This repository provides two MPLAB® X projects for interfacing the Configurable Logic Block (CLB) and I/O Ports peripherals with a 7-segment display to show hexadecimal numbers:
The CLB peripheral is a collection of logic elements that can be programmed to perform a wide variety of digital logic functions. The logic function may be completely combinatorial, sequential, or a combination of the two, enabling users to incorporate hardware-based custom logic into their applications.
More details and code examples on the PIC16F13145 can be found at the following links:
- PIC16F13145 Product Page
- PIC16F13145 Code Examples on Discover
- PIC16F13145 Code Examples on GitHub
- 7-Segment Display Data Sheet
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The PIC16F13145 Curiosity Nano Development board is used as a test platform:
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7-Segment Display
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7 x 330 Ohm Resistors
To program the Curiosity Nano board with this MPLAB X project, follow the steps provided in the How to Program the Curiosity Nano Board chapter.
This example demonstrates the capabilities of the CLB, a Core Independent Peripheral (CIP), that can control and manipulate the transmitted data through the I/O Ports for the Software Input Register of the CLB (CLBSWIN). This software register is incremented with 1 after each iteration, between 0 and 15, values that are displayed in hexadecimal on the display.
This application includes two different solutions through the CLB peripheral. The first application uses seven different Look-up Table (LUT) embedded circuits for each pin of the display, and the second one uses only logic gates: AND, NOT, OR. Both implementations present the same result. The used display is Common Cathode, and in this type of display, all the cathode connections of the LED segments are connected together to logic 0 or ground. The separate segments are lightened by applying the logic 1 or HIGH signal through a current limiting resistor to forward bias the individual anode terminals a to g, as below.
The table below presents the truth table that correctly displays the hexadecimal number on a 7-segment display, depending on the input values.
| In | Out | Displayed Number | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWIN3 | SWIN2 | SWIN1 | SWIN0 | a | b | c | d | e | f | g | |
| 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 |
| 0 | 0 | 0 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 1 |
| 0 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 2 |
| 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 3 |
| 0 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 4 |
| 0 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 5 |
| 0 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 6 |
| 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 7 |
| 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 8 |
| 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 9 |
| 1 | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | A |
| 1 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | b |
| 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | c |
| 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | d |
| 1 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | E |
| 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | F |
Both projects implement the logic of the 7-segment decoder using the CLB peripheral, but in two different manners. The main idea of the application is to display all the hexadecimal values on a 7-segment display, using software data from the main project interfaced with the CLB.
The first project is described by seven LUTs circuits as in the figure below. Each LUT corresponds to one of the inputs of the 7-segment display, called from a to f, and its value is 1 or 0, according to the table above.
The second project is defined by the CLB that configures only logic gates (NOT, AND, OR) and presents a higher complexity than the first project. Each final output of the logic gates corresponds to one of the inputs of the 7-segment display, called from a to f, and its value is 1 or 0, according to the table above.
The following peripheral and clock configurations are set up using MPLAB Code Configurator (MCC) Melody for the PIC16F13145:
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Configurations Bits:
- CONFIG1:
- External Oscillator mode selection bits: Oscillator not enabled
- Power-up default value for COSC bits: HFINTOSC (1MHz)
- CONFIG2:
- Brown-out reset enable bits: Brown-out reset disabled
- Brown-out reset enable bits: Brown-out reset disabled
- CONFIG3:
- WDT operating mode: WDT Disabled, SEN is ignored
- WDT operating mode: WDT Disabled, SEN is ignored
- CONFIG1:
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Clock Control:
- Clock Source: HFINTOSC
- HF Internal Clock: 4_MHz
- Clock Divider: 1
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CLB1:
- Enable CLB: Enabled
- Clock Selection: HFINTOSC
- Clock Divider: Divide clock source by 4
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CRC:
- Auto-configured by CLB
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NVM:
- Auto-configured by CLB
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Pin Grid View:
- CLBPPSOUT0: RC0 (Signal to "a" pin of the display)
- CLBPPSOUT1: RC1 (Signal to "b" pin of the display)
- CLBPPSOUT2: RC2 (Signal to "c" pin of the display)
- CLBPPSOUT3: RC3 (Signal to "d" pin of the display)
- CLBPPSOUT4: RC4 (Signal to "e" pin of the display)
- CLBPPSOUT5: RC5 (Signal to "f" pin of the display)
- CLBPPSOUT6: RC6 (Signal to "g" pin of the display)
The demo below presents the incrementing numbers in hexadecimal between 0 and 0xF (hexadecimal values) that are shown on the 7-segment display. The 330 Ohm resistors are needed to limit the current between each LED and I/O pins of the microcontroller.
Note: The demo is at 2x speed.
This example demonstrates the capabilities of the CLB, a CIP that can manipulate the data from the software, while also displaying it in a 7-segment LED view.
This chapter demonstrates how to use the MPLAB X IDE to program a PIC® device with an Example_Project.X. This is applicable to other projects.
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Connect the board to the PC.
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Open the Example_Project.X project in MPLAB X IDE.
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Set the Example_Project.X project as main project.
Right click the project in the Projects tab and click Set as Main Project.
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Clean and build the Example_Project.X project.
Right click the Example_Project.X project and select Clean and Build.
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Select PICxxxxx Curiosity Nano in the Connected Hardware Tool section of the project settings:
Right click the project and click Properties.
Click the arrow under the Connected Hardware Tool.
Select PICxxxxx Curiosity Nano (click the SN), click Apply and then click OK:
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Program the project to the board.
Right click the project and click Make and Program Device.
