diagram.json

#include <stm32f1xx.h>
#include "gpio.h"

typedef GPIO_TypeDef gpio_t;
#define GPIO(x) ((gpio_t *) (0x40010800 + 0x400 * (x)))

typedef enum {
	INPUT,
	OUTPUT_10MHZ,
	OUTPUT_2MHZ,
	OUTPUT_50MHZ,
} gpio_crx_mod_t;

typedef enum {
	INPUT_ANALOG = 0,
	INPUT_FLOAT = 1,
	INPUT_PULL = 2,
	OUTPUT_PUSHPULL = 0,
	OUTPUT_OPENDRAIN = 1,
	ALTERNATE_OUTPUT_PUSHPULL = 2,
	ALTERNATE_OUTPUT_OPENDRAIN = 3,
} gpio_crx_cnf_t;

void port_enable(port_t port) {
	if (port == PortA) RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;
	if (port == PortB) RCC->APB2ENR |= RCC_APB2ENR_IOPBEN;
	if (port == PortC) RCC->APB2ENR |= RCC_APB2ENR_IOPCEN;
	if (port == PortD) RCC->APB2ENR |= RCC_APB2ENR_IOPDEN;
}

void pin_mode(pin_t pin, pin_mode_t mode) {
	gpio_crx_mod_t mod = 0;
	gpio_crx_cnf_t cnf = 0;
	switch (mode) {
		case Input:
			mod = INPUT; cnf = INPUT_FLOAT;
			break;
		case InputPullUp:
			mod = INPUT; cnf = INPUT_PULL;
			break;
		case InputPullDown:
			mod = INPUT; cnf = INPUT_PULL;
			break;
		case InputAnalog:
			mod = INPUT; cnf = INPUT_ANALOG;
			break;
		case Output:
			mod = OUTPUT_10MHZ; cnf = OUTPUT_PUSHPULL;
			break;
		case OutputOpenDrain:
 			mod = OUTPUT_10MHZ; cnf = OUTPUT_OPENDRAIN;
			break;
		case AlternateOutput:
 			mode = OUTPUT_10MHZ; cnf = ALTERNATE_OUTPUT_PUSHPULL;
			break;
		case AlternateOutputOpenDrain:
 			mod = OUTPUT_10MHZ; cnf = ALTERNATE_OUTPUT_OPENDRAIN;
			break;
	}
	uint32_t val, mask;
	gpio_t * gpio = GPIO(pin_port(pin));
	if (pin_number(pin) < 8) {
		val = ((cnf << 2) + mod) << (4 * pin_number(pin));
		mask = 0xf << (4 * pin_number(pin));
		gpio->CRL = (gpio->CRL & ~mask) | val;
	} else {
		val = ((cnf << 2) + mod) << (4 * (pin_number(pin) - 8));
		mask = 0xf << (4 * (pin_number(pin) - 8));
		gpio->CRH = (gpio->CRH & ~mask) | val;
	}
}

void pin_set(pin_t pin) {
	gpio_t * gpio = GPIO(pin_port(pin));
	gpio->BSRR |= pin_mask(pin);
}

void pin_reset(pin_t pin) {
	gpio_t * gpio = GPIO(pin_port(pin));
	gpio->BRR |= pin_mask(pin);
}


gpio.c

#ifndef _gpio_h
#define _gpio_h

typedef enum {
	PortA = 0,
	PortB = 1,
	PortC = 2,
	PortD = 2,
} port_t;

