You need a separate power supply for the panel. There is a connector for that
separate from the logic connector, typically a big one in the center of the
board. The board requires 5V (double check the polarity: what is printed
on the board is correct - I once got boards with supplied cables that had red
(suggesting +) and black (suggesting GND) reversed!). This power supply is
used to light the LEDs; plan for ~3.5 Ampere per 32x32 panel
A word about power
These displays suck a lot of current. At 5V, when all LEDs are on (full white), my 32x32 LED panel draws about 3.4A. For an outdoor panel that is very bright,
that can be twice as much.
I am running 2x 128x64 panels, an active-3 board and a pi zero W, and my power consumption at max brightness and full white is 3.5A for the whole lot. The panels probably consume ~2.5A
Looking at the git blame, seems hzeller wrote this 9 years ago - have modern panels gotten a lot better or something?
Am happy to submit a PR and tone this down a bit, whilst still making it clear that you need to take this into consideration.
Hi
Panel consumption depends not only on size, but also on the scan, driver type, and its settings. The typical maximum consumption for a modern panel is approximately 30-40 mA per LED, but this figure can be reduced by both driver settings and your software.
However, in any case, the typical maximum for two 128x64 panels is approximately 10-15 A. Your figure of 2.5 A clearly indicates that you are using no more than a quarter of the panel’s brightness.
Interesting. Not sure how it could be much brighter, at full brightness it’s clearly visible even in full direct light.
Would be curious as to what I can do to make it brighter and see if it does indeed use more power - all the options I see for the demo and utils only seem to make it dimmer (with the obvious exception of course of --led-brightness, but that’s at max anyway)
[Edit] actually, if I remove some of the options (eg –led-pwm-dither-bits=1 --led-pwm-lsb-nanoseconds=50) I can get it up to 4.8A, but still way short of 10-15A, and that’s still including ~1A of Pi usage.
Also not quite getting how come one 32x32 panel will draw 3.5A, but 16x that number of LEDs would only be 10-15A
Correct
On average, you can expect something around 25A for such panels. However, as I already said, it depends on the driver type and its settings.
Do you know a driver model on your matrix?
As far I see, the panel uses a FM6124 driver.
The datasheet for this chip is available; you can easily find it online. The very first page lists the maximum current for a single driver output: 32 mA when powered from 5 V.
Keep in mind that each color in an RGB LED powered by a separate driver, so this figure needs to be multiplied by three. This will give you about 100mA as the maximum current per pixel. You can estimate the value for a whole panel yourself, but I suspect the result will be way higher than what I just quoted.
Of course, in most cases, the pixel current in the matrix is ​​limited by hardware to prevent overheating and reduce consumption. However, if we’re talking about a warning in the documentation, it’s best to stick to the maximum.
Maximum power consumption(W/SQM): 880
x 0.0288 = 25.34W / 5v = 5.07A per panel
x2 panels = 10.14A
Average power consumption(W/SQM): 352
x 0.0288 = 10.14W / 5v = 2.03A per panel
x2 panels = 4.06A
Which seems more in line with what I am seeing, although to be fair, that appears to be the spec of the P2 / P4 variants of the panel (P2 is 128x64px, P4 is 64x32px), but seeing as the P2 is the same resolution as my P1.875 panel (Just a bit bigger), and the pixels will therefore be a bit bigger (Drawing more current?) I am guessing it is maybe even lower than those figures.
Unless his estimate of 32x32 panels drawing ~3.5A is for very large panels (P8?), In which case the way it is worded is misleading (Cos he says a 16x32 will draw less - but as per that manufacturer’s spec page I linked, it does not seem to be to do with pixel count, but more to do with size)
I see you don’t understand how the panel works. Do you know what the scan parameter means?
128 x 64 pixels never light up all at once. Your panel has a scan of 1/32, meaning only two lines of the entire panel light up at a time.
It depends.
As noted above, 7A per panel is a conservative figure for bright, light-colored images that completely fill the panel. A typical average value is around 2-3A per panel.
If you have low brightness and partial fill, such as single-color text with no background, you can get by with less than 1A per panel. For example, for testing purposes, I ran six 64x32 panels from a 2.5A PSU.
Surely that can’t be right.