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Tlc5947Voting resources, early voting, and poll worker information - VOTE. Adafruit is open and shipping. Please be positive and constructive with your questions and comments. I'd like to get three of them so I can connect one LED strip to each pin on the three driver boards. The tutorial is for the Arduino but I'm assuming this board will work with the Pi as well? I have a few questions. Do the boards need to be connected to certain pins on the Pi? Is there a Python library available for the Pi? In the description of the product, it says "We use a 3. Does that mean each pin of the driver board provides 15mA? Will the LED strips be dim? I've never used LED strips before Will these boards handled all of the current for these LED strips? It's a constant-current driver, so yes, you only get 15mA per channel. For large LED strips, you need mosfets to control the power, and a PWM generator that can deliver the kind of signals mosfets can use. It's chainable, and you can have up to 62 of them on the same I2C bus. Will the board be able to power LEDs using 12 volts? What is the max mA for each of the 16 pins? Do you have any chips without PWM? The mosfets will control the LED strips, and those can have just about any voltage. Most analog LED strips are arranged to run at 12v or 24v, and most mosfets are good for voltages up to about 40v. Those work well with the PCA If not, that'll save me 16 wires per PCA and a lot of soldering! You do not have the required permissions to view the files attached to this post. You do need a GND connection between the PCA breakout and the board that holds the mosfets, but you only need one. As long as the mosfets have that reference, you don't need one connection per channel. As long as all your mosfets have a connection to that GND rail, they'll work. I didn't think about compensating for the fact my strips were 24V instead of 12V on the schema. Do you also have a PWM circuit for driving 24V LED strips now it dims, but only a little bit when going from to 0 or is there another way I could drive this strip from my raspberry?
I tested this using the Adafruit library and it works as expected. So far so good. I now want to replicate the functionality with native C code using Studio 7. The Arduino code allows you to use any of the digital ports to send the serial data to the TLC. Having read a number of posts on this subject in the forums, it would appear I need to bitbang the ports. Is this correct? If so, the code I've looked at seems fairly complex, yet the Arduino lib just seems to fire out the data to the TLC via digital writes. Would it be better to redesign the boards and make use of native SPI hate to ditch the boards though or is it a fairly simple thing to do Arduino code was adequate speed wise? No, you do not need to bit bang the ports. I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie. Dead people don't sue! A prediction of the expected traffic load? Speak sweetly. Please Read: Code-of-Conduct. For the original poster, nikm, if done smartly, bit-bang can be almost as good has hardware interface at standard I2C speeds. A library with very high reputation is the Fleury I2C master code. I was getting a little excited there for a mobut yes sadly Jim is correct it's SPI. There are also a fair number of libraries around. Some even have software implementations. I looked at the code I have and I don't think it will be of much use for you as it uses the SPI engine rather than bit-bang. I also noticed that there is no commenting in it which will make life difficult to understand as well. Surprised as a fellow freak came up with this snippet for me a few years ago. Even in assembly maybe 25 instructions. Do you feel you need some sort of library to toggle a few pins? Also, since most SPI chips are static, there is no need to generate all the bits at once, or pre-pack them together when bit-banging. When in the dark remember-the future looks brighter than ever. I look forward to being able to predict the future! I've had a good search over the last 36 hours, most code snippets are based on hardware but I have enough to go on now. I have 3 TLC's daisy chained to give me 64 outputs. I've done tests with the Adafruit library and performance is acceptable. Perhaps in the next iteration of the board I'll split them up using 2 more pins for SS which will make it more efficient. I'll also wire up the SPI pins to make things easier. The code examples I looked at weren't very obvious in their workings with regards to SPI or at least they weren't to me. I converted in to 'plain C'. I don't see what the license issue is - have you read the various licenses for Atmel Studio 7? The gcc libraries are GPL and you don't seem to have issue with that. Kartman wrote: The gcc libraries are GPL.
Arduino tlc5940Voting resources, early voting, and poll worker information - VOTE. Adafruit is open and shipping. Please be positive and constructive with your questions and comments. The plan was to control multiple RGBL analog strips via external power since the strips are long enough to need the additional current by using the PWM pins on the to interact with mosfets. While researching how to use the PWM pins like normal arduino PWM pins, I learned that whatever is connected to the will flicker whenever you write to it or after x milliseconds or something, it doesn't really matter, the point is that LED's will visibly flicker under normal use. I reread the product page on the adafruit site and still didn't see anything warning about the flickering problem, although that would probably bite into sales so I'm not surprised. So now I'm here and need to reevaluate the project. This lead to a few questions. How do I make it so that LED's won't flicker when using the ? What would I need to buy to make the switch mosfets like the PWM pins on the arduino? Preferably something straightforward like a shield that you just plug in, load a library and you've got more PWM pins to work with. You do not have the required permissions to view the files attached to this post. I think I'm pretty close to the circuit above. Technically the resistors aren't 10k and that's an NPN transistor but I'll pretend it's the right hardware for the sake of demonstrating. The base -middle pin- of the transistor has a 10k resistor going to a white lead that goes back to a PWM pin on the board. The collector -left pin- of the transistor has a 10k resistor going to ground and a red lead connecting to the gate of the mosfet. The mosfet has a blue lead going from the drain -middle pin- to the blue lead of the led strip. The source -left pin- of the mosfet has a black lead going to ground. I think that's right? Then the collector of the transistor is connected to both the gate of the mosfet and the common ground so it should switch the mosfet. Maybe I'm supposed to use a different V source going to the transistor's emitter? Any common PNP will be able to handle voltages up to about 40v. Let me see if I'm understanding this diagram right. The emitter pin on the transistor, the one with the arrow on the diagram, connects directly to 12V. And finally the collector has two connections, one going directly to the mosfet gate and the other going to ground with a 10k resistor. I figure the example code will occasionally turn pin 0 on the board on and off, but it's not happening. I'm thinking I misinterpreted what's going on at the collector pin on the transistor. Plugging it back in usually turns the LED back on. Not sure if that's important or indicative of anything. And it's got some flickering issues when fading. It's a little tricky to see but here's a video. On camera, the flickering shows up in more of a weird distortion and waves around the LED strips. To the eye it's definitely visible. Maybe the tlc needs a capacitor on it? Or maybe I should look into that trick of shorting the OE and CLK pins together that seems to have worked for others for reasons that aren't clear? It is driving a PNP transistor which is driving a mosfet and both take time to switch.
Tlc5940ntIt is only available in a surface mount package that TI calls "power pad". The TLC operates by having a host microcontroller shift bits into it. So every "update", the host microcontroller should shift bits or 36 bytes. Here is example code. Arduino with a ATmega controller. Note that Arduino's digitalWrite commands are not used, as they were found to take too much time. With the true c commands, the port registers are directly changed. When you use the Arduino digitalWrite commands, it goes through other things in the background. What does constant current mean? It means that the TLC can limit the current coming out of each output. The advantage of constant current is that I can connect LEDs directly to the output without any resistors. If you use a chip without constant current, you will have to put resistors of the appropriate value depending on your VCC voltage. Increasing the resistor value should lower the temperatures. You can download the Eagle schematic and board files here. Design by XHTML 1. About Contact.