typedef enum {
	PinA0  = 0x0000,
	PinA1  = 0x0001,
	PinA2  = 0x0002,
	PinA3  = 0x0003,
	PinA4  = 0x0004,
	PinA5  = 0x0005,
	PinA6  = 0x0006,
	PinA7  = 0x0007,
	PinA8  = 0x0008,
	PinA9  = 0x0009,
	PinA10 = 0x000A,
	PinA11 = 0x000B,
	PinA12 = 0x000C,
	PinA13 = 0x000D,
	PinA14 = 0x000E,
	PinA15 = 0x000F,
	PinB0  = 0x0100,
	PinB1  = 0x0101,
	PinB2  = 0x0102,
	PinB3  = 0x0103,
	PinB4  = 0x0104,
	PinB5  = 0x0105,
	PinB6  = 0x0106,
	PinB7  = 0x0107,
	PinB8  = 0x0108,
	PinB9  = 0x0109,
	PinB10 = 0x010A,
	PinB11 = 0x010B,
	PinB12 = 0x010C,
	PinB13 = 0x010D,
	PinB14 = 0x010E,
	PinB15 = 0x010F,
	PinC0  = 0x0200,
	PinC1  = 0x0201,
	PinC2  = 0x0202,
	PinC3  = 0x0203,
	PinC4  = 0x0204,
	PinC5  = 0x0205,
	PinC6  = 0x0206,
	PinC7  = 0x0207,
	PinC8  = 0x0208,
	PinC9  = 0x0209,
	PinC10 = 0x020A,
	PinC11 = 0x020B,
	PinC12 = 0x020C,
	PinC13 = 0x020D,
	PinC14 = 0x020E,
	PinC15 = 0x020F,
	PinD0  = 0x0300,
	PinD1  = 0x0301,
	PinD2  = 0x0302,
	PinD3  = 0x0303,
	PinD4  = 0x0304,
	PinD5  = 0x0305,
	PinD6  = 0x0306,
	PinD7  = 0x0307,
	PinD8  = 0x0308,
	PinD9  = 0x0309,
	PinD10 = 0x030A,
	PinD11 = 0x030B,
	PinD12 = 0x030C,
	PinD13 = 0x030D,
	PinD14 = 0x030E,
	PinD15 = 0x030F,
} pin_t;

typedef enum {
	Input,
	InputFloat = Input,
	InputPullUp,
	InputPullDown,
	InputAnalog,
	Output ,
	OutputOpenDrain,
	AlternateOutput,
	AlternateOutputPushPull = AlternateOutput,
	AlternateOutputOpenDrain,
} pin_mode_t;

#define pin_port(pin) ((port_t) (pin >> 8))
#define pin_number(pin) (pin & 0xFF)
#define pin_mask(pin) ((uint16_t)(1 << pin_number(pin)))
#ifdef __cplusplus
extern "C" {
#endif
void port_enable(port_t port);
void port_disable(port_t port);
void pin_mode(pin_t pin, pin_mode_t mode);
void pin_set(pin_t pin);
void pin_reset(pin_t pin);
#ifdef __cplusplus
extern "C" {
#endif
#endif


gpio.h

#include "ili9341.h"
#include "gpio.h"
#include "spi.h"
#include <stdint.h>
#include <stdbool.h>

#define BIT(x) (1<<x)

pin_t _cspin;
pin_t _dcpin;

