NXP Semiconductors UM10574 User manual

UM10574
PCA9685 demonstration board OM13332
Rev. 1 — 1 April 2014 User manual
Document information
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Keywords Fm+ I2C-bus, PCA9685, RGB and White LEDs, 16 channel x 12-bit PWMs
Abstract The OM13332 is an add-on to 9-pin connector of the NXP I2C demo board 2005-1
or Fm+ I2C Bus development board. This daughter board makes it easy to test
and design with the PCA9685, the LED output driver is programmed to be either
open-drain with a 25 mA current sink capability at 5 V or totem pole with a 25 mA
sink. The PCA9685 operates with a supply voltage range of 2.3 V to 5.5 V and the
inputs and outputs are 5.5 V tolerant. This demo board, along with the
Win-I2CUSB Lite GUI (PC based), provides an easy to use evaluation platform.

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Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
NXP Semiconductors UM10574
PCA9685 demonstration board OM13332
Revision history
Rev Date Description
1.0 20140401 user manual; initial release

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PCA9685 demonstration board OM13332
1. Introduction
The PCA9685 evaluation board features LEDs for color backlighting and Ambilight
demonstrations. A graphical interface allows the user to explore the different functions of
the driver easily. The board can be connected in series with other I2C demo-boards to
create an evaluation system.
The IC communicates to the host via the industry standard I2C-bus/SMBus port. The
evaluation software runs under Microsoft Windows PC platform.
2. Features
•A complete evaluation platform for the PCA9685 16-channel, 12-bit PWM Fm+
I2C-bus 25 mA voltage switch LED driver
•Easy to use GUI-based software demonstrates the capabilities of the PCA9685
•On-board RGB and White LEDs for visual experience
•Convenient test points for easy scope measurements and signal access
•USB interface to the host PC
•No external power supply required
3. Getting started
3.1 Assumptions
Familiarity with the I2C-bus is helpful but not required.
3.2 Static handling requirements
3.3 Minimum system requirements
•PC Pentium 60 processor (or equivalent), 8 MB RAM, 10 MB of hard drive space
•One USB port (either 2.0 or 1.1 compatible)
•Windows 98SE, ME, 2000, XP, or Vista
•I2C demonstration board 2005-1 (OM6275) or WIN-I2CUSB board (from
www.demoboard.com).
3.4 Power requirements
The NXP demonstration board I2C 2005-1 and OM13332 hardware obtain power from the
PC USB port. Take care not to exceed the USB port current capabilities.
CAUTION
This device is sensitive to ElectroStatic Discharge (ESD). Therefore care should be taken
during transport and handling. You must use a ground strap or touch the PC case or other
grounded source before unpacking or handling the hardware.

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PCA9685 demonstration board OM13332
4. Installation
4.1 I2C demo board 2005-1 and WIN-I2CUSB Lite software
The OM13332 is a daughter card to the OM6275 I2C demo board 2005-1. You can
download the WIN-I2CUSB Lite Software, the OM6275 user manual UM10206, and find
ordering information at the NXP web site www.nxp.com/demoboard/OM6275.html.
The Win-I2CUSB Lite software from The Boardshop runs on Windows 98SE, ME, 2000,
and XP, and is compatible with any PC hardware having a minimum of a Pentium
processor and a USB port. The software allows the user to select one of the I2C-bus
devices on the board from a menu and also provides a Universal mode (I2C Expert mode)
to allow users to create their own I2C-bus commands with the same I2C-bus devices.
4.2 OM13332 connection to I2C demo board 2005-1
The I2C demo board 2005-1 should be disconnected from your PC before mounting the
OM13332 board on to it. The OM13332 board has a 9-pin female connector (J2) that
connects to the JP1 male connector on the I2C demo board 2005-1 as shown in Figure 1.
With both boards facing you, with USB connector on the left-hand side as shown in
Figure 1, connect the OM13332 board to the I2C demo board 2005-1 before connecting
the USB cable. Once the board is connected, connect the USB cable and start the
WIN-I2CUSB Lite software. You are now ready to evaluate the PCA9685.
Fig 1. PCA9685 demo board (OM13332) mounting to the I2C demo board 2005-1 (OM6275)

