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User manual Rev. 1 — 7 June 2012 8 of 16
NXP Semiconductors
UM10572
PCA9955 demonstration board OM13330
7. OM13330 demonstration board main components
8. PCA9955 evaluation steps
The PCA9955 functions are controlled by WIN-I2CUSB Lite GUI. Refer to the PCA9955
data sheet for additional information on the registers and functionality.
Connect the hardware as described in Section 4 . The PCA9955 demo board address is
set to 0xC0 on SW1 as A[0:3] = SW1[1:4] = 0000 (0
→
ON, 1
→
OFF). When you have
correctly installed the software and the demonstration board hardware is connected and
recognized by the computer, start the Win-I2CUSB Lite software. As shown in
Figure 5 ,
when the demonstration board hardware is correctly connected to the USB port and the
computer recognizes it, the message ‘Hardware Detected’ is displayed on the bottom of
the window.
Switched 3.3 V and 5.0 V power supplies are controlled through the ‘Options’ menu or by
double-clicking the 3.3 V or 5.0 V symbols on the bottom of the window. Power supplies
are disabled by default, and must be enabled before using the I
2
C-bus devices on the
board. I
2
C-bus frequency is controlled through the ‘Options’ menu or by double-clicking on
the frequency symbol on the bottom of the window.
8.1 Color mixing and dimming LEDs
1. From the ‘Device’ drop-down menus, select ‘LED Blinkers and Dimmers’, and from
the subsequent drop-down menu select ‘PCA9955 16-channel Constant Current LED
Driver’ as shown in
Figure 5 .
2. Check the ‘Auto Write On’ box (lower left), uncheck the ‘Low power mode (oscillator
off)’ box to enable the device to ‘Normal mode’ (upper left).
3. The device configuration screen is displayed by clicking the following options:
– ‘PWM 0 to 7’ individual brightness control for LED0 to LED7 as shown in Figure 6 .
– ‘PWM 8 to 15’ individual brightness control for LED8 to LED15 as shown in
Figure 7 .
– ‘LEDOUT’ LED driver output state for LED0 to LED15 as shown in Figure 8 .
– ‘Output Gain’ LED output current setting for LED0 to LED15 as shown in Figure 9 .
Table 1. OM13330 demo board main components
Device Description Address/LED output Location
PCA9955TW 16-channel Fm+ I2C-bus 57 mA
constant current LED driver 0xC0 for I2C demo board 2005-1
interface U1
LW-E67C White LED LED0, LED4, LED8, LED12 D2, D4, D6, D9
LRTB_G6SG RGB LED LED1, LED2, LED3 D3
LRTB_G6SG RGB LED LED5, LED6, LED7 D5
LRTB_G6SG RGB LED LED9, LED10, LED11 D7
LRTB_G6SG RGB LED LED13, LED14, LED15 D8
LTST-C170KGKT Green LED for PCA9955 power supply
either 3.3 V or 5 V indicator - D1