NXP Semiconductors PCA9955BTW-ARD, User Manual, Page: 7 / 38

NXP Semiconductors
UM11761
PCA9955BTW-ARD evaluation board
chain configuration (J45 / J89, see Section 4.7 ), and the on-board LEDs, connected to
the output of the DUT (U2).
Figure 2. PCA9955BTW-ARD block diagram
The PCA9959B is controlled through an I
2
C interface. The motherboard (EVK) uses an
I
2
C-bus to control the PCA9955BTW-ARD daughterboard through the Arduino port. The
blue lines in the drawing refer to the I
2
C-bus. From the Arduino connector J35, the I
2
C
lines are connected to the SDA / SCL pins of the DUT (U2, pin 26, and 27), and to the
expansion connectors J45 and J89. For more details, see the schematic diagram of the
PCA9955BTW-ARD board.
The target address of the PCA9955B can be configured for 125 different target
addresses, by unique combination of five states to three address inputs of the IC (U2, pin
2, 3, and 4). For details, see PCA9955B datasheet (NXP Semiconductors). The jumper
headers J86, J87 and J88, allow to select only 27 from 125 possible addresses. Table 1
depicts the target address depending on the position of the address jumpers. Note that
the default selected address is BCh.
J88 position J87 position J86 position I
2
C target address (HEX)
1-2 1-2 1-2 BCh (default)
1-2 1-2 2-3 B8h
1-2 1-2 OFF BAh
1-2 2-3 1-2 A8h
1-2 2-3 2-3 A4h
1-2 2-3 OFF A6h
1-2 OFF 1-2 B2h
1-2 OFF 2-3 AEh
Table 1. I
2
C target address chart
UM11761 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2022. All rights reserved.
User manual Rev. 1.0 — 18 March 2022
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