Table of Contents
Overview
This is a simple project on the seven segment display interface with tms320f28335. The tutorial presents a simple example of printing numeric numbers on a seven-segment display. The tutorial task is to print numbers from 0 to 9 on a single seven-segment display. There are two types of seven-segment displays, Common Anode and Common Cathode.
Required Hardware Components
Hardware
- Launchxl-F28379D
- 7 Segment Display
Software:
- Code Composer Studio
Specifications:
TMS320F28335 Microcontroller
On-chip memory
- 256K × 16 Flash, 34K × 16 SARAM
- Clock frequency: Up to 150 MHz (6.67-ns cycle time)
- Operating voltage: 1.9-V/1.8-V core, 3.3-V I/O design
- Six-channel DMA controller (for ADC, McBSP, ePWM, XINTF, and SARAM)
Communications peripherals
- Up to 2 CAN modules
- Up to 3 SCI (UART) modules
- Up to 2 McBSP modules (configurable as SPI)
- One SPI module
- One Inter-Integrated Circuit (I2C) bus
Analog subsystem
- 12-bit ADC, 16 channels
- 80-ns conversion rate
- 2 × 8 channel input multiplexer
- Two sample-and-hold
- Single/simultaneous conversions
- Internal or external reference
Enhanced control peripherals (EPWM)
- Up to 18 PWM outputs
- Up to 6 HRPWM outputs with 150-ps MEP resolution
- 16-bit or 32-bit External Interface (XINTF)
- GPIO0 to GPIO63 pins can be connected to one of the eight external core interrupts
- Up to 18 PWM outputs
- Up to 6 HRPWM outputs with 150-ps MEP
- Up to 88 individually programmable, multiplexed GPIO pins with input filtering
Three 32 bit CPU Timers
Gpio Connection:
| S.No | Gpio_connection | Dsp_connection |
| 1. | Gpio_01( output) | Gpio_01( output) |
| 2. | Gpio_02( output) | Gpio_02( output) |
| 3. | Gpio_04( output) | Gpio_04( output) |
| 4. | Gpio_06( output) | Gpio_06( output) |
| 5. | Gpio_07( output) | Gpio_07( output) |
| 6. | Gpio_09( output) | Gpio_09( output) |
| 7. | Gpio_10( output) | Gpio_10( output) |
Block diagram:
About 7 segment display:
Seven segment displays are the output display device that provides a way to display information in the form of image or text or decimal numbers. It consists of seven segments of light-emitting diodes (LED s) which are assembled like numerical 8. Since seven segment displays can not form alphabets like X and Z, so they can not be used for the alphabet and they can be used only for displaying decimal numerical magnitudes. However, seven-segment displays can form alphabets A, B, C, D, E, and F, so they can also use for representing hexadecimal digits. The Working of Seven Segment Displays is explained below.
Common Cathode 7-segment Display
The Common Anode (CA) – In the common anode display, all the anode connections of the LED segments are joined together to logic “1”. The individual segments are illuminated by applying a ground, logic “0” or “LOW” signal via a suitable current limiting resistor to the Cathode of the particular segment (a-g).
Common Anode 7-segment Display
In general, common anode displays are more popular as many logic circuits can sink more current than they can source. Also note that a common cathode display is not a direct replacement in a circuit for a common anode display and vice versa, as it is the same as connecting the LEDs in reverse, and hence light emission will not take place.
Depending upon the decimal digit to be displayed, the particular set of LEDs is forward biased. For instance, to display the numerical digit 0, we will need to light up six of the LED segments corresponding to a, b, c, d, e and f. Then the various digits from 0 through 9 can be displayed using a 7-segment display as shown.
Step by step execution process:
Step 1: Initialize the GPIO pin(select the pin number).
Step 2: Select the pin as an output(means 1).
Step 3: Repeat steps 1 and 2 for selecting multiple pins.
Step 4: Connect the pins to the seven segments LED display according to the respective LED segments.
Step 5: Put CLEAR command for turning on the LED segment.
Step 6: Put SET command for turning off the LED segment.
Step 7: Set commands for displaying different digits.
Step 8: Keep a delay 1 second after each digit is displayed.
Step 9: Execute the final code and verify the output.
