onsemi STR-NCV7685-REAR-GEVK Evaluation Board User Manual
- June 8, 2024
- onsemi
Table of Contents
onsemi STR-NCV7685-REAR-GEVK Evaluation Board
Warnings
- Individual LED current can be changed in this system, however continuous operation of multiple LEDs with large current setting makes heat sink, PCB and devices extremely hot. Please operate under appropriate environmental conditions.
- LED board mounts 72 of high-efficient type power LEDs and there are very bright, even if LED current is small. Please avoid staring into the LED source without light guide.
Description
STR-NCV7685-REAR-GEVK is an evaluation board for car taillights application
with BLE function in automotive which driven by NCV7685 and controlled by
RSL10. This kit focuses multi-chips design to complete sophisticated patterns
and animations. Seventy-two LED nodes which are driven by six NCV7685 chips to
implement both pre-defined animations with configurable parameters and
customized pattern by controlling each single LED node.
To maximize the reusability of this evaluation board, the kit is divided into
three parts: LED board, LED driver and control board, RSL10 Linked board. Each
board can be reused separately for evaluation of similar applications. In
firmware, the drive APIs are divided into four levels: peripheral, chip, board
and customer application. User can directly include the chips and board APIs
in their own project and modify the customer APIs according to their own
applications, which can accelerate the developing stage. The kit has two kinds
of user interfaces: Strata GUI and general mobile BLE apps. Strata GUI has two
tabs: “Animation Demo” controls pre-defined animations; “Customized Test”
controls each single LED node to realize one pattern for verification. These
functions also can be done by BLE mobile App (LightBlue, BleScanner, etc.), or
customer can create specific app which is following the protocol with RSL10.
It is also an interior or exterior lighting reference design for ambient
lights to realize general sequential or high-end pixelated LEDs controlling
in-vehicle network. The skills of how to improve flash rate for animation,
floating address method of NCV7685 and other design tips can be found by this
evaluation board.
Features
- Strata GUI and general mobile BLE Apps
- Pre-defined Animations with configurable parameters
- Customized Pattern Design
- Reusability of each sub board
- Floating Address Method for Multiple NCV7685 Chips
- Hardware and Firmware Design skills for high flash rate of Animation
- On−Chip 150, 300, 600 and 1200 Hz PWM
- Logarithmic or Linear Independent PWM Dimming
- 2 MHz fixed−frequency low quiescent current buck controller with spread spectrum that operates up to 38 V
- Bluetooth® 5 Certified with LE 2M PHY Support
- Arm Cortex−M3 Processor and LPDSP32
Applications
- Rear Lighting of Automotive
- Ambient Lighting
- Celling Roof Lighting
- Automotive Synchronous Buck Power Supplier
Hardware Design
Architecture of the Kit
The kit is divided into three parts on the hardware: LED board, LED driver and
control board and RSL10 Linked board. So, Control board and Linked board can
be re-used in other lighting applications.
Figure 1: Architecture of the Rear Lighting Kit
LED board
Here are 72 high-efficient power LEDs, 20 in yellow and 52 in red, to show
specific pattern or amination. For each NCV7685 chip, here is one jumper in
their channel to test the “one off, all off” function.
Figure 2: Top of the LED Board
LED driver and control board
Supply the power for each part, 6 pieces of NCV7685 to drive power 72 LEDs,
RSL10 is the controller to communicate with both linked board and mobile BLE
apps, also send commands to NCV7685.
Figure 3: Top of the LED Driver and Control Board
Figure 4: Bottom of the LED Driver and Control Board
Function of key Parts
Below table lists the function of key part in the LED driver and control
board.
Table 1. Chip DESCRIPTION
| Chip Part | Description |
|---|---|
| NCV7685 | 12 Channels 60 mA LED Linear Current Driver I2C Controllable for |
Automotive
RSL10 SIP| System-in-Package, Bluetooth® 5 Certified
NCV891930| Low Quiescent Current 2 MHz Automotive Synchronous Buck Controller
NCV8170| Ultra‐Low IQ 150 mA CMOS LDO Regulator
NCS20091| Operational Amplifier, 5.5V Rail-to-Rail Input and Output, 350 kHz,
Single
NCS213| Current Sense Amplifier
NCP1406| Boost Converter
PCA9655| Remote 16-bit I/O Expander for I2C Bus with Interrupt
RSL10 Linked board
Interface to Strata system. Find more details in Onsemi webpage.