typedef enum {
	NOP = 0x00,
	SOFTWARE_RESET = 0x01,
	READ_INDENTIFICATION = 0x04,
	READ_DISPLAY_STATUS = 0x09,
	READ_DISPLAY_POWER_MODE = 0xa,
	READ_MEMORY_ACCESS_CONTROL = 0x0b,
	READ_DISPLAY_PIXEL_FORMAT = 0xc,
	READ_DISPLAY_IMAGE_FORMAT = 0xc,
	READ_SELF_DIAGNOSTIC = 0xF,
	//
	ENTER_SLEEP_MODE = 0x10,
	SLEEP_OUT = 0x11,
	PARTIAL_DISPLAY_MODE_ON = 0x12,
	NORMAL_DISPLAY_MODE_ON = 0x13,
	//
	DISPLAY_INVERSION_OFF = 0x20,
	DISPLAY_INVERSION_ON = 0x21,
	GAMMA_SET = 0x26,
	DISPLAY_OFF = 0x28,
	DISPLAY_ON = 0x29,
	COLUMN_ADDRESS_SET = 0x2a,
	PAGE_ADDRESS_SET = 0x2b,
	MEMORY_WRITE = 0x2c,
	COLOR_SET = 0x2d,
	MEMORY_READ = 0x2e,
	//
	PARTIAL_AREA = 0x30,
	VERTICAL_SCROLLING_DEFINITION = 0x33,
	TEARING_EFFECT_LINE_OFF = 0x34,
	TEARING_EFFECT_LINE_ON = 0x35 ,
	MEMORY_ACCESS_CONTROL = 0x36,
	VERTICAL_SCROLLING_START_ADDRESS = 0x37,
	IDLE_MODE_OFF = 0x38,
	IDLE_MODE_ON = 0x39,
	PIXEL_FORMAT_SET = 0x3A,
	WRITE_MEMORY_CONTINUE = 0x3C,
	READ_MEMORY_CONTINUE = 0x3D,
	//
	RGB_INTERFACE_SIGNAL_CONTROL = 0xB0,
	FRAME_RATE_CONTROL = 0xB1,
	FRAME_RATE_CONTROL2 = 0xB2,
	FRAME_RATE_CONTROL3 = 0xB3,
	DISPLAY_INVERSION_CONTROL = 0xB4,
	BLANKING_PORCH_CONTROL = 0xB5,
	DISPLAY_FUNCTION_CONTROL = 0xB6,
	ENTRY_MODE_SET = 0xB7,
	BACKLIGHT_CONTROL1 = 0xB8,
	BACKLIGHT_CONTROL2 = 0xB9,
	BACKLIGHT_CONTROL3 = 0xBA,
	BACKLIGHT_CONTROL4 = 0xBB,
	BACKLIGHT_CONTROL5 = 0xBC,
	BACKLIGHT_CONTROL6 = 0xBD,
	BACKLIGHT_CONTROL7 = 0xBE,
	BACKLIGHT_CONTROL8 = 0xBF,
	//
	POWER_CONTROL1 = 0xC0,
	POWER_CONTROL2 = 0xC1,
	VCOM_CONTROL1 = 0xC5,
	VCOM_CONTROL2 = 0xC7,
	//
	READ_ID1 = 0xDA,
	READ_ID2 = 0xDB,
	READ_ID3 = 0xDC,
	//
	POSITIVE_GAMMA_CORRECTION = 0xE0,
	NEGATIVE_GAMMA_CORRECTION = 0xE1,
	INTERFACE_CONTROL = 0xF6,
	// extended
	POWER_CONTROL_A = 0xCB,
	POWER_CONTROL_B = 0xCF,
	DRIVER_TIMING_CONTROL_A = 0xE8,
	DRIVER_TIMING_CONTROL_b = 0xEA,
	POWER_ON_SEQUENCE_CONTROL = 0xED,
	PUMP_RATIO_CONTROL = 0xF7
} ili9341_command_t;

// MEMORY_ACCESS_CONTROL 0x0b
#define MY 7 // row address order 0=top to bottom, 1=bottom to top
#define MX 6 // column addres order 0=left to right, 1=right to left
#define MV 5 // row/column exchange
#define ML 4 // vertical refresh order
#define BGR 3 // rgb/grb order
#define MH 2 // horizontal refresh order
// DISPLAY_FUNCTION_CONTROL 0xB6
#define PT0 0
#define PT1 1
#define PTG0 2
#define PTG1 3
//
#define ISC0 0
#define ISC1 1
#define ISC2 2
#define ISC3 3
#define ISC 0b00001111
#define SM 4
#define SS 5
#define GS 6
#define REV 7
//
#define NL 0b00111111

static void cslow() {
  pin_reset(_cspin);
}

static void cshigh() {
  pin_set(_cspin);
}

static void dclow() {
  pin_reset(_dcpin);
}

static void dchigh() {
  pin_set(_dcpin);
}

static void transmit_command(ili9341_command_t cmd) {
	dclow();
	cslow();
	spi_transfer8(cmd);
	cshigh();
	dchigh();
}

static void transmit_data(uint8_t data) {
	dchigh();
	cslow();
	spi_transfer8(data);
	cshigh();
}

static void transmit_data16(uint16_t data) {
	dchigh();
	cslow();
	spi_transfer8((uint8_t)(data >> 8));
	spi_transfer8(data );
	cshigh();
}