Final code:
#include "DSP28x_Project.h" //Device headerfile*
void main(void)
{
InitSysCtrl();
// gpio configuration
EALLOW;
GpioCtrlRegs.GPAMUX1.bit.GPIO1=0; // selecting the gpio pin
GpioCtrlRegs.GPADIR.bit.GPIO1=1; //1 mean output pin,0 mean input
GpioCtrlRegs.GPAPUD.bit.GPIO1=0; // input selection completed
GpioCtrlRegs.GPAMUX1.bit.GPIO2=0; // selecting the gpio pin
GpioCtrlRegs.GPADIR.bit.GPIO2=1; //1 mean output pin,0 mean input pin
GpioCtrlRegs.GPAPUD.bit.GPIO2=0; // input selection completed
GpioCtrlRegs.GPAMUX1.bit.GPIO4=0; // selecting the gpio pin
GpioCtrlRegs.GPADIR.bit.GPIO4=1; //1 mean output pin,0 mean input pin
GpioCtrlRegs.GPAPUD.bit.GPIO4=0; // input selection completed
GpioCtrlRegs.GPAMUX1.bit.GPIO6=0; // selecting the gpio pin
GpioCtrlRegs.GPADIR.bit.GPIO6=1; //1 mean output pin,0 mean input pin
GpioCtrlRegs.GPAPUD.bit.GPIO6=0; // input selection completed
GpioCtrlRegs.GPAMUX1.bit.GPIO7=0; // selecting the gpio pin
GpioCtrlRegs.GPADIR.bit.GPIO7=1; //1 mean output pin,0 mean input pin
GpioCtrlRegs.GPAPUD.bit.GPIO7=0; // input selection completed
GpioCtrlRegs.GPAMUX1.bit.GPIO9=0; // selecting the gpio pin
GpioCtrlRegs.GPADIR.bit.GPIO9=1; //1 mean output pin,0 mean input pin
GpioCtrlRegs.GPAPUD.bit.GPIO9=0; // input selection completed
GpioCtrlRegs.GPAMUX1.bit.GPIO10=0; // selecting the gpio pin
GpioCtrlRegs.GPADIR.bit.GPIO10=1; //1 mean output pin,0 mean input pin
GpioCtrlRegs.GPAPUD.bit.GPIO10=0; // input selection completed
EDIS;
while(1)
{
// 0
GpioDataRegs.GPACLEAR.bit.GPIO1=1;
GpioDataRegs.GPACLEAR.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPACLEAR.bit.GPIO5=1;
GpioDataRegs.GPACLEAR.bit.GPIO6=1;
GpioDataRegs.GPACLEAR.bit.GPIO7=1;
GpioDataRegs.GPACLEAR.bit.GPIO9=1;
GpioDataRegs.GPASET.bit.GPIO10=1;
DELAY_US(1000000);
// 1
GpioDataRegs.GPASET.bit.GPIO1=1;
GpioDataRegs.GPASET.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPASET.bit.GPIO5=1;
GpioDataRegs.GPACLEAR.bit.GPIO6=1;
GpioDataRegs.GPASET.bit.GPIO7=1;
GpioDataRegs.GPASET.bit.GPIO9=1;
GpioDataRegs.GPASET.bit.GPIO10=1;
DELAY_US(1000000);
// 2
GpioDataRegs.GPACLEAR.bit.GPIO1=1;
GpioDataRegs.GPACLEAR.bit.GPIO2=1;
GpioDataRegs.GPASET.bit.GPIO4=1;
GpioDataRegs.GPASET.bit.GPIO5=1;
GpioDataRegs.GPACLEAR.bit.GPIO6=1;
GpioDataRegs.GPACLEAR.bit.GPIO7=1;
GpioDataRegs.GPASET.bit.GPIO9=1;
GpioDataRegs.GPACLEAR.bit.GPIO10=1;
DELAY_US(1000000);
// 3
GpioDataRegs.GPASET.bit.GPIO1=1;
GpioDataRegs.GPACLEAR.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPASET.bit.GPIO5=1;
GpioDataRegs.GPACLEAR.bit.GPIO6=1;
GpioDataRegs.GPACLEAR.bit.GPIO7=1;
GpioDataRegs.GPASET.bit.GPIO9=1;
GpioDataRegs.GPACLEAR.bit.GPIO10=1;
DELAY_US(1000000);
// 4
GpioDataRegs.GPASET.bit.GPIO1=1;
GpioDataRegs.GPASET.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPASET.bit.GPIO5=1;
GpioDataRegs.GPACLEAR.bit.GPIO6=1;
GpioDataRegs.GPASET.bit.GPIO7=1;
GpioDataRegs.GPACLEAR.bit.GPIO9=1;
GpioDataRegs.GPACLEAR.bit.GPIO10=1;
DELAY_US(1000000);
// 5
GpioDataRegs.GPASET.bit.GPIO1=1;
GpioDataRegs.GPACLEAR.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPASET.bit.GPIO5=1;
GpioDataRegs.GPASET.bit.GPIO6=1;
GpioDataRegs.GPACLEAR.bit.GPIO7=1;
GpioDataRegs.GPACLEAR.bit.GPIO9=1;
GpioDataRegs.GPACLEAR.bit.GPIO10=1;
DELAY_US(1000000);
// 6
GpioDataRegs.GPACLEAR.bit.GPIO1=1;
GpioDataRegs.GPACLEAR.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPASET.bit.GPIO5=1;
GpioDataRegs.GPASET.bit.GPIO6=1;
GpioDataRegs.GPACLEAR.bit.GPIO7=1;
GpioDataRegs.GPACLEAR.bit.GPIO10=1;
DELAY_US(1000000);
// 7
GpioDataRegs.GPASET.bit.GPIO1=1;
GpioDataRegs.GPASET.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPASET.bit.GPIO5=1;
GpioDataRegs.GPACLEAR.bit.GPIO6=1;
GpioDataRegs.GPACLEAR.bit.GPIO7=1;
GpioDataRegs.GPASET.bit.GPIO9=1;
GpioDataRegs.GPASET.bit.GPIO10=1;
DELAY_US(1000000);
// 8
GpioDataRegs.GPACLEAR.bit.GPIO1=1;
GpioDataRegs.GPACLEAR.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPACLEAR.bit.GPIO5=1;
GpioDataRegs.GPACLEAR.bit.GPIO6=1;
GpioDataRegs.GPACLEAR.bit.GPIO7=1;
GpioDataRegs.GPACLEAR.bit.GPIO9=1;
GpioDataRegs.GPACLEAR.bit.GPIO10=1;
DELAY_US(1000000);
// 9
GpioDataRegs.GPASET.bit.GPIO1=1;
GpioDataRegs.GPACLEAR.bit.GPIO2=1;
GpioDataRegs.GPACLEAR.bit.GPIO4=1;
GpioDataRegs.GPACLEAR.bit.GPIO5=1;
GpioDataRegs.GPACLEAR.bit.GPIO6=1;
GpioDataRegs.GPACLEAR.bit.GPIO7=1;
GpioDataRegs.GPACLEAR.bit.GPIO9=1;
GpioDataRegs.GPACLEAR.bit.GPIO10=1;
DELAY_US(1000000);
}
}