If the re-fresh rate of the LED board is acceptable, the control function of
LED driver board can be shift to RSL10 linked board to save cost. In this kit,
ADC functions for LED voltage and current sampling were shifted from control
board.
Figure 5: Strata Linked Board
Board Assembling
-
Following the below illustration to get assembling done.
Figure 6: Assembling of the Evaluation Kit -
As high-efficient type power LEDs are very bright, assemble light guide before power on the kit. Keep the height of gap is greater than 3 centimeters at least.
Figure 7: Assembling the Light Guide
Strata GUI
Setup Procedure of Strata GUI
- Go to www.onsemi.com/strata to download the latest version of Strata and follow the installation prompts.
- Launch and login to Strata with your registered account or guest.
Figure 8: Strata System Login
- Plug in 12V DC power and connect the USB Mini-B cable with the computer or laptop.
- Strata system will recognize the evaluation board automatically, then just click “Open Hardware” button on the right of the bar to demo and test.
Figure 9: Open Hardware Controls
Getting Help information of NCV7685 Rear Lighting Kit
Just click icon on top-right corner to show quick help in each panel. Each
part’s function will be detailed one by one. Here is an example: The “Right
Turn” button is highlighted, the others keep fading out, the popup window
shows the function and usage or parameters for “Right Turn” animation
.
Figure 10: Quick Help Example
“Animation Demo” Panel
“Animation Demo” page demonstrate seven kinds of animations and each one has
configurable parameters. Here is a brief for pre-defined animations.
“Welcome” and “Goodbye” animation: It demoes as “Leaving Home” or “Going Home”
in the automotive lighting.
“Left Turn ” and “Right Turn” animation: It shows left or right turn signal
function. Period and Cycle can be easily changed by drag the slider.
“Brake”: It shows brake light function in the car. Intensity (PWM duty) can be
changed by drag the slider. “Warning”: It shows hazard lights animation.
“Fading”: It shows breathing animation. It can be parsed as “In Charging” or
other meaning functions.
“Setting” button: It change NCV7685’s driving characters, e.g. PWM Frequency,
PWM drive mode is either logarithmic or linear. 
Figure 11: Animation Demo Panel
The below shows three state of icons:
“Idle”: Ivory and keep the original size.
“Ready”: When hovered in, the icon will be larger and in orange. After hovered
out, the icon resumes the original. “Active”: After clicked, the icon keeps
larger and in green.
Figure 12: Icon Status
“Customized Test” Panel
“Customized Test” page shows one frame, which contains seventy-two LEDs,
twenty in yellow and fifty-two in red, Each LED’s intensity can be set
individually to implement one pattern. The specific features of NCV7685 also
can be enable or disable in this page.
It is in grey when Les is off. Hovering in the specific LED, the intensity
slider popup, drag it and regulate to expected value. The slider is in yellow
when LED’s color is yellow, slider is in red when hovering in a read LED. the
slider will be fading out after hovering out the setting LED for three seconds
.
Figure 13: Customized Test Panel
BLE Mobile Apps Access
The NCV7685 Rear-Lighting Evaluation Kit also can access by general mobile
Apps. E.g. LightBlue, BleScanner… Here is an example using “Light Blue” App to
control the kit:
- Open LightBlue in the mobile.
- Find and choose Peripheral of “Strata_NVC7685”.
- Tap “BLE_TX_VALUE” character.
- Set command and parameter and send out data following the below protocol.
Figure 13: Using Light Blue App
The protocol between NCV7685 rear lighting kit with mobile app is very simple. Find the detail in the below table. For better security and reliability, users had better to work out the private protocols according to their application.
Table 2. Protocol of Demo Kit
Command| Header
(Byte 0–1)
| Length
(Byte 2)
| Code
(Byte 3)
| Parameters
(Byte 4 — 15)
| Examples
---|---|---|---|---|---
WELCOME| F1 F2| 2| F3| | f1 f2 02 f3 00
Demo welcome animation once.
