The goal of this tutorial is to get you familiar with the Serial 7-Segment Display. This tutorial also covers the 7-Segment Shield.
If you have the 7-Segment Shield, we recommend going to its tab first and beginning your journey there. The board is very easy to use since you can just plug it straight into an Arduino Uno compatible board and you can use the same exact code examples as the Serial 7-Segment Display which are covered in this tutorial.
Aside from the display itself, you'll need an Arduino or one of its variants to send the serial data. You'll also need some way to connect between the display and Arduino. You could use a combination of male headers and breadboard. Or, you could just go with a few pieces of wire. In order to make use of the Serial 7-Segment Display, you'll need to solder to at least a few of its pins.
That means you'll need at least a basic soldering iron as well as solder. Check out our how to solder tutorial for help, if this is you first time soldering. Before reading about how to hook up the Serial 7-Segment Display, it'll help to be familiar with some of these concepts. Consider reading through these tutorials before continuing on:. This page covers the hardware end of the Serial 7-Segment Display let's shorten that to S7S from here on. Everything from the pin-out, to powering the display is covered here.
To begin, we should mention, the display comes in an assortment of color options: red , green , blue , yellow , and white. The S7S has a lot of pins broken out in just about every-which direction. You'll actually only need to connect to about of those pins. Most of the pins can be broken down into categories based on the interface for which they're used.
This image should do most of the explaining:. It'll be your choice to decide which of the three serial interfaces you'd like to use to connect to the display. Using a basic serial input, you'll only need to connect to the RX pin. I 2 C requires two pins, and SPI requires three. Regardless of which interface you choose to send data, there are two pins to which you must connect: the power pins!
To get a S7S up and running, you'll first need to figure out how to power the thing. The S7S can be powered from a variety of voltage supplies. It can operate at anywhere from 3.
Keep in mind that the supply voltage will affect how bright the display is -- higher voltages increasing the maximum brightness.
The display's supply voltage is unregulated. So don't give it any crazy-high voltages, anything over 6. Be nice to your S7S! If you're using an Arduino, you could power the S7S off either the 5V or 3. Don't forget to connect ground GND as well. The "Serial" in the Serial 7-Segment Displays is something of a generalization. Each of these interfaces offer their own benefits and disadvantages.
A big difference between each of the communication protocols is the number of pins each requires. They also each add their own level of complexity on the firmware end though, with Arduino, libraries really simplify the task.
If you've played around with Arduino, you've probably used the hardware UART to relay information back to your computer via the Serial Monitor. Or set up a software serial port using the SoftwareSerial library. This form of serial communication is asynchronous , meaning the data is transmitted without any help from a parallel clock signal. This makes our job easier and harder. Easier in that we only need one wire RX to communicate with the display.
Harder in that extra attention needs to be paid to making sure timing between bits is exact. The S7S supports a range of very common baud rates , and defaults to everyone's favorite - The baud rate can be adjusted, if you please, but the display will only allow for 8 data-bits , no parity , and 1 stop bit 8N1. SPI is a synchronous serial communication method. It's kind of like taking the UART method above and adding a clock signal.
This way we don't have to worry about what speed we send data as long as it's not too fast , but we do require the use of two more pins. A couple caveat's on this serial method: the maximum clock speed for the S7S is kHz. And, data is clocked in on the rising edge of the clock when it goes from 0V to 5V. Thanks to the slave-select pin, we can connect multiple SPI devices on a single bus.
You could even connect multiple S7S's on the same bus, provided each had its own dedicated select pin. The I 2 C address of the S7S is configurable, but defaults to 0x Data on an I 2 C bus goes both ways, so special acknowledge signals are required to implement a form of handshaking. What I 2 C lacks in a CS wire, it more than makes up for in complexity of the data signal.
Happily though, there are many I 2 C libraries -- the Wire library for example on Arduino, which makes I 2 C data transfer simple. If you need to talk to four segments, program them with unique addresses and link away!
To interface other electronics to the display, you'll need to solder to some of the S7S's pins. Before you do any soldering, though, think on how you want to use the display. Do you plan on using one of the serial interfaces in particular? Maybe you only need to solder to the power pins, and the few pins which correspond to your preferred interface. Are you just prototyping with the display?
Are you mounting it in an project enclosure? Your assembly method really depends on what your final goals for the display are. For many use cases, you'll really only need the pins on the top header. When I prototype with these displays, I like to solder some straight male headers in, so I can stick it into a breadboard.
Of course, you could solder stranded or solid-core wires into the pins you need. This is useful if you plan on mounting the display in an enclosure. If you intend to ever reprogram the display using an FTDI Basic , you might find it useful to solder some right-angle male headers into the serial programming header.