static void command(uint8_t cmd) {
	transmit_command(cmd);
}

static void command1(uint8_t cmd, uint8_t p1) {
	transmit_command(cmd);
	transmit_data(p1);
}

static void command2(uint8_t cmd, uint8_t p1, uint8_t p2) {
	transmit_command(cmd);
	transmit_data(p1);
	transmit_data(p2);
}

static void command3(uint8_t cmd, uint8_t p1, uint8_t p2, uint8_t p3) {
	transmit_command(cmd);
	transmit_data(p1);
	transmit_data(p2);
	transmit_data(p3);
}

static void command4(uint8_t cmd, uint8_t p1, uint8_t p2, uint8_t p3, uint8_t p4) {
	transmit_command(cmd);
	transmit_data(p1);
	transmit_data(p2);
	transmit_data(p3);
	transmit_data(p4);
}

void ili9341_enable(pin_t cspin, pin_t dcpin) {
	_cspin = cspin;
	_dcpin = dcpin;
  pin_mode(_cspin, Output);
  pin_mode(_dcpin, Output);
	command(SOFTWARE_RESET);
	//_delay_ms(50);
	command(DISPLAY_OFF);
	command1(POWER_CONTROL1, 0x23); // 4.60v
	command1(POWER_CONTROL2, 0x10); // ???
	command2(VCOM_CONTROL1, 0x2B, 0x2B); // 3.775V
	command1(VCOM_CONTROL2, 0xC0); // no offset voltage
	command1(MEMORY_ACCESS_CONTROL, BIT(MX) | BIT(BGR));
	command2(VERTICAL_SCROLLING_START_ADDRESS, 0, 0);
	command1(PIXEL_FORMAT_SET, 0x55); // 16bit/px
	command2(FRAME_RATE_CONTROL, 0, 0x1B);
	command3(DISPLAY_FUNCTION_CONTROL, BIT(PTG1), BIT(REV) + 2, 0x27);
	// TODO: set gamma
	command(SLEEP_OUT);
	//_delay_ms(150);
	command(DISPLAY_ON);
	//_delay_ms(200);
}

void ili9341_disable() {
	command(DISPLAY_OFF);
	command(ENTER_SLEEP_MODE);
}

void ili9341_set_pixel(uint16_t x, uint16_t y, uint16_t color) {
	uint8_t xh = x >> 8, xl = x & 0xff;
	uint8_t yh = y >> 8, yl = y & 0xff;
	uint8_t ch = (uint16_t)color >> 8, cl = (uint16_t)(color & 0xff);
	command4(COLUMN_ADDRESS_SET, xh, xl, xh, xl);
	command4(PAGE_ADDRESS_SET, yh, yl, yh, yl);
	command(MEMORY_WRITE);
	transmit_data(ch);
	transmit_data(cl);
}


ili9341.c

#ifndef _ili9341_h
#define _ili9341_h
#include "gpio.h"
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif
void ili9341_enable(pin_t cspin, pin_t dcpin);
void ili9341_disable();
void ili9341_set_pixel(uint16_t x, uint16_t y, uint16_t color);
#ifdef __cplusplus
}
#endif
#endif


ili9341.h

#include <stm32f1xx.h>
#include "spi.h"

#define SPIGPIO GPIOA
#define SCK 5 // 3
#define MISO 6 // 4
#define MOSI 7 // 5

void spi_enable() {
	RCC->APB2ENR |= RCC_APB2ENR_IOPAEN // port clock
			| RCC_APB2ENR_AFIOEN // alt function clock
			| RCC_APB2ENR_SPI1EN; //	spi clock
	GPIOA->CRL &= 0x000FFFFF;
	GPIOA->CRL |= 0xD4D00000; // pb6 input/float, pb7 & pb5 output/alt-func open-drain
	SPI1->CR1 = SPI_CR1_SSM | SPI_CR1_SSI // software slave select
			| SPI_CR1_MSTR | SPI_CR1_SPE // spi master
			| (5 << SPI_CR1_BR_Pos); // baudrate
	AFIO->MAPR &= ~AFIO_MAPR_SPI1_REMAP;
}