LEFTTURN| F1 F2| 5| F4| | f1 f2 05 f4 00 06 d0 07
Demo left turn animation once; cycles = 6 times; period = 2000ms.
RIGHTTURN| F1 F2| 5| F5| | f1 f2 05 f5 01 06 d0 07
Repeat demo right turn animation; cycles = 6 times; period = 2000ms.
BRAKE| F1 F2| 2| F6| | f1 f2 02 f6 7f
Demo brake light to maximum value.
FADING| F1 F2| 5| F7| | f1 f2 05 f7 00 02 40 1f
Demo breathing animation once; cycles = 2 times; period =8000ms.
WARNING| F1 F2| 5| F8| | f1 f2 05 f8 01 02 e8 03
Repeat demo hazard light; cycles = 2 times; period =1000ms.
BYEBYE| F1 F2| 2| F9| | f1 f2 02 f9 01
Repeat demo goodbye animation.
LEDALL| F1 F2| 2| FA| | f1 f2 02 fa 01
All 72 LEDs turn on.
SETPWM| F1 F2| 5| FB| | f1 f2 05 fb 00 12 0c 01
autor disable, PWM freq=300Hz; Logarithmic mode
CHIP_1| F1 F2| 12| C1| | f1 f2 0d c1 61 62 63 64 65 66 67 68 69 6a 6b 6c
Update 12 LEDs of chip_1 values.
CHIP_2| F1 F2| 12| C2| | f1 f2 0d c2 71 72 73 74 75 76 77 78 79 7a 7b 7c
Update 12 LEDs of chip_2 values.
CHIP_3| F1 F2| 12| C3| | f1 f2 0d c3 71 72 73 74 75 76 77 78 79 7a 7b 7c
Update 12 LEDs of chip_3 values.
CHIP_4| F1 F2| 12| C4| | f1 f2 0d c4 71 72 73 74 75 76 77 78 79 7a 7b 7c
Update 12 LEDs of chip_4 values.
CHIP_5| F1 F2| 12| C4| | f1 f2 0d c5 71 72 73 74 75 76 77 78 79 7a 7b 7c
Update 12 LEDs of chip_5 values.
CHIP_6| F1 F2| 12| C6| | f1 f2 0d c6 71 72 73 74 75 76 77 78 79 7a 7b 7c
Update 12 LEDs of chip_6 values.
- Length byte only counts in parameters and command bytes as it’s simple protocol example.
Design Discussion
Floating Address for NCV7685
In general, the user is preferring to use fixed address in multiple NCV7685
application. It leads to add one more procedure to pre-programming each chips’
address in mass production stage. In addition, it is inconvenient for
maintenance in the aftermarket. In firmware of this evaluation board, it uses
floating address setting method, each time when power on the board, the
NCV7685 will be assigned an address which defined by customer, but not locked
into OTP registers. The user can realize this function by using either RSL10’s
GPIO or IO expender (PAC9655).
Improve Re-Flash Rate in Multiple NCV7685 chips design In multiple NCV7685
chips application, the re-flash rate can be improved both in firmware and
hardware.
In firmware, had better use short command to reduce the traffic in I2C bus to
realize the same function. For instance, use “ID_PWM” commands instead of
“ID_PWM_ALL” if all channel’s intensity is the same.
In hardware design, Utilize the maximum function of hardware features. For
example, we want to implement two patterns switched frequently, how about set
values in SAM1 and SAM2 firstly, then drive PWM on the CONF pin? NCV7685 is an
excellent chip in automotive lighting applications, it needs you to explore
more.
Operation Notes
-
As here are two I2C masters in the kit, if “LED and Control Board” is not initialized correctly, just press
“Reset” button to reset driver board. It shows “startup” animation after reset. -
In “Customized Test” Panel of Strata GUI, “Selected LED ON” command is divided into several JSON sentences and then sending to driver board. If the LED responded incorrectly in some situation, initialize “Customized Test” Page by switching to “Animation Demo” page and then switch back to “Customized Test” Page.
Schematic
Strata_NCV7685 Page
Power Page
LED_Driver Page
Controller Peripheral Page
To_Linked_Board Page
LED_Board_Left_Part Page
LED_Board_Right_Part Page
Top Overlayer of LED Board
Top Overlayer of Control Board
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References
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