CANdle U
ser’s Guide
www.ctr-electronics.com 1/17/2022
Cross The Road Electronics Page 20 1/17/2022
7. FAQ
7.1. Is there a way to tell if the device is present/powered?
To determine visually if the sensor is powered and functioning, check the built-in tri-color status LED, see
7.2. How do I control LEDs?
The CANdle and respective LEDs can be controlled either by the CAN bus or through an external controller generating a pixel
pulse train. For more information on the ways to control the CANdle, see
Additionally, the choice of how to control the LEDs will determine the wiring as explained in
7.3. How many LEDs can I drive from the CANdle?
There are two factors that determine how many LEDs a CANdle can control. Both are covered in sections below.
7.3.1. Software limiting LED count
There is
no
software
limit
when LEDs are controlled
via WS2812B-compliant pulse-train
(through CAN wires).
However,
firmware limits the maximum number of LEDs to 400
when controlled over
CAN bus
.
If this is adjusted in future firmware releases, this can be confirmed in Phoenix Tuner self-test.
7.3.2. Current Draw limiting LED count
The CANdle can supply up to I
MAX
of total current (combined return current from the 5V
OUT
and +V
OUT
rail).
Note the return current must be sunk through -V
OUT
.
Typically, this is sufficient for 300 GRB LEDs at max brightness.
Exceeding this may cause LEDs to appear dim or will cause CANdle to fault if current exceeds I
MAX
.
Limiting the brightness of the CANdle can be used to reduce the total current draw, thus allowing for more LEDs.
7.4. Is the CANdle an LED strip or LED controller?
The CANdle is both an LED strip and an LED controller. The first eight addressable LEDs are onboard and integrated. The first
extern LED added via the wire leads
is considered the “ninth” addressable LED.
This will be references as index
‘
8
’
in software.
7.5. Do I need to set the RGB type for the onboard eight LEDs?
No, the CANdle firmware already
compensates
for
the RGB color type
of the
onboard LEDs
.
You can select
any
external LED strip type that matches the available types in
7.6. Can I power my Raspberry Pi or Jetson Nano from the CANdle?
Yes, CANdle can power (non-inductive) loads that rated for 5V and no more than 6amps. Both products in their default
configuration require less than 6 amps, and so can be powered by the CANdle. If you are adding peripherals to a co-processor,
factor in the current consumption of that co-processor and determine if the total current budget is sufficient for a CANdle to
supply. A wiring diagram in
shows how to wire the CANdle to power a Raspberry Pi.