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PCA9685 demonstration board OM13332
4.3 OM13332 connection to Win-I2CUSB hardware adapter board
The Win-I2CUSB board should be disconnected from your PC before connecting the
OM13332 board on to it. The OM13332 board has a 14-pin male connector (J4) that
connects to the 14-pin male connector (J1) on the Win-I2CUSB board as shown in
Figure 2.
Connect the OM13332 board to the Win-I2CUSB board before connecting the USB cable.
Once the board is connected, connect the USB cable and start the WIN-I2CUSB Lite
software. You are now ready to evaluate the PCA9685.
Fig 2. PCA9685 demo board (OM13332) connecting to the Win-I2CUSB board

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PCA9685 demonstration board OM13332
5. Hardware description
Figure 3 shows the following items on the hardware:
•J2 (9-pin) is for connection to JP1 on I2C demo board 2005-1.
•J3 (9-pin male) is for connection to the second PCA9685 demo board or I2C-bus
device.
•J1 selects VDD power for PCA9685, connected 1-2 for VDD = 3.3 V and connected 2-3
for VDD = 5 V.
•S1 8-position DIP switch to select I2C-bus address A[0:5] = S1[1:6] for this device
(default is 0x80, all switches S1[1:6] are ON position). S1[7] is used to control output
enable (/OE, default is ON position to enable LED outputs), S1[8] is used to control
EXTCLK (default is ON position to disable the EXTCLK).
•J4 (14-pin) is for connection to J1 on Win-I2CUSB board.
•4-channel to drive four White LEDs (D2, D4, D6, D9) and 12-channel to drive four
RGB LEDs (D3, D5, D7, D8).
•/OE (TP1) is input to drive output enable (pin 23) when S1[7] is set to OFF position.
•EXTCLK (TP2) is input to EXTCLK (pin 25) when S1[8] is set to OFF position.
•J5 and J6 are GND pins for probing use.
Fig 3. PCA9685 demo board (OM13332)

