Wiring the TM1814 LED strip

Refer to manufacturer instructions to identify the connections & connectors on your TM1814 LED strip.

Make the following connections:

• TM1814 power and GND to dedicated power supply according to manufacturer directions (e.g., 12VDC 20A)
• TM1814 GND to microcontroller GND
• TM1814 Data In to microcontroller A0 (GP26 on Pico / Pico 2)

Do not connect TM1814 power to microcontroller power, as this will damage the microcontroller.

LED Strip Organization

As mentioned above, TM1812 is designed to work with higher supply voltages. This is useful because it allows a strip to provide more total light with less total current. Of course, there's a hitch: The LED strip has to be designed such that it's appropriate to drive the LEDs with a higher voltage. The simplest way to do this is to place several LEDs in series. For instance, a 12V strip may have 3 RGBW LED packages controlled by a single TM1814 controller chip. The typical forward voltage of a white or blue LED is around 3V, and so when 3 are placed in series the typical forward voltage is 3V+3V+3V=9V. Add a few volts for operating margin, and the manufacturer assigns 12V as the nominal voltage of the strip.

In the photo below you can see that there's 1 TM1814 chip (the black rectangle) togther with 3 RGBW LEDs (white rectangles with circles). The strip manufacturer has marked the voltage (12V) and the data direction (data inputs at the left and outputs at the right)

LED strip power estimation

The per-chip maximum current is the chip supply current plus the LED current. The LED current can be up to 4*38mA = 152mA. Add 10mA per chip to account for the TM1814's own power usage, and multiply by the number of chips. That comes out to 16.2A for a 5-meter strip with 100 TM1814s and 300 RGBW LEDs. So a 12V 20A DC power supply is not unreasonable, and it may be helpful to connect GND and VCC at multiple points on the strip to reduce power supply sag under load. Wiring high current LED strips is out of scope for this guide, but never fear: there is a dedicated page within the NeoPixel Überguide just about how to power LED strips. This advice applies to TM1814, except that you have to observe the manufacturer's voltage rating, not the NeoPixel 5V advice.

If you set the current control registers to a lower value (see below) you can limit the overall strip current as well. For instance, at the lowest 6.5mA the maximum per chip current is probably 36mA, making the whole strip "only" 3.6A. However, you need to keep in mind that the current draw may be higher in self test mode.

In adafruit_tm1814, the default current is the lowest 6.5mA. The self test mode appears to use 12.5mA current.