PCA9554 查看數據表（PDF） - ON Semiconductor
零件编号
产品描述 (功能)
生产厂家
PCA9554 Datasheet PDF : 11 Pages
| |||
PCA9554
The output port register sets the outgoing logic levels of
the I/O ports, defined as outputs by the configuration
register. Bit values in this register have no effect on I/O pins
defined as inputs. Reads from the output port register reflect
the value that is in the flip−flop controlling the output, not
the actual I/O pin value.
The polarity inversion register allows the user to invert the
polarity of the input port register data. If a bit in this register
is set (“1”) the corresponding input port data is inverted. If
a bit in the polarity inversion register is cleared (“0”), the
original input port polarity is retained.
The configuration register sets the directions of the ports.
Set the bit in the configuration register to enable the
corresponding port pin as an input with a high impedance
output driver. If a bit in this register is cleared, the
corresponding port pin is enabled as an output. At
power−up, the I/Os are configured as inputs with a weak
pull−up resistor to VCC.
Data is transmitted to the PCA9554’s registers using the
write mode shown in Figure 9 and Figure 10.
The PCA9554’s registers are read according to the timing
diagrams shown in Figure 11 and Figure 12. Once a
command byte has been sent, the register which was
addressed will continue to be accessed by reads until a new
command byte will be sent.
SCL 1 2 3 4 5 6 7 8 9
slave address R/W
command byte
SDA S 0 1 0 0 A2 A1 A0 0 A 0 0 0 0 0 0 0 1 A
start condition
WRITE TO
PORT
acknowledge
from slave
acknowledge from slave
data to port
DATA 1
acknowledge from slave
AP
stop
condition
DATA OUT FROM PORT
Figure 9. Write to Output Port Register
DATA 1 VALID
tpv
SCL 1 2 3 4 5 6 7 8 9
slave address R/W
command byte
SDA S 0 1 0 0 A2 A1 A0 0 A 0 0 0 0 0 0 1 1/0 A
start condition
WRITE TO
REGISTER
acknowledge
from slave
acknowledge from slave
data to register
DATA 1
acknowledge from slave
AP
stop
condition
Figure 10. Write to Configuration or Polarity Inversion Register
www.onsemi.com
9
Share Link: 