Introduction to TM1637

The TM1637 is a versatile and easy-to-use display driver IC that simplifies the process of controlling 7-segment LED displays. This chip is widely used in various applications, such as digital clocks, timers, counters, and more. In this comprehensive tutorial, we will explore the features and capabilities of the TM1637 and learn how to integrate it into your projects.

What is the TM1637?

The TM1637 is a specialized chip designed to control 7-segment LED displays. It communicates with microcontrollers using a simple two-wire interface, making it easy to connect and control multiple digits. The chip handles all the necessary multiplexing and segment driving, allowing you to focus on the higher-level aspects of your project.

Key Features of the TM1637

• Supports up to 6 digits of 7-segment LED displays
• Two-wire interface for easy communication with microcontrollers
• Adjustable display brightness control
• Low power consumption
• Built-in key scan function for button input
• Compact package size (SOP-20)

Getting Started with TM1637

To begin working with the TM1637, you’ll need the following components:

• TM1637 display driver IC
• 7-segment LED display module (common cathode)
• Microcontroller (e.g., Arduino, Raspberry Pi)
• Breadboard and jumper wires
• Power supply (3.3V or 5V, depending on your microcontroller)

Connecting the TM1637 to a Microcontroller

The TM1637 communicates with a microcontroller using a two-wire interface, consisting of a clock line (CLK) and a data line (DIO). The connections are as follows:

Make sure to connect the LED display module to the TM1637 as per the module’s pinout. Typically, the pins are labeled as follows:

• CLK: Clock input
• DIO: Data input/output
• VCC: Positive power supply
• GND: Ground

Installing the TM1637 Library

To simplify the process of controlling the TM1637, you can use a library specifically designed for this purpose. For Arduino, one popular library is the “TM1637” library by Avishay Orpaz. To install the library:

1. Open the Arduino IDE.
2. Go to Sketch > Include Library > Manage Libraries.
3. Search for “TM1637” in the search bar.
4. Find the “TM1637” library by Avishay Orpaz and click “Install.”

With the library installed, you can now include it in your sketches and use its functions to control the TM1637 and the connected LED display.

Displaying Numbers and Text

One of the primary uses of the TM1637 is to display numbers and text on the connected 7-segment LED display. The library provides functions to make this task easy.

Displaying Numbers

To display a number on the LED display, you can use the showNumberDec() function provided by the library. Here’s an example:

#include <TM1637Display.h>

#define CLK 5
#define DIO 6

TM1637Display display(CLK, DIO);

void setup() {
  display.setBrightness(0x0f);
}

void loop() {
  int value = 1234;
  display.showNumberDec(value);
  delay(1000);
}

In this example, we create an instance of the TM1637Display class, specifying the pins connected to the CLK and DIO lines. In the setup() function, we set the display brightness using setBrightness(). The brightness value ranges from 0 (lowest) to 15 (highest).

In the loop() function, we use showNumberDec() to display the value of the value variable on the LED display. The function automatically handles the conversion of the number to separate digits and displays them on the connected segments.

Displaying Text

To display text on the LED display, you can use the setSegments() function. However, due to the limited number of segments on a 7-Segment Display, not all characters can be displayed accurately. Here’s an example of displaying text:

#include <TM1637Display.h>

#define CLK 5
#define DIO 6

TM1637Display display(CLK, DIO);

void setup() {
  display.setBrightness(0x0f);
}

void loop() {
  uint8_t segments[] = {
    SEG_A | SEG_B | SEG_C | SEG_D | SEG_E | SEG_F,  // H
    SEG_A | SEG_D | SEG_E | SEG_F | SEG_G,          // E
    SEG_D | SEG_E | SEG_F | SEG_G,                  // L
    SEG_D | SEG_E | SEG_F | SEG_G                   // L
  };

  display.setSegments(segments);
  delay(1000);
}

In this example, we define an array called segments that contains the segment patterns for each character we want to display. The segment constants (e.g., SEG_A, SEG_B, etc.) represent the individual segments of a digit. By combining these constants using the bitwise OR operator (|), we can create patterns for specific characters.

The setSegments() function takes an array of segment patterns and displays them on the LED display. In this case, we’re displaying the characters “H,” “E,” “L,” and “L.”

Controlling Display Brightness

The TM1637 allows you to control the brightness of the connected LED display. You can adjust the brightness using the setBrightness() function, as shown in the previous examples. The brightness value ranges from 0 (lowest) to 15 (highest).

Here’s an example that demonstrates changing the display brightness:

#include <TM1637Display.h>

#define CLK 5
#define DIO 6

TM1637Display display(CLK, DIO);

void setup() {
  display.setBrightness(0x0f);
}

void loop() {
  for (int brightness = 0; brightness <= 15; brightness++) {
    display.setBrightness(brightness);
    display.showNumberDec(1234);
    delay(500);
  }
}

In this example, we use a for loop to iterate through brightness values from 0 to 15. Inside the loop, we set the display brightness using setBrightness(), display a number using showNumberDec(), and introduce a delay of 500 milliseconds. This creates an effect where the display gradually becomes brighter and then resets to the lowest brightness level.

Using the Key Scan Function

The TM1637 has a built-in key scan function that allows you to detect button presses connected to the chip. This feature enables you to create interactive projects that respond to user input.

