hobbielektronika
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:
| MAX7219 | FRDM-KL25z | Note |
|---|---|---|
| VCC | 3V3 | Power |
| GND | GND | Ground |
| DIN | D11 | MOSI (PTD2) |
| CS | D10 | Chip select (PTD0) |
| CLK | D13 | SCLK (PTD1) |
Revision 0:bd34a367f642, committed 2015-11-24
- Comitter:
- icserny
- Date:
- Tue Nov 24 06:41:43 2015 +0000
- Commit message:
- First version
Changed in this revision
| main.cpp | Show annotated file Show diff for this revision Revisions of this file |
| mbed.bld | Show annotated file Show diff for this revision Revisions of this file |
diff -r 000000000000 -r bd34a367f642 main.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Tue Nov 24 06:41:43 2015 +0000
@@ -0,0 +1,70 @@
+/* 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.
+ */
+
+#include "mbed.h"
+
+SPI spi(PTD2, PTD3, PTD1); // Arduino compatible MOSI, MISO, SCLK
+DigitalOut cs(PTD0); // Chip select
+
+const unsigned char led1[]= {
+ 0xFF,0x18,0x18,0x18,0x18,0x18,0x18,0xFF
+}; //H
+const unsigned char led2[]= {
+ 0x1F,0x60,0x80,0x40,0x40,0x80,0x60,0x1F
+}; //W
+
+/// Send two bytes to SPI bus
+void SPI_Write2(unsigned char MSB, unsigned char LSB)
+{
+ cs = 0; // Set CS Low
+ spi.write(MSB); // Send two bytes
+ spi.write(LSB);
+ cs = 1; // Set CS High
+}
+
+/// MAX7219 initialisation
+void Init_MAX7219(void)
+{
+ SPI_Write2(0x09, 0x00); // Decoding off
+ SPI_Write2(0x0A, 0x08); // Brightness to intermediate
+ SPI_Write2(0x0B, 0x07); // Scan limit = 7
+ SPI_Write2(0x0C, 0x01); // Normal operation mode
+ SPI_Write2(0x0F, 0x0F); // Enable display test
+ wait_ms(500); // 500 ms delay
+ SPI_Write2(0x01, 0x00); // Clear row 0.
+ SPI_Write2(0x02, 0x00); // Clear row 1.
+ SPI_Write2(0x03, 0x00); // Clear row 2.
+ SPI_Write2(0x04, 0x00); // Clear row 3.
+ SPI_Write2(0x05, 0x00); // Clear row 4.
+ SPI_Write2(0x06, 0x00); // Clear row 5.
+ SPI_Write2(0x07, 0x00); // Clear row 6.
+ SPI_Write2(0x08, 0x00); // Clear row 7.
+ SPI_Write2(0x0F, 0x00); // Disable display test
+ wait_ms(500); // 500 ms delay
+}
+
+int main()
+{
+ cs = 1; // CS initially High
+ spi.format(8,0); // 8-bit format, mode 0,0
+ spi.frequency(1000000); // SCLK = 1 MHz
+ Init_MAX7219(); // Initialize the LED controller
+ while (1) {
+ for(int i=1; i<9; i++) // Write first character (8 rows)
+ SPI_Write2(i,led1[i-1]);
+ wait(1); // 1 sec delay
+ for(int i=1; i<9; i++) // Write second character
+ SPI_Write2(i,led2[i-1]);
+ wait(1); // 1 sec delay
+ }
+}
+
+
+
+
+
+
diff -r 000000000000 -r bd34a367f642 mbed.bld --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Tue Nov 24 06:41:43 2015 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/9296ab0bfc11 \ No newline at end of file