Please help me identify the product 8x8 RGB matrix 4.7x4.7cm (32 pins) Model Number printed on the product as: TOM-1988BSP B-N/430. I have test the product it shows all Red,green,blue on each dot but i don't understand the the pin configuration for each color its quite confusing no datasheet or other information is available on the internet. I would like to drive them with 74HC595 and Arduino . I'll appreciate for all your help on this tiny thing working.
Rgb matrices are either common anode (8 anodes, 24 cathodes) or common cathode (24 anodes, 8 cathodes). Once you have established which, you just need to figure out which of the 32 pins are which! If you have already confirmed that each dot will light in red, green or blue, you already have that information, assuming you kept notes. You can also easily measure the forward voltage of each led colour. Then you have almost all the useful data you could have got from the data sheet.
595s are not a great chip for driving matrices. It's current limits are rather low. Also it has no pwm for colour mixing. It might be possible to do pwm in the code, but otherwise you will be limited to 7 colours.
Let us know of it is common anode of cathode, and we can suggest a circuit.
Color R+G+B (x 64)
Mounting Type Through Hole
Configuration 8x8 Matrix
Size 4.7 x 4.7 cm
Voltage Rating 2.1V
Current 25mA
I think the manufacture is Taiwan Oasis Technology Co Ltd Oasistek | LED Components Manufacturers services
They have other datasheets starting with TOM-1988xxx but not the one i have. I already contacted them to find out the datasheet so lets see if they have one.
I'm not that pro so I need little more help in the mean time on figuring out common anodes/ cathodes. Should i make table for each colors like for RED connecting all anode and cathode making all 64 glow and repeat for others. how many anode and cathodes should be there in case of RED to figure out that its common anode or cathode?
what will be the starting point i mean to figure out PIN 1. One more thing I need to connect some positive and grounds on both sides to glow all RED Leds. Should i post a sketch for all pins which glows like RED, Green and Blue separately to figure out the mystery puzzle actually I have 10 of these i'm using 595 to test only one of them if it works I buy some good TLC95xx s to drive them.
OK you just need to be methodical about it. Use a 5V supply but always use a series resistor eg. 330R between 5V and the matrix. Start by connecting matrix pin 1 to positive (via the resistor) and probe every other pin with a connection to ground. If nothing lights, move on to pin 2 and so on. If anything lights, the pin connected to positive must be an anode pin, and the pin connected to ground must be a cathode pin. The same pin cannot be both anode and cathode. Note the anode/cathode status of each pin on a diagram.
After digging internet for hours I was lucky to found out the exact datasheet for the Matrix. I did the trial to couple of pin with the help of datasheet and I got the positive result. So I guess the search is over and now to the second phase. Please take a view on the datasheet sketch and I have also marked pin outs on another image from the front facing towards me to avoid any confusion for starting point (Pin 1) full Datasheet is also attached. Now your valuable advise on circuit/schematic will be highly appreciated.
You need different parts.
MIC5891 to drive the anodes, one at a time.
3 x TPIC6B595 or TPIC6C595 to sink current current from the cathodes, one for each color with 24 current limit resistors.
Set up the column data ('595s), turn on a row (one output of 5891). Hold for 4mS, turn off anode, set up next column data, turn on next row, hold for 4mS, repeat for next 6 rows.
Will have up to 480mA flowing if all colors in a row are turned on at 20mA/LED.
CrossRoads:
MIC5891 to drive the anodes, one at a time.
3 x TPIC6B595 or TPIC6C595 to sink current current from the cathodes
Thanks for the tip about MIC5891, a useful chip!
Your suggestion would be for common anode matrix. For common cathode you would need 3 x MIC5891 and 1 x TPIC6x595. I don't think we have reliably established which the OP has.
The page from the data sheet that the OP posted has the words "Common Anode" in red next to a product code circled in red. But the product code does not exactly match the code printed on the side of the matrix. The diagram shown in the post is a common cathode display. We don't know if the OP added the red text. He is vague on that point in his post. I would interpret that vagueness as not knowing/understanding. Hence my question to the OP!
Also, these suggested parts would not support PWM dimming, like the tlc5940 mentioned by the OP. Your code suggestion would produce only 7 colours. With some clever coding, pwm could be achieved in software, using Bit Angle Modulation, for example.
But my main concern is that software multiplexing 10 x rgb matrix (especially if attempting pwm in software) or use of chips like tlc5940 are too complex for a beginner and attempting would likely result in failure and loss of confidence.