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PCA9685 demonstration board OM13332
6. Schematic
Fig 4. PCA9685 demo board schematic
019aac802
1
2
3
+5 V
+3.3 V
4
5
SCL_1
J2
C1
10 μF
9-pin female
connector
6
7
SDA_1
GND
8
9
C2
10 μF
9-pin connector to/from I2C 2005-1
or to/from PCA9685 demo board
3
2
1
J6
1GND
2I/O1
4
VCC
3
I/O2
U2
close to connector J2/J4
PRTR5V0U2AX
C23
0.01 μF
+5 V
L1
BLM18BD471SN1
SDA_1 SDA-filter
L2
BLM18BD471SN1
SCL_1 SCL-filter
(470 Ω at 100 MHz)
1GND
2I/O1
4
VCC
3
I/O2
U3
close to 9-pin connector J3
PRTR5V0U2AX
C24
0.01 μF
+5 V
L3
BLM18BD471SN1
SDA_2 SDA-filter
L4
BLM18BD471SN1
SCL_2 SCL-filter
(470 Ω at 100 MHz)
C7
0.1 nF
C8
0.1 nF
C9
0.1 nF
C10
0.1 nF
C11
0.1 nF
C12
0.1 nF
C13
0.1 nF
C14
0.1 nF
C15
0.1 nF
C16
0.1 nF
C17
0.1 nF
C18
0.1 nF
C19
0.1 nF
C20
0.1 nF
C21
0.1 nF
C22
0.1 nF
D2
LED0
LW-E67C-white
+5 V
A1
C2
A2
C1
C3
A3
D3 LED[1:3]
LRTB_G6SG
D4
LED4
LW-E67C-white
R10 440 Ω
R11 1.16 kΩ
R12 720 Ω
R13 720 Ω
LED0
LED1
LED2
LED3
R14 440 Ω
R15 1.16 kΩ
R16 720 Ω
LED4
LED5
LED6
R17 720 Ω
R18 440 Ω
R19 1.16 kΩ
LED7
LED8
LED9
R20 720 Ω
R21 720 Ω
R22 440 Ω
LED10
LED11
LED12
R23 1.16 kΩ
R24 720 Ω
R25 720 Ω
LED13
LED14
LED15
A1
C2
A2
C1
C3
A3
D5 LED[5:7]
LRTB_G6SG
D6
LED8
LW-E67C-white
A1
C2
A2
C1
C3
A3
D7 LED[9:11]
LRTB_G6SG
D9
LED12
LW-E67C-white
A1
C2
A2
C1
C3
A3
D8 LED[13:15]
LRTB_G6SG
3
2
1
J5
GND
GND
VP for I2C pull-up VDD
on WIN-I2CUSB board
1
2
3
4
5
A1
A2
A4
A3
A1
A2
A4
A3
A0
PCA9685PW
6
7
8
9
LED0
LED1
LED3
LED2
LED0
LED1
LED3
LED2
10
11
12
LED4
LED6
LED5 LED4
LED6
LED5
13
14
LED7 LED7
VSS
U1
28
27
26
25
24 A5
EXTCLK
SDA
SCL
A5
EXTCLK
VDD
23
22
21
20
/OE
LED15
LED13
LED14
/OE
LED15
LED13
LED14
19
18
17
LED12
LED10
LED11
LED12
LED10
LED11
16
15
LED9
LED8
LED9
LED8
SW1
SW DIP-8
R1 10 kΩ R2 10 kΩ R3 10 kΩ R4 10 kΩ
VDD_IN
(output enable)
TP2 1
SDA filter
SCL filter R9
1 kΩ
1 2 3
J1
+3.3 V +5 V
VDD_IN
C5
0.1 μF
C6
4.7 μF
D1
LTST-C170KGKT
limited the current to 2.5 mA
white LED VF= 3.9 V
red LED VF= 2.1 V
green/blue LED VF= 1.8 V
1
3
5
7
9
11
13
2
4SCL_1
(VP) VDO_IN
6
8
10
GND
SDA_1
12
14 +5 V
J4
GND
+3.3 V
14-pin connector to/from WIN-I2CUSB
Fm+ I2C master to drive PCA9685
HEADER 7x2/SM
I2CUSB CONNECTOR
A0
R5 10 kΩ R6 10 kΩ R7 10 kΩ R8 10 kΩ
A5
EXTCLK
TP1 1 /OE
(external clock in)
(switched to GND when
external clock is not used)
1
2
3
+5 V
+3.3 V
4
5SCL_2
J3
C4
10 μF
9-pin female
connector
6
7SDA_2
GND
8
9
C3
10 μF
9-pin connector to/from I2C 2005-1
or to/from PCA9685 demo board

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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 I2C-bus
devices on the board. I2C-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+ I2C-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

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PCA9685 demonstration board OM13332
3. For LED output that directly connects to LED as the demo board design, the INVRT
bit in MODE2 register must be set to 1 by checking the ‘Output not inverted’ to ‘Output
inverted’ and the OUTDRV bit in MODE2 register must be set to 0 by checking the
‘Totem pole outputs’ to ‘Open-drain outputs’ to make sure all LEDs are completed
OFF state as shown in Figure 6.
4. The device configuration screen is displayed by clicking the following options:
–‘PWM 0 to 3’ individual brightness control for LED0 to LED3
–‘PWM 4 to 7’ individual brightness control for LED4 to LED7
–‘PWM 8 to 11’ individual brightness control for LED8 to LED11
–‘PWM 12 to 15’ individual brightness control for LED12 to LED15
–‘Control Registers’ all LED[0:15] brightness control and Prescale for all LEDs
output frequency as shown in Figure 7
5. In Figure 6, uncheck the ‘LEDn Full Off’ box (lower bottom), adjust both ‘LEDn ON’
and ‘LEDn OFF’ bar for dimming/brightness effect, also move LED1 ON/OFF to
control red, LED2 ON/OFF to control green, LED3 ON/OFF to control blue for color
mixing.
Remark: The LED ON time, which is programmable, is the time to assert the LED output
and the LED OFF time, which is also programmable, is the time to negate the LED output.
Fig 5. Drop-down menu selections

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PCA9685 demonstration board OM13332
Fig 6. Device configuration screen for PWM0 to PWM3
Fig 7. Device configuration screen Control registers