Datasheet

PCA9538 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 7 — 26 November 2014 7 of 34
NXP Semiconductors
PCA9538
8-bit I
2
C-bus and SMBus low power I/O port with interrupt and reset
6.2.3 Register 1 - Output Port register
This register reflects the outgoing logic levels of the pins defined as outputs by Register 3.
Bit values in this register have no effect on pins defined as inputs. Reads from this register
return the value that is in the flip-flop controlling the output selection, not the actual pin
value.
6.2.4 Register 2 - Polarity Inversion register
This register allows the user to invert the polarity of the Input Port register data. If a bit in
this register is set (written with 1), the corresponding Input Port data is inverted. If a bit in
this register is cleared (written with a 0), the Input Port data polarity is retained.
Table 6. Register 1 - Output Port register bit description
Legend: * default value.
Bit Symbol Access Value Description
7 O7 R 1* reflects outgoing logic levels of pins defined as outputs
by Register 3
6O6 R 1*
5O5 R 1*
4O4 R 1*
3O3 R 1*
2O2 R 1*
1O1 R 1*
0O0 R 1*
Table 7. Register 2 - Polarity Inversion register bit description
Legend: * default value.
Bit Symbol Access Value Description
7 N7 R/W 0* inverts polarity of Input Port register data
0 = Input Port register data retained (default value)
1 = Input Port register data inverted
6N6 R/W0*
5N5 R/W0*
4N4 R/W0*
3N3 R/W0*
2N2 R/W0*
1N1 R/W0*
0N0 R/W0*