About the light intensity of 32x32 RGB LED Matrix Panel 607

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nanaserena
 
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About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by nanaserena »

Last week I bought a 32x32 RGB LED Matrix Panel (https://www.adafruit.com/product/607) ,and It is controlled from adurino mega2560 .

and I tried the code like these to light up just 1 led with a 5v, 4000mA power:

****************************************************
// colorwheel demo for Adafruit RGBmatrixPanel library.
// Renders a nice circle of hues on our 32x32 RGB LED matrix
// http://www.adafruit.com/products/607
// 32x32 MATRICES DO NOT WORK WITH ARDUINO UNO or METRO 328.

// Written by Limor Fried/Ladyada & Phil Burgess/PaintYourDragon
// for Adafruit Industries.
// BSD license, all text above must be included in any redistribution.

#include <RGBmatrixPanel.h>

// Most of the signal pins are configurable, but the CLK pin has some
// special constraints. On 8-bit AVR boards it must be on PORTB...
// Pin 11 works on the Arduino Mega. On 32-bit SAMD boards it must be
// on the same PORT as the RGB data pins (D2-D7)...
// Pin 8 works on the Adafruit Metro M0 or Arduino Zero,
// Pin A4 works on the Adafruit Metro M4 (if using the Adafruit RGB
// Matrix Shield, cut trace between CLK pads and run a wire to A4).

#define CLK 11 // USE THIS ON ADAFRUIT METRO M0, etc.
//#define CLK A4 // USE THIS ON METRO M4 (not M0)
//#define CLK 11 // USE THIS ON ARDUINO MEGA
#define OE 9
#define LAT 10
#define A A0
#define B A1
#define C A2
#define D A3

RGBmatrixPanel matrix(A, B, C, D, CLK, LAT, OE, false);

void setup() {
int x, y, hue;
float dx, dy, d;
uint8_t sat, val;
uint16_t c;

matrix.begin();


c = matrix.ColorHSV(1535, 255, 255, true);

matrix.drawPixel(12, 11, c);
}



void loop() {
// Do nothing -- image doesn't change
}
****************************************************

But I found that under 5V voltage, this only used 0.045A current.
The light intensity was too weak with this code. I want to ask how to light only one led and make it the brightest, or what is the maximum light power of just 1 led.


Product: 32x32 RGB LED Matrix Panel - 4mm Pitch
ID: 607
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adafruit_support_bill
 
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Re: About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by adafruit_support_bill »

You will have more direct control over the intensity using the Color() function instead of ColorHSV(). ColorHSV attempts to interpolate hues on the color wheel by modulating the relative intensity of the R, G and B channels. And, since these panels do not have hardware PWM, fine-grained modulation is not possible.

With the Color() function, you can directly specify the duty cycle of each channel. For full intensity red use Color(255,0,0).

These are small LEDs. At most you can expect them to draw about 20mA per channel (plus some baseline current draw for the panel circuitry).

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nanaserena
 
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Re: About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by nanaserena »

1
Last edited by nanaserena on Tue Nov 22, 2022 11:07 pm, edited 1 time in total.

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nanaserena
 
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Re: About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by nanaserena »

adafruit_support_bill wrote: Tue Nov 22, 2022 9:08 am You will have more direct control over the intensity using the Color() function instead of ColorHSV(). ColorHSV attempts to interpolate hues on the color wheel by modulating the relative intensity of the R, G and B channels. And, since these panels do not have hardware PWM, fine-grained modulation is not possible.

With the Color() function, you can directly specify the duty cycle of each channel. For full intensity red use Color(255,0,0).

These are small LEDs. At most you can expect them to draw about 20mA per channel (plus some baseline current draw for the panel circuitry).
Hello,I tried the code “matrix.Color888(255, 0, 0)” to light up a LED but the light intensity was still too weak,We used an optical power meter to measure,the luminous power was only 1.2 uw.Theoretically, light power cannot be so small,but the external power supply shows that the current is normal.I don't understand what went wrong.
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Re: About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by adafruit_support_bill »

There is not enough information in the data presented to draw any conclusions.

To determine the current going to the LED, you need to subtract out the current that is driving the panel itself.
Measure the panel current draw with nothing illuminated. That will give you the base level current draw for the logic circuitry on the panel. The difference between that and the current draw with the LED illuminated will be the current going to the LED.

And it is not clear how you are attempting to measure the power output. What type of sensor are you using and how is it positioned relative to the diode under test?

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nanaserena
 
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Re: About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by nanaserena »

adafruit_support_bill wrote: Wed Nov 23, 2022 7:25 am There is not enough information in the data presented to draw any conclusions.

To determine the current going to the LED, you need to subtract out the current that is driving the panel itself.
Measure the panel current draw with nothing illuminated. That will give you the base level current draw for the logic circuitry on the panel. The difference between that and the current draw with the LED illuminated will be the current going to the LED.

And it is not clear how you are attempting to measure the power output. What type of sensor are you using and how is it positioned relative to the diode under test?
Thank you for your reply,we measure the panel current draw with nothing illuminated and then measure the panel current draw with just 1 LED on, the current difference between them is far less than 1mA.For this reason, we also replaced the resistors such as RB1 and RG1 to a smaller one.But the current going to the LED was still just close to 2mA,far less than 20mA.Therefore, we believe that the insufficient brightness of the LED is caused by the low current flowing to the LED.I want to ask how to increase the current flowing to a single LED, and continue to replace the input resistance?
The picture shows the change of output current before and after lighting an LED and the resistors we replaced.
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Re: About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by adafruit_support_bill »

We do not have the manufacturer's design documents for the display circuitry on these matrices. But the individual LEDs in the display are most likely multiplexed. So the expected average current draw will be a fraction of the peak.

Multiplexing is pretty much standard practice for a matrix like that. If all the LEDs were driven with constant current, you would need about 60A to drive it to full intensity on all pixels. A 60 Amp power supply would be impractical. And the display would likely require active cooling to survive.

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nanaserena
 
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Re: About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by nanaserena »

adafruit_support_bill wrote: Fri Nov 25, 2022 7:29 am We do not have the manufacturer's design documents for the display circuitry on these matrices. But the individual LEDs in the display are most likely multiplexed. So the expected average current draw will be a fraction of the peak.

Multiplexing is pretty much standard practice for a matrix like that. If all the LEDs were driven with constant current, you would need about 60A to drive it to full intensity on all pixels. A 60 Amp power supply would be impractical. And the display would likely require active cooling to survive.
Thank you for your reply. We guarantee that only one led is on at the same time. Our goal is to light just one led at a time and make it the brightest, that is, the current flowing through this led reaches 20mA. But we find that the current flowing through this led is far less than 20mA. Is this normal?

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Re: About the light intensity of 32x32 RGB LED Matrix Panel 607

Post by adafruit_support_bill »

As I explained, the LEDs in the display are most likely multiplexed. This is a common feature of LED matrices since it greatly simplifies the circuitry.

Much like a CRT, only one row is displayed at a time. So the average current draw for a single LED is going to be much less than the peak current draw.

See the section on "Pixel-Oriented Displays" in this link:

https://en.wikipedia.org/wiki/Multiplexed_display

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