The Embrava Blynclight family of products is diverse but the physical articles I've tested all seem to share a base software implementation. Specifically, I've personally tested the BLYNCUSB30 (Blynclight), BLYNCUSB40S (Blynclight Plus) models and the Blynclight Mini. Also of note, Plantronics briefly sold a rebranded BlyncLight Plus as the Plantronics Status Indicator. The only difference between the two devices that I could determine was the vendor identifier, documented below.
These two lights are very similar and consist of a square pedestal topped by a cubical transluscent diffuser. The pedestal houses the PCB board of the device and features five LEDs exposed on the top. The LEDs are arranged in a "checkerboard" configuration and are not individually addressable. There is a female USB-mini connector which allows connecting the device to a host with any in-spec length cable.
The Blynclight Plus appears to have a downward firing speaker, however covering the bottom grill does not seem to attenuate how loud the device is.
The devices are roughly 2 inches tall, and 1.5 inches on a side.
- Vendor/Product ID values:
- 0x2c0d, 0x0001: Blynclight
- 0x2c0d, 0x000a: Blynclight Mini
- 0x2c0d, 0x000c: Blynclight Plus
- 0x0e53, 0x2517: Blynclight Mini
- 0x0e53, 0x2517: Blynclight
- 0x047f, 0xd005 (Plantronics)
- I/O Interface: HID
write - Command Length: 9-bytes
The Embrava Blynclight is a USB HID accessible device whose attributes are controlled by writing a nine (9) byte packet to the device.
The following is a C language structure type definition using bit fields to illustrate the structure of the 9-byte packet. Examples for configuring the device for different functions will be given in C, however they should be very accessible regardless of what language the reader may be familiar with.
A structure bit field in C is declared as a member of a struct,
usually an unsigned int, followed by a width specifier. The
header field specified below is an 8-bit (1-byte) field, while
the off field is a single bit field. Fields prefixed with pad
are unused and defined to maintain the correct offsets within the
structure for fields that follow.
typedef struct {
unsigned int header: 8; /* 64:71 Constant: 0x00 */
unsigned int red: 8; /* 56:63 Red color value [0-255] */
unsigned int blue: 8; /* 48:55 Blue color value [0-255] */
unsigned int green: 8; /* 40:47 Green color value [0-255] */
unsigned int off: 1; /* 39:39 Set is off, zero is on */
unsigned int dim: 1; /* 38:38 Set is dim, zero is bright */
unsigned int flash: 1; /* 37:37 Set is flash on/off, zero is steady */
unsigned int speed: 3; /* 34:36 Flash speed mask: 1<<0, 1<<1, 1<<2 */
unsigned int pad0: 2; /* 32:33 Unused bits */
unsigned int music: 4; /* 28:31 Stored music index: [0-15] */
unsigned int play: 1; /* 27:27 Set play selected music, zero is stop */
unsigned int repeat: 1; /* 26:26 Set repeats playing music, zero is once */
unsigned int pad1: 2; /* 24:25 Unused bits */
unsigned int volume: 4; /* 20:23 Volume of music: [0-15] */
unsigned int mute: 1; /* 19:19 Set is mute, zero is unmute */
unsigned int pad2: 3; /* 16:18 unused bits */
unsigned int footer: 16; /* 00:15 Constant: 0xFF22 */
} blynclight_ctrl_t;The device requires the inital byte of the control word to be zero and
the final two bytes of the word be set to 0xFF22. The device is
effectively write-only as I have not been able to get the device to
return anything via the read or get_feature_report interfaces
(beyond nulls).
Turning the light on requires the user to supply a control word with
off de-asserted (zeroed) and one or more non-zero red, blue or green
values. Please note that this device does not follow the RGB
convention of color ordering; the order of green and blue is swapped,
RBG. This is only an issue if you are updating all three fields
by writing a 24-bit quantity to the red value offset.
Example: Activate Light with Purple Color.
blynclight_ctrl_t cword;
cword.red = 0xff;
cword.blue = 0xff;
cword.green = 0x00;
cword.off = 0;
/* write control word to device */Please note that clearing the off field is not enough to provoke a
visible effect form the device; a color must also be given otherwise
the light is "on" with a black color. This can be frustrating.
Turning the light off only requires setting the off field and writing
the control word to the device.
The light can be put into a dim state by asserting the dim bit, resuming
"bright" operation when dim is cleared.
The light can be made to flash on and off, alternating between the
specified RGB value and off. The flash speed is controlled by the
3-bit speed field which is used to specify three speeds: slow, medium
and fast.
Example: Configuring Flash Mode
blynclight_ctl_t cword;
cword.flash = 1
cword.speed = 1 << 0; /* slow speed */
cword.speed = 1 << 1; /* medium speed */
cword.speed = 1 << 2; /* fast speed */When flash is set and speed is set to any value other than (1, 2, 4),
the light will respond by strobing on and off very quickly.
Some models of Blynclight provide the ability to trigger playback of tones stored in the firmware of the device, e.g. Blynclight Plus and others.
Playback of stored tones is controlled by the play, repeat,
music, volume and mute fields. The 4-bit music field selects
which stored sound to play. The repeat field toggles whether the
sound is played one time or repeated indefinitely. The 4-bit volume
field specifies the volume the sound is played at where zero is silent
and 0xF is the maximum. The mute bit controls whether the volume
setting is respected or clamped to zero at the device. Finally, the
play bit initiates playback of the selected sound with the specified
volume and repeat value.
Practically, I could not distinguish any difference in loudness for volume values between 1 and 0xf.
Example: Playing the First Sound One Time
blynclight_ctl_t cword;
cword.play = 1
cword.music = 1
cword.volume = 1
cword.mute = 0
cword.repeat = 0The Embrava Blynclight is simple, robust device. The only edge case
behavior I've encountered is the strobe effect achieved when flash
is set and speed is [0,3,5,7]. The light is very responsive and I
have not been able to induce an error state in the light that
required "rebooting" (unplug/plug) the light to recover normal
function.
I cannot say for sure that the tone identified by music value 0 on the BlyncLight Plus is intended, it is very harsh. It's possible that it is an unaccounted for state.
Oddly, it appears the latency in writes to the BlyncLight and BlyncLight Plus are different. If both lights are set to update free running in their own threads, the behavior of the lights will rapidly drift. For instance, if both lights are being driven with rainbow spectrum colors from seperate threads, they will rapidly drift apart with respect to the color being displayed. It may be a thread scheduling issue, but I strongly suspect the write latency as the source of the drift.
I used WireShark to snoop the USB bus while using Embrava's software to decode the BlyncLight's command format. Embrava provides some support for third-party developers in the form of SDKs (Windows, Mac and Linux) however the developer forum is not actively engaged by Embrava engineers and the SDKs are not updated regularly.
- Read current state
- Individual control of the five LEDs