UM10574 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
User manual Rev. 1 — 1 April 2014 8 of 14
NXP Semiconductors
UM10574
PCA9685 demonstration board OM13332
7. OM13332 demonstration board main components
8. PCA9685 evaluation steps
The PCA9685 functions are controlled by WIN-I2CUSB Lite GUI. Refer to the PCA9685
data sheet for additional information on the registers and functionality.
Connect the hardware as described in Section 4
. The PCA9685 demo board address is
set to 0x80 on DIP switch (S1) as A[0:5] = S1[1:6] = 000000 (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 on the 3.3 V or 5.0 V symbols on the bottom of the window. Power
supplies are disabled by default and you must enable them 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 the frequency symbol on the bottom of the window.
8.1 Dimming and brightness control for individual LED
The PCA9685 has 4096 steps (12-bit PWM) of individual LED brightness control to vary
from fully off (default) to maximum brightness. The LED output frequency (all LEDs)
typically varies from 24 Hz to 1526 Hz (default of 1Eh in PRE_SCALE register results in a
197 Hz refresh rate with oscillator clock of 25 MHz). The duty cycle of PWM can be
controlled independently using the ‘LEDn ON’ and ‘LEDn OFF’ registers. The resolution
for the phase shift is
1
⁄
4096
of the target frequency.
1. From the ‘Device’ drop-down menus, select ‘LED Blinkers and Dimmers’, and from
the subsequent drop-down menu select ‘PCA9685 16-channel LED Driver with 12-bit
PWM’ as shown in Figure 5
.
2. The device address is set to ‘80’ hexadecimal and cannot change. 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).
Table 1. OM13332 demo board main components
Device Description Address/LED output Location
PCA9685PW 16-channel, 12-bit PWM Fm+ I
2
C-bus
25 mA voltage switch LED driver
0x80 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 PCA9685 power supply
either 3.3 V or 5 V indicator
-D1
