Get2know: asynchronous & synchronous (SPI) protocols
DMX is very common for the control of dynamic luminaires and offers many advantages, but the differential protocol (D+,D-) must be converted e.g. into an asynchronous protocol for the control (dimming) of luminaires and pixels. This requires additional components and space inside the luminaire. Also, the number of channels is limited to 512. Especially for products like single-pixel controllable flex-tapes or chains this can be a disadvantage. Here it often makes sense to send directly the asynchronous or synchronous protocols directly to the converter/dimmer (chip). There are many chip types (RGB, RGBW, Monochrome) and chip manufacturers as well as those directly integrated in the LED or separately on the PCB.
This saves a lot of space, reduces hardware costs and allows a high number of channels to be controlled per line - resulting in new creative, higher resolution and highly flexible products. Due to the fact that the protocol is not differential (data+, data-) like DMX, the distance between the output device and the luminaire is reduced to about 3m. With special converters - e.g. the e:cue Pixel Range Extender - the corresponding asynchronous protocol can be reliably transported up to 300m. Here the controller first outputs the asynchronous protocol "differentially" (data+, data-, ground) and then converts it back again just before the LED product (D, ground).
Application areas and products
- There are many different asynchronous and synchronous (with additional clock) protocols, also called "SPI“.
- Around 2000 channels are possible on only one line.
- Space-saving due to the smaller number of components.
- With many chips, the intelligence is already located directly in the LED.
- Short distance between the controller and the first pixel - about 3m.
- With the e:cue Pixel Range Extender, asynchronous protocols can be transported up to 300 meters.
- High-resolution applications are thus easily possible.
Protocols in comparison
|Chip examples||-||TM1812, UCS2904, WS2813 ...||APA102|
|Max channels||512 (e:pix 2048)||Around 2000|
|Typical wiring||Data+, Data-, Ground||Data, Ground||Data, Ground, Clock|
|Max distance between controller and first pixel||150m||Approx. 3m, with Pixel Range Extender up to 300m||Approx. 3m|
|Typical application / products||Illumination with washer & liners, dot chains & low resolution tubes, strips & boards||Medial and artistic installations. Pixel tapes, tubes, LED chains, pixel mesh, boards. Products with high pixel density (resolution)|