PaulRB may be i'm wrong as I am new to this. I have tested the single color RED to verify the pins so connected 8 anodes to 25,26,24,11,20,13,3,6 (positive) as per sketch and Cathodes/ground to pins shown in the sketch which lights up RED for all columns & ROWs to verify the datasheet. then I have connected all remaining ground pins (column) on both sides of the matrix to see what happens RED lights stayed there. if i remove any of the anode pins (ROW) the whole row of red turn off same happens to all other anode pins. What I remembered only one pin If i connect cathode to that all red leds turn off and if i connect anode to it nothing happens.
So as you say for anode matrix there should be 8 anodes. what do you think? is this matrix any different from other common RGB matrix other then the pin layout.
sorry not to mention before The red circle add by me as you mention for common anode matrix there will be 8 anodes?
CrossRoads different parts? is there any easy way ? all of stuff you have mentioned is above my head I'm still learning. How about ULN2803 to stabilize the current. I don't want intensive colors right now just want to test it out for three or more colors to see how it will works then i will go forward and go high tech how about schematic?
3 x 74hc595 to sink current from the 24 cathode pins. You will need to use quite high value series resistors so that you don't overload the 595s with too much current. Each 74hc595 can only sink 70mA in total. The matrix will not be very bright but OK for indoor use.
1 x 74hc595 to drive 8 x PNP transistors such as bc327 to source current to the anodes. You will need 8 x base resistors, around 1K ~ 4K7.
You can Daisy-chain all 4 shift registers so that you only need 3 Arduino pins. I would recommend using the Arduino's hardware SPI pins for this because you will need to send quite a lot of data per second for multiplexing, especially if you want to try colour mixing using bit angle modulation at a later time.
Alternatively you can use one less shift register and use 8 Arduino pins to drive the PNP transistors.
Excellent! thank you for your valuable instructions it will indeed help me getting started, but It would be more practical if you can provide any similar schematic or forward me to some other link/s for more knowledge on similar kind of RGB matrix. I have been watching some videos on youtube but I don't know how much functional it would be in my case. So your advise would be great.
I didn't watch the video in full, but the schematic shown at the start is what I was describing. However, I can't see any resistors on the transistor bases, which is a concern. Maybe they are FETs,I don't know.
victechpro:
2n5551 NPN Transistors are used in the video. But in your instructions you have mentioned PNP Transistors?
OK, now I understand why no base resistors were used. The npn transistors are used as "emitter followers". In that configuration, the current flowing into the transistor base is governed by the emitter current and the gain of the transistor, so no base resistor is necessary. There are disadvantages to this approach, but it seems to work OK in the video. The emitter voltage cannot exceed the base voltage, and will probably be around 0.7V lower. If the output voltage of the Arduino pin is a little less than 5V, then the emitter voltage could be not much more than 4V. But that is still 0.5~1V more than the blue leds need.
The voltage drop would be lower with PNP transistors, so the emitter voltage could be as high as 4.7V, at least 1.2V more than the blue leds need. You will need to limit the base current with resistors with this approach.
Yes, you can use the udn on the anode side and uln on the cathode side. That will also overcome the current limitations of the shift registers, so you can increase the led current up to the max to get more brightness. The problem you may have is the high voltage drop of those chips. The uln could drop between 0.7V and 1.5 V. I don't know about the udn but it could be similar. This may mean you need a supply voltage of 6V to 7.5V to get the blue leds to light.
PaulRB Thanks for everything I have learn a lot from this project. I have managed to build prototype successfully now I'm experimenting the coding part. Few things bothering me so I thought I could get advise from you. On first attempt I have build the circuit this way:
Anode side of the matrix connected through UDN2981A to Shift register.
I have put in (8+8+8) 24 Resistor to the cathode side with different value for each color to 3 shift registers.
All 4 Shift registers Daisy chained left with 4 wires.
Powered up the matrix with Arduino vcc/ground.
The brightens is acceptable. Now the problem is that the color mixing is not normal with UDN2981 for e.g if i bypass it I get the correct Yellow color otherwise its kind of RED/ Dark orange.
Any advise to fix it. Should i go on add ULN2803 on cathode side or should i redo the circuit putting 8
resistors on anode side and put ULN2803 on cathode side or you suggest any other alternate?
Thanks
P.S sorry not to mention as per calculation on 5v and current rating as per datasheet RED and GREEN i have put in 150 ohm resistors and 100 ohm for Blue
actually I have 10 of these i'm using 595 to test only one of them if it works I buy some good TLC95xx s to drive them.