void spi_disable() {
	SPI1->CR1 = 0;
	RCC->APB2ENR &= ~RCC_APB2ENR_SPI1EN;
}

uint8_t spi_transfer8(uint8_t data) {
	SPI1->DR = data;
	while (!(SPI1->SR & SPI_SR_RXNE));
	return SPI1->DR;
}

void spi_transfer(uint8_t * data, uint8_t len) {
	uint8_t *p = data;
	SPI1->DR = *p;
	while (--len > 0) {
		uint8_t out = *(p + 1);
		while (!(SPI1->SR & SPI_SR_RXNE));
		uint8_t in = SPI1->DR;
		while (!(SPI1->SR & SPI_SR_TXE));
		SPI1->DR = out;
		*p++ = in;
	}
}


spi.c

#ifndef _spi_h_
#define _spi_h_
#include <stdint.h>
#include <stdbool.h>

#ifdef __cplusplus
extern "C" {
#endif
void spi_enable();
void spi_disable();
uint8_t spi_transfer8(uint8_t data);
void spi_transfer(uint8_t * data, uint8_t len);
#ifdef __cplusplus
}
#endif
#endif


spi.h

#include <stm32f1xx.h>
#include "system.h"
#include <stdint.h>

static volatile uint32_t _system_ticks;

void SysTick_Handler() {
	_system_ticks++;
}

uint32_t system_ms() {
	__disable_irq();
	uint32_t v = _system_ticks;
	__enable_irq();
	return v;
}

void system_init(void) {
	FLASH->ACR &=~FLASH_ACR_LATENCY_0; // latency 2 wait states
	FLASH->ACR |= FLASH_ACR_LATENCY_1;
	RCC->CR |= RCC_CR_HSEON; // enable hse
	while (!(RCC->CR & RCC_CR_HSERDY));
	RCC->CFGR |= RCC_CFGR_PLLSRC // HSE as PLL input
		| RCC_CFGR_PPRE1_DIV2 // APB1 prescale 2 (<36MHz)
		| RCC_CFGR_PLLMULL9; // clk = 8 * 9 = 72Mhz
	RCC->CR |= RCC_CR_PLLON;
	while (!(RCC->CR & RCC_CR_PLLRDY));
	RCC->CFGR |= RCC_CFGR_SW_PLL; // PLL as system clock source*/
	SystemCoreClockUpdate();
	SysTick_Config((SystemCoreClock / 1000));
	__enable_irq();
}

int main() {
	system_init();
	setup();
	while (1)
		loop();
}


system.c

#ifndef _system_h
#define _system_h
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif
uint32_t system_ms();
void setup();
void loop();
#ifdef __cplusplus
}
#endif
#endif


system.h

#include <stm32f1xx.h>
#include "uart.h"

static uint8_t tx_buffer[UART_TX_BUFFER_SIZE + 1];
static uint8_t tx_head;
static uint8_t tx_tail;

static uart_handler_t _handler;

void _uart_enable(uint32_t baudrate, bool enable_tx, bool enable_rx) {
	RCC->APB1ENR |= RCC_APB1ENR_USART2EN;
	RCC->APB2ENR |= RCC_APB2ENR_IOPAEN; // port A
	// pins a2 and a3 for usart2
	GPIOA->CRL &= (GPIO_CRL_MODE2 | GPIO_CRL_CNF2 | GPIO_CRL_MODE3 | GPIO_CRL_CNF3);
	GPIOA->CRL |= ((0x1 << GPIO_CRL_MODE2_Pos) | (0x2 << GPIO_CRL_CNF2_Pos) |
		(0x0 << GPIO_CRL_MODE3_Pos) | (0x2 << GPIO_CRL_CNF3_Pos));
	// baudrate
	uint16_t uartdiv = SystemCoreClock / baudrate;
	USART2->BRR = (((uartdiv / 16) << USART_BRR_DIV_Mantissa_Pos) |
			((uartdiv % 16) << USART_BRR_DIV_Fraction_Pos));
	USART2->CR1 |= USART_CR1_UE;
	if (enable_tx)
		USART2->CR1 |= USART_CR1_TE;
	if (enable_rx)
		USART2->CR1 |= USART_CR1_RE | USART_CR1_RXNEIE;
	NVIC_EnableIRQ(USART2_IRQn);
}

