236 lines
7.7 KiB
C
236 lines
7.7 KiB
C
/* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/** library to communicate with a Titan Micro MAX7219 IC attached to a 4-digit 7-segment (code)
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* @file led_max7219.c
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @date 2017
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* @note peripherals used: GPIO @ref led_max7219_gpio, timer @ref led_tm1637_timer
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* @warning all calls are blocking
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*
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* bit vs segment: 0bpabcdefg
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* +a+
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* f b
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* +g+
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* e c p
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* +d+
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*/
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/* standard libraries */
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#include <stdint.h> // standard integer types
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#include <stdlib.h> // general utilities
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#include <string.h> // string utilities
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/* STM32 (including CM3) libraries */
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#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
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#include <libopencm3/stm32/rcc.h> // real-time control clock library
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#include <libopencm3/stm32/gpio.h> // general purpose input output library
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#include <libopencm3/stm32/spi.h> // SPI library
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#include <libopencm3/stm32/timer.h> // timer library
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#include "global.h" // global utilities
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#include "led_max7219.h" // MAX7219 header and definitions
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/** @defgroup led_max7219_gpio GPIO used to control MAX7219 IC load line
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* @{
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*/
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#define LED_MAX7219_LOAD_PORT B /**< port for load line */
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#define LED_MAX7219_LOAD_PIN 12 /**< pin for load line */
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/** @} */
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/** @defgroup led_max7219_spi SPI used to communication with MAX7219 IC
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* @{
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*/
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#define LED_MAX7219_SPI 2 /**< SPI to send data */
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/** @} */
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/** ASCII characters encoded for the 7 segments digit block
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* @note starts with space
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*/
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static const uint8_t ascii_7segments[] = {
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0x00, // space
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0x06, // ! (I)
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0x22, // "
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0x1d, // # (o)
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0x5b, // $ (s)
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0x25, // % (/)
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0x5f, // & (6)
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0x02, // '
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0x4e, // ( ([)
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0x78, // )
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0x07, // *
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0x31, // +
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0x04, // ,
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0x01, // -
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0x04, // . (,)
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0x25, // /
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0x7e, // 0
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0x30, // 1
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0x6d, // 2
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0x79, // 3
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0x33, // 4
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0x5b, // 5
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0x5f, // 6
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0x70, // 7
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0x7f, // 8
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0x7b, // 9
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0x09, // : (=)
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0x09, // ; (=)
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0x0d, // <
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0x09, // =
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0x19, // >
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0x65, // ?
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0x6f, // @
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0x77, // A
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0x7f, // B
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0x4e, // C
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0x3d, // D
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0x4f, // E
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0x47, // F
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0x5e, // G
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0x37, // H
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0x06, // I
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0x3c, // J
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0x37, // K
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0x0e, // L
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0x76, // M
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0x76, // N
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0x7e, // O
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0x67, // P
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0x6b, // Q
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0x66, // R
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0x5b, // S
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0x0f, // T
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0x3e, // U
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0x3e, // V (U)
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0x3e, // W (U)
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0x37, // X (H)
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0x3b, // Y
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0x6d, // Z
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0x4e, // [
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0x13, // '\'
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0x78, // /
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0x62, // ^
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0x08, // _
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0x20, // `
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0x7d, // a
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0x1f, // b
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0x0d, // c
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0x3d, // d
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0x6f, // e
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0x47, // f
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0x7b, // g
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0x17, // h
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0x04, // i
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0x18, // j
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0x37, // k
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0x06, // l
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0x15, // m
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0x15, // n
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0x1d, // o
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0x67, // p
