hobbielektronika / Mbed 2 deprecated 06_spi_max7219_led8x8

Simple demo to drive a 8x8-as LED matrix by a MAX7219 LED driver IC. After initialisation two characters (H and W) are displayed alternatively. The MAX7219 IC is driven by hardware SPI: SPI0 module at PTD1, PTD2, PTD3.

Dependencies:   mbed

SPI MAX7219 demo

Simple demo to drive a 8x8-as LED matrix by a MAX7219 LED driver IC. After initialisation two characters (H and W) are displayed alternatively. The MAX7219 IC is driven by hardware SPI: SPI0 module at PTD1, PTD2, PTD3 (Arduino compatible pins).

Hardware requirements:

  • FRDM-KL25Z board
  • LED 8x8 matrix with MAX7219 controller

Wiring:

MAX7219FRDM-KL25zNote
VCC3V3Power
GNDGNDGround
DIND11MOSI (PTD2)
CSD10Chip select (PTD0)
CLKD13SCLK (PTD1)

/media/uploads/icserny/led8x8.jpg

main.cpp@0:bd34a367f642, 2015-11-24 (annotated)

Committer:
icserny
Date:
Tue Nov 24 06:41:43 2015 +0000
Revision:
0:bd34a367f642
First version

Who changed what in which revision?

UserRevisionLine numberNew contents of line
icserny 0:bd34a367f642 1 /* 06_spi_max7219_led8x8
icserny 0:bd34a367f642 2 *
icserny 0:bd34a367f642 3 * Simple demo to drive a 8x8-as LED matrix by a MAX7219 LED driver IC
icserny 0:bd34a367f642 4 * After initialisation two characters (H and W) are displayed alternatively.
icserny 0:bd34a367f642 5 * The MAX7219 IC is driven by hardware SPI: SPI0 module at PTD1, PTD2, PTD3.
icserny 0:bd34a367f642 6 */
icserny 0:bd34a367f642 7
icserny 0:bd34a367f642 8 #include "mbed.h"
icserny 0:bd34a367f642 9
icserny 0:bd34a367f642 10 SPI spi(PTD2, PTD3, PTD1); // Arduino compatible MOSI, MISO, SCLK
icserny 0:bd34a367f642 11 DigitalOut cs(PTD0); // Chip select
icserny 0:bd34a367f642 12
icserny 0:bd34a367f642 13 const unsigned char led1[]= {
icserny 0:bd34a367f642 14 0xFF,0x18,0x18,0x18,0x18,0x18,0x18,0xFF
icserny 0:bd34a367f642 15 }; //H
icserny 0:bd34a367f642 16 const unsigned char led2[]= {
icserny 0:bd34a367f642 17 0x1F,0x60,0x80,0x40,0x40,0x80,0x60,0x1F
icserny 0:bd34a367f642 18 }; //W
icserny 0:bd34a367f642 19
icserny 0:bd34a367f642 20 /// Send two bytes to SPI bus
icserny 0:bd34a367f642 21 void SPI_Write2(unsigned char MSB, unsigned char LSB)
icserny 0:bd34a367f642 22 {
icserny 0:bd34a367f642 23 cs = 0; // Set CS Low
icserny 0:bd34a367f642 24 spi.write(MSB); // Send two bytes
icserny 0:bd34a367f642 25 spi.write(LSB);
icserny 0:bd34a367f642 26 cs = 1; // Set CS High
icserny 0:bd34a367f642 27 }
icserny 0:bd34a367f642 28
icserny 0:bd34a367f642 29 /// MAX7219 initialisation
icserny 0:bd34a367f642 30 void Init_MAX7219(void)
icserny 0:bd34a367f642 31 {
icserny 0:bd34a367f642 32 SPI_Write2(0x09, 0x00); // Decoding off
icserny 0:bd34a367f642 33 SPI_Write2(0x0A, 0x08); // Brightness to intermediate
icserny 0:bd34a367f642 34 SPI_Write2(0x0B, 0x07); // Scan limit = 7
icserny 0:bd34a367f642 35 SPI_Write2(0x0C, 0x01); // Normal operation mode
icserny 0:bd34a367f642 36 SPI_Write2(0x0F, 0x0F); // Enable display test
icserny 0:bd34a367f642 37 wait_ms(500); // 500 ms delay
icserny 0:bd34a367f642 38 SPI_Write2(0x01, 0x00); // Clear row 0.
icserny 0:bd34a367f642 39 SPI_Write2(0x02, 0x00); // Clear row 1.
icserny 0:bd34a367f642 40 SPI_Write2(0x03, 0x00); // Clear row 2.
icserny 0:bd34a367f642 41 SPI_Write2(0x04, 0x00); // Clear row 3.
icserny 0:bd34a367f642 42 SPI_Write2(0x05, 0x00); // Clear row 4.
icserny 0:bd34a367f642 43 SPI_Write2(0x06, 0x00); // Clear row 5.
icserny 0:bd34a367f642 44 SPI_Write2(0x07, 0x00); // Clear row 6.
icserny 0:bd34a367f642 45 SPI_Write2(0x08, 0x00); // Clear row 7.
icserny 0:bd34a367f642 46 SPI_Write2(0x0F, 0x00); // Disable display test
icserny 0:bd34a367f642 47 wait_ms(500); // 500 ms delay
icserny 0:bd34a367f642 48 }
icserny 0:bd34a367f642 49
icserny 0:bd34a367f642 50 int main()
icserny 0:bd34a367f642 51 {
icserny 0:bd34a367f642 52 cs = 1; // CS initially High
icserny 0:bd34a367f642 53 spi.format(8,0); // 8-bit format, mode 0,0
icserny 0:bd34a367f642 54 spi.frequency(1000000); // SCLK = 1 MHz
icserny 0:bd34a367f642 55 Init_MAX7219(); // Initialize the LED controller
icserny 0:bd34a367f642 56 while (1) {
icserny 0:bd34a367f642 57 for(int i=1; i<9; i++) // Write first character (8 rows)
icserny 0:bd34a367f642 58 SPI_Write2(i,led1[i-1]);
icserny 0:bd34a367f642 59 wait(1); // 1 sec delay
icserny 0:bd34a367f642 60 for(int i=1; i<9; i++) // Write second character
icserny 0:bd34a367f642 61 SPI_Write2(i,led2[i-1]);
icserny 0:bd34a367f642 62 wait(1); // 1 sec delay
icserny 0:bd34a367f642 63 }
icserny 0:bd34a367f642 64 }
icserny 0:bd34a367f642 65
icserny 0:bd34a367f642 66
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