142 lines
4.2 KiB
C
142 lines
4.2 KiB
C
/**
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* Copyright (c) 2022 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdio.h>
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#include <string.h>
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#include "pico/stdlib.h"
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#include "pico/binary_info.h"
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#include "hardware/spi.h"
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/* Example code to talk to a Max7219 driving an 32x8 pixel LED display via SPI
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NOTE: The device is driven at 5v, but SPI communications are at 3v3
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Connections on Raspberry Pi Pico board and a generic Max7219 board, other
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boards may vary.
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* GPIO 17 (pin 22) Chip select -> CS on Max7219 board
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* GPIO 18 (pin 24) SCK/spi0_sclk -> CLK on Max7219 board
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* GPIO 19 (pin 25) MOSI/spi0_tx -> DIN on Max7219 board
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* 5v (pin 40) -> VCC on Max7219 board
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* GND (pin 38) -> GND on Max7219 board
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Note: SPI devices can have a number of different naming schemes for pins. See
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the Wikipedia page at https://en.wikipedia.org/wiki/Serial_Peripheral_Interface
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for variations.
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*/
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// This defines how many Max7219 modules we have cascaded together, in this case, we have 4 x 8x8 matrices giving a total of 32x8
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#define NUM_MODULES 4
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const uint8_t CMD_NOOP = 0;
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const uint8_t CMD_DIGIT0 = 1; // Goes up to 8, for each line
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const uint8_t CMD_DECODEMODE = 9;
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const uint8_t CMD_BRIGHTNESS = 10;
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const uint8_t CMD_SCANLIMIT = 11;
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const uint8_t CMD_SHUTDOWN = 12;
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const uint8_t CMD_DISPLAYTEST = 15;
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#ifdef PICO_DEFAULT_SPI_CSN_PIN
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static inline void cs_select() {
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asm volatile("nop \n nop \n nop");
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gpio_put(PICO_DEFAULT_SPI_CSN_PIN, 0); // Active low
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asm volatile("nop \n nop \n nop");
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}
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static inline void cs_deselect() {
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asm volatile("nop \n nop \n nop");
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gpio_put(PICO_DEFAULT_SPI_CSN_PIN, 1);
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asm volatile("nop \n nop \n nop");
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}
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#endif
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#if defined(spi_default) && defined(PICO_DEFAULT_SPI_CSN_PIN)
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static void write_register(uint8_t reg, uint8_t data) {
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uint8_t buf[2];
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buf[0] = reg;
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buf[1] = data;
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cs_select();
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spi_write_blocking(spi_default, buf, 2);
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cs_deselect();
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sleep_ms(1);
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}
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static void write_register_all(uint8_t reg, uint8_t data) {
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uint8_t buf[2];
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buf[0] = reg;
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buf[1] = data;
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cs_select();
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for (int i = 0; i< NUM_MODULES;i++) {
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spi_write_blocking(spi_default, buf, 2);
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}
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cs_deselect();
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}
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#endif
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int main() {
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stdio_init_all();
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#if !defined(spi_default) || !defined(PICO_DEFAULT_SPI_SCK_PIN) || !defined(PICO_DEFAULT_SPI_TX_PIN) || !defined(PICO_DEFAULT_SPI_CSN_PIN)
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#warning spi/max7219_32x8_spi example requires a board with SPI pins
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puts("Default SPI pins were not defined");
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#else
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printf("Hello, max7219! Drawing things on a LED matrix since 2022...\n");
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// This example will use SPI0 at 10MHz.
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spi_init(spi_default, 10 * 1000 * 1000);
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gpio_set_function(PICO_DEFAULT_SPI_SCK_PIN, GPIO_FUNC_SPI);
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gpio_set_function(PICO_DEFAULT_SPI_TX_PIN, GPIO_FUNC_SPI);
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// Make the SPI pins available to picotool
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bi_decl(bi_2pins_with_func(PICO_DEFAULT_SPI_TX_PIN, PICO_DEFAULT_SPI_SCK_PIN, GPIO_FUNC_SPI));
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// Chip select is active-low, so we'll initialise it to a driven-high state
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gpio_init(PICO_DEFAULT_SPI_CSN_PIN);
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gpio_set_dir(PICO_DEFAULT_SPI_CSN_PIN, GPIO_OUT);
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gpio_put(PICO_DEFAULT_SPI_CSN_PIN, 1);
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// Make the CS pin available to picotool
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bi_decl(bi_1pin_with_name(PICO_DEFAULT_SPI_CSN_PIN, "SPI CS"));
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// Send init sequence to device
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write_register_all(CMD_SHUTDOWN, 0);
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write_register_all(CMD_DISPLAYTEST, 0);
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write_register_all(CMD_SCANLIMIT, 7); // Use all lines
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write_register_all(CMD_DECODEMODE, 0); // No BCD decode, just use bit pattern.
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write_register_all(CMD_SHUTDOWN, 1);
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write_register_all(CMD_BRIGHTNESS, 8);
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for (int i=0; i<256; i++) {
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for (int j=0; j<8; j++) {
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write_register_all(CMD_DIGIT0+j, i);
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}
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sleep_ms(20);
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}
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int bright = 1;
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while (true) {
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for (int i=0; i<8; i++) {
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if (bright & 1) {
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write_register_all(CMD_DIGIT0 + i, 170 >> (i%2));
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} else {
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write_register_all(CMD_DIGIT0 + i, (170 >> 1) << (i%2));
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}
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write_register_all(CMD_BRIGHTNESS, bright % 16);
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}
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sleep_ms(250);
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bright++;
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}
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return 0;
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#endif
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}
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