfer.
master in a single-master system has an open-drain SCL
output.
(Figure
slave address plus R/W bit, a register address byte, one or
more data bytes, and finally a STOP condition.
by transitioning SDA from low to high while SCL is high. The
bus is then free for another transmission.
BIT TRANSFER
(Figure
high.
Each transmission consists of a START condition
One data bit is transferred during each clock pulse
5) sent by a master, followed by the MPR081's 7-bit
6). The data on SDA must remain stable while SCL is
MPR081
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