void uart_enable(uint32_t baudrate, uart_handler_t handler) {
	_handler = handler;
	_uart_enable(baudrate, true, true);
}

void uart_enable_tx_only(uint32_t baudrate) {
	_uart_enable(baudrate, true, false);
}

void uart_enable_rx_only(uint32_t baudrate, uart_handler_t handler) {
	_handler = handler;
	_uart_enable(baudrate, false, true);
}

void uart_disable() {
	NVIC_DisableIRQ(USART2_IRQn);
	USART2->CR1 &= 0;
	RCC->APB1ENR &= ~RCC_APB1ENR_USART2EN;
	GPIOA->CRL &= GPIO_CRL_MODE2 | GPIO_CRL_CNF2 | GPIO_CRL_MODE3 | GPIO_CRL_CNF3;
}

bool uart_tx_buffer_is_empty() {
	uint8_t next = (tx_head < UART_TX_BUFFER_SIZE ? tx_head + 1 : 0);
	return tx_tail != next;
}

void uart_write(uint8_t * data, uint8_t len) {
	bool empty = (tx_head == tx_tail);
	for (int i = 0; i < len; i++) {
		tx_buffer[tx_head] = data[i];
		tx_head = (tx_head < UART_TX_BUFFER_SIZE ? tx_head + 1 : 0);
	}
	if (empty)
		USART2->CR1 |= USART_CR1_TXEIE;
}

void uart_print(uint8_t * data) {
	uart_write(data, strlen((char *)data));
}

void USART2_IRQHandler(void) {
	if (USART2->SR & USART_SR_RXNE) {
		if (_handler)
			_handler(USART2->DR);
	}
	if (USART2->SR & USART_SR_TXE) {
		if (tx_head != tx_tail) {
			USART2->DR = tx_buffer[tx_tail];
			tx_tail = (tx_tail < UART_TX_BUFFER_SIZE ? tx_tail + 1 : 0);
		} else
			USART2->CR1 &= ~USART_CR1_TXEIE;
	}
}


uart.c

#ifndef _uart_h
#define _uart_h
#include <stdint.h>
#include <stdbool.h>

#if !defined(UART_TX_BUFFER_SIZE)
#define UART_TX_BUFFER_SIZE 50
#endif

typedef void(*uart_handler_t)(uint8_t);

#ifdef __cplusplus
extern "C" {
#endif
void uart_enable(uint32_t bitrate, uart_handler_t handler);
void uart_enable_tx_only(uint32_t bitrate);
void uart_enable_rx_only(uint32_t bitrate, uart_handler_t handler);
void uart_disable();
bool uart_tx_buffer_is_empty();
void uart_write(uint8_t * data, uint8_t len);
void uart_print(uint8_t * str);
#ifdef __cplusplus
}
#endif
#endif


uart.h

#include "system.h"
#include "gpio.h"
#include "spi.h"
#include "ili9341.h"
#include "uart.h"
#include <stdio.h>

uint32_t stamp;
uint8_t buf[10];

void uart_handler(uint8_t ch) {
  sprintf((char *)buf, "ch: %d\n", ch);
  uart_print(buf);
}

void setup() {
  port_enable(pin_port(PinC13));
  pin_mode(PinC13, Output);
  pin_reset(PinC13);

  spi_enable();
  port_enable(PortB);
  ili9341_enable(PinB8, PinB9);
  ili9341_set_pixel(0, 0, 0xffff);
  uart_enable(9600, uart_handler);
}

void loop() {
  uint32_t now = system_ms();
	if (now % 1000 < stamp % 1000) {
  	sprintf((char *)buf, "%ld\n", now);
		uart_print(buf);
    uart_handler(now / 1000);
	}
	stamp = now;
  if (now  % 1000 < 500)
    pin_set(PinC13);
  else
    pin_reset(PinC13);
}