This can be a bit tricky, as the display gets in the way. I solder my right-angler's on the curved side. Finally, if you'll be mounting the display, any screw should be able to find its way through those stand-off holes. If you're looking for an even simpler form factor of the S7S, take a look at the 7-Segment Shield display. It runs the same firmware as the OpenSegment and Serial 7-Segment displays and is controlled in the same manner.
It is arguably the easiest of the three to get up in running as all you have to do is populate the standard Arduino headers , a 7-segment display of your choice, and then plug the shield into an Arduino Uno compatible board. For more instructions on shield assembly, visit our shield tutorial.
Just like its brother boards, the serial 7-segment shield can be controlled via SPI, I2C, and serial communication. You can choose which communication protocol works best for your specific application leaving the others open to interact with other pieces of hardware. It shares the same command set, and all the same example Arduino sketches work for it as well without needing to change a single line of code.
In a very basic explanation, they all have many rows and columns of pixels driven by a controller that communicates with each pixel to emit the brightness and color needed to make up the transmitted image.
In all cases, a memory array stores the image information that travels to the display through an interface. According to Wikipedia, "an interface is a shared boundary across which two separate components of a computer system exchange information. The exchange can be between software, computer hardware, peripheral devices, humans, and combinations of these.
Some computer hardware devices such as a touchscreen can both send and receive data through the interface, while others such as a mouse or microphone may only provide an interface to send data to a given system. Although display interfaces serve a similar purpose, how that communication occurs varies widely.
Serial Peripheral Interface SPI is a synchronous serial communication interface best-suited for short distances. It was developed by Motorola for components to share data such as flash memory, sensors, Real-Time Clocks, analog-to-digital converters, and more. Because there is no protocol overhead, the transmission runs at relatively high speeds. SPI runs on one master the side that generates the clock with one or more slaves, usually the devices outside the central processor.
One drawback of SPI is the number of pins required between devices. It utilizes a multi-master, multi-slave, single-ended, serial computer bus system.
Engineers developed I2C for simple peripherals on PCs, like keyboards and mice to then later apply it to displays. Like SPI, it only works for short distances within a device and uses an asynchronous serial port.
Many display systems transfer the touch sensor data through I2C. RGB is used to interface with large color displays. However, waveforms can also have square forms, as in the following AC graph. With this AC driving waveform, there can be and is an overall zero V DD potential, protecting the liquid crystal material from damage. The LCD controller is a type of small MPU computer that is able to translate the software code of the user into usable information for the LCD, allowing the display to then show the correct graphics, characters, or images.
Without such a device, the thousands of pixels on a display would have to be communicated with individually, making a large and unified display difficult to produce. The controller stores the received data in random-access memory RAM where it can be retrieved to be read or written in a set amount of time regardless of location in the RAM. After the data is converted into a serial or parallel interface , it is then transferred to the LCD driver.
Taking in the converted interface from the controller, the driver will send a signal to direct the desired voltage, current, and timing to then display the proper image. There are two kinds of drivers: common and segment.
Common drivers send signals to create rows in the display, and segment drivers control the columns to create the character of the display. Drivers then control the data pins that load the data into a specific segment of the display based on the command. In the process of sending data through a network, two manners of doing so are through a parallel interface and a serial one.
They both complete the job, but have different methods and thus different advantages. In the transfer of data, the parallel interface will send data in multiple bits in one direction.
Serial interface sends data in one direction as well, but in a single string of bits. For example, if a word of five bits in length is sent, the parallel interface will transfer all five bits in five corresponding channels that each transfer the bit to be received simultaneously with the others in a single byte like in the initial signal.
The serial interface, on the other hand, will send each letter in order, one at a time. After all the bits are sent, they will be reassembled into one byte. For a diagram reference, see below. The parallel interface uses what is called spatial location to encode the bits by the various channels. Serial interface uses temporal location on the single channel, or the time between each signaled bit.
With this process explained, the parallel interface is much faster, and can send a maximum of x number of bits through x channels in the time a serial interface takes to send one bit through the single channel. However, the serial interface is much steadier, allowing for clearer signals.
The parallel interface can become overwhelmed with the number of connections channels used, and this can distort the transmission, making it less viable for long distance signals compared to the serial interface. In the MCU parallel interface for LCDs, data signals are sent using a data bus through either 8-bit, 9-bit, bit, or bit data channels.
This is one type of LCD controller signal; the other is the control signal which defines the operation, reading or writing. This type of interface is overall simple, but it required display RAM for its storage behavior.
It can be used in character LCDs using alphabet and numbers in the display only , graphic LCDs , and very small less than 3. All the interfaces have Vcc to provide power, gnd for grounding. If higher voltage needed, it has to be external or add DC-DC converter on board. Serial interface, as described prior, is a single channel of signals sent one by one to the receiving part of the device. It is called a serial interface because it sends a series of voltage pulses to transmit a message using temporal location.
Binary numbers 1 and 0 are used in this communication.
0コメント