To use the key scan function, you need to connect buttons to the TM1637 chip according to the following pinout:

• K1: Button 1
• K2: Button 2

Here’s an example that demonstrates reading button presses using the key scan function:

#include <TM1637Display.h>

#define CLK 5
#define DIO 6

TM1637Display display(CLK, DIO);

void setup() {
  display.setBrightness(0x0f);
}

void loop() {
  uint8_t buttons = display.getButtons();

  if (buttons & 0x01) {
    display.showNumberDec(1);
  } else if (buttons & 0x02) {
    display.showNumberDec(2);
  } else {
    display.clear();
  }

  delay(100);
}

In this example, we use the getButtons() function to read the state of the buttons connected to the TM1637. The function returns a byte value, where each bit represents the state of a button (0 for released, 1 for pressed).

We then use bitwise AND operations (&) to check if specific buttons are pressed. If button 1 is pressed (connected to K1), we display the number “1” on the LED display. If button 2 is pressed (connected to K2), we display the number “2”. If no buttons are pressed, we clear the display using the clear() function.

The delay(100) statement introduces a small delay between each iteration of the loop to debounce the button presses.

Advanced Techniques

Creating Custom Segment Patterns

While the TM1637 library provides functions for displaying numbers and basic characters, you may want to create custom segment patterns for special characters or symbols. To do this, you can define your own segment patterns using the segment constants.

Here’s an example that demonstrates creating a custom segment pattern:

#include <TM1637Display.h>

#define CLK 5
#define DIO 6

TM1637Display display(CLK, DIO);

void setup() {
  display.setBrightness(0x0f);
}

void loop() {
  uint8_t customPattern[] = {
    SEG_B | SEG_C | SEG_E | SEG_F | SEG_G,  // °
    SEG_A | SEG_B | SEG_F | SEG_G,          // C
  };

  display.setSegments(customPattern);
  delay(1000);
}

In this example, we define a custom segment pattern for the degree symbol (°) and the letter “C”. We combine the segment constants using the bitwise OR operator (|) to create the desired patterns.

We then use the setSegments() function to display the custom segment patterns on the LED display.

Scrolling Text

If you want to display text that is longer than the number of digits available on your LED display, you can implement a scrolling effect. This involves shifting the characters across the display over time.

Here’s an example that demonstrates scrolling text:

#include <TM1637Display.h>

#define CLK 5
#define DIO 6

TM1637Display display(CLK, DIO);

const char* scrollText = "Hello, World!";
const int scrollDelay = 300;

void setup() {
  display.setBrightness(0x0f);
}

void loop() {
  for (int i = 0; i < strlen(scrollText) - 3; i++) {
    display.showString(scrollText + i);
    delay(scrollDelay);
  }
}

In this example, we define a string called scrollText that contains the text we want to scroll. We also define a delay value (scrollDelay) that determines the speed of the scrolling effect.

Inside the loop() function, we use a for loop to iterate through the characters of the scrollText. We start from index 0 and continue until we reach the end of the string minus 3 (since we can display up to 4 characters at a time).

Inside the loop, we use the showString() function to display a substring of scrollText starting from the current index (i). We then introduce a delay using delay(scrollDelay) to control the scrolling speed.

This creates an effect where the text appears to scroll from right to left across the LED display.

Frequently Asked Questions (FAQ)

1. Can I connect multiple TM1637 displays to a single microcontroller?
   Yes, you can connect multiple TM1637 displays to a single microcontroller. Each display requires its own set of CLK and DIO pins. Make sure to create separate instances of the TM1637Display class for each display and specify the appropriate pin numbers.

2. What is the maximum number of digits supported by the TM1637?
   The TM1637 can support up to 6 digits of 7-segment LED displays. However, the actual number of digits you can control depends on the specific LED display module you are using.

3. Can I control individual segments of a digit?
   Yes, you can control individual segments of a digit using the setSegments() function and the segment constants (e.g., SEG_A, SEG_B, etc.). By combining these constants with bitwise operations, you can create custom patterns for each digit.

4. How do I change the display brightness?
   You can change the display brightness using the setBrightness() function. The brightness value ranges from 0 (lowest) to 15 (highest). Call this function before displaying any content on the LED display.

5. Can I use the TM1637 with other microcontrollers besides Arduino?
   Yes, you can use the TM1637 with other microcontrollers that support the two-wire interface protocol. However, you may need to find or write a library specific to your microcontroller platform to communicate with the TM1637 chip.

Conclusion

In this comprehensive tutorial, we explored the TM1637 display driver IC and learned how to use it with 7-segment LED displays. We covered the basics of connecting the TM1637 to a microcontroller, installing the necessary library, and displaying numbers and text on the LED display.

We also delved into more advanced techniques, such as controlling display brightness, using the key scan function for button input, creating custom segment patterns, and implementing scrolling text effects.

By understanding the capabilities and functionalities of the TM1637, you can create a wide range of projects that involve displaying information on LED displays. Whether you’re building a digital clock, a timer, a counter, or any other application that requires numerical or textual output, the TM1637 provides a simple and efficient solution.

Remember to refer to the TM1637 library documentation for more detailed information on the available functions and their usage. Experiment with different display configurations, custom patterns, and interactive elements to create engaging and informative projects.

Happy coding and enjoy working with the TM1637 display driver IC!