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0x73, // q
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0x05, // r
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0x5b, // s
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0x0f, // t
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0x1c, // u
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0x1c, // v (u)
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0x1c, // w (u)
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0x37, // x
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0x3b, // y
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0x6d, // z
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0x4e, // { ([)
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0x06, // |
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0x78, // } ([)
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0x01, // ~
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};
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/** write data on SPI bus and handle load signal
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* @param[in] data bytes to write
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*/
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static void led_max7219_write(uint16_t data)
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{
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gpio_clear(GPIO(LED_MAX7219_LOAD_PORT), GPIO(LED_MAX7219_LOAD_PIN)); // ensure load pin is low (data is put in MAX7219 register on rising edge)
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while (SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_BSY); // wait until not busy
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spi_send(SPI(LED_MAX7219_SPI), data); // send data
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while (!(SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_TXE)); // wait until Tx is empty (reference manual says BSY should also cover this, but it doesn't)
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while (SPI_SR(SPI(LED_MAX7219_SPI))&SPI_SR_BSY); // wait until not busy (= transmission completed)
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gpio_set(GPIO(LED_MAX7219_LOAD_PORT), GPIO(LED_MAX7219_LOAD_PIN)); // create rising edge on load pin for data to be set in MAX7219 register
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}
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void led_max7219_setup(void)
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{
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// configure GPIO for load line
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rcc_periph_clock_enable(RCC_GPIO(LED_MAX7219_LOAD_PORT)); // enable clock for GPIO peripheral
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gpio_clear(GPIO(LED_MAX7219_LOAD_PORT), GPIO(LED_MAX7219_LOAD_PIN)); // idle low (load on rising edge)
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gpio_set_mode(GPIO(LED_MAX7219_LOAD_PORT), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(LED_MAX7219_LOAD_PIN)); // set as output
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// configure SPI peripheral
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rcc_periph_clock_enable(RCC_SPI_SCK_PORT(LED_MAX7219_SPI)); // enable clock for GPIO peripheral for clock signal
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gpio_set_mode(SPI_SCK_PORT(LED_MAX7219_SPI), GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, SPI_SCK_PIN(LED_MAX7219_SPI)); // set as output (max clock speed for MAX7219 is 10 MHz)
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rcc_periph_clock_enable(RCC_SPI_MOSI_PORT(LED_MAX7219_SPI)); // enable clock for GPIO peripheral for MOSI signal
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gpio_set_mode(SPI_MOSI_PORT(LED_MAX7219_SPI), GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, SPI_MOSI_PIN(LED_MAX7219_SPI)); // set as output
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rcc_periph_clock_enable(RCC_AFIO); // enable clock for SPI alternate function
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rcc_periph_clock_enable(RCC_SPI(LED_MAX7219_SPI)); // enable clock for SPI peripheral
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spi_reset(SPI(LED_MAX7219_SPI)); // clear SPI values to default
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spi_init_master(SPI(LED_MAX7219_SPI), SPI_CR1_BAUDRATE_FPCLK_DIV_16, SPI_CR1_CPOL_CLK_TO_0_WHEN_IDLE, SPI_CR1_CPHA_CLK_TRANSITION_1, SPI_CR1_DFF_16BIT, SPI_CR1_MSBFIRST); // initialise SPI as master, divide clock by 8 since max MAX7219 clock is 10 MHz and max SPI PCLK clock is 72 Mhz, depending on which SPI is used, set clock polarity to idle high (polarity is not really important for the MAX7219), set clock phase to go high when bit is set (depends on polarity) as data is stored on MAX7219 on rising edge), use 16 bits frames (as used by MAX7219), use MSB first
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spi_set_unidirectional_mode(SPI(LED_MAX7219_SPI)); // we only need to transmit data
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spi_enable(SPI(LED_MAX7219_SPI)); // enable SPI
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// default setting
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led_max7219_off(); // switch display off
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led_max7219_test(false); // disable test mode
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led_max7219_intensity(15); // set maximum intensity
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led_max7219_write(0x0B07); // set scan limit to display all 7 digits
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}
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void led_max7219_on(void)
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{
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led_max7219_write(0x0C01); // set scan limit to display all 7 digits
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}
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void led_max7219_off(void)
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{
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led_max7219_write(0x0C00); // put in shutdown mode (registers remain as set)
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}
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void led_max7219_test(bool test)
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{
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if (test) {
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led_max7219_write(0x0F01); // go into display test mode
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} else {
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led_max7219_write(0x0F00); // go into normal operation mode
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}
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}
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void led_max7219_intensity(uint8_t intensity)
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{
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if (intensity>15) { // intensity must be 0-15 (corresponds to (2*brightness+1)/32)
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return;
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}
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led_max7219_write(0x0A00+intensity); // set brightness
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}
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void led_max7219_text(char* text)
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{
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for (uint8_t i=0; i<8; i++) { // input text should only contain printable character (8th bit is used for dots)
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if ((text[i]&0x7f)<' ' || (text[i]&0x7f)>=' '+LENGTH(ascii_7segments)) {
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return;
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}
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}
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led_max7219_write(0x0900); // disable BCD decoding on all 7 digits
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for (uint8_t i=0; i<8; i++) { // display text
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led_max7219_write(((i+1)<<8)+(ascii_7segments[(text[7-i]&0x7f)-' '])+(text[7-i]&0x80)); // send digit (in reverse order)
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}
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}
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