/* This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
/** library to communicate with a Titan Micro TM1637 IC attached to a 7-segment displays (code)
 *  @file led_tm1637.c
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @date 2017
 *  @note peripherals used: GPIO @ref led_tm1637_gpio, timer @ref led_tm1637_timer
 *  @note only 4-digit 7-segment displays are considered as this is the most common case
 *  @warning all calls are blocking
 *  @note the protocol is very similar to I2C but incompatible for the following reasons: the pin capacitance is too large for open-drain type output with weak pull-up resistors (push-pull needs to be used, preventing to get ACKs since no indication of the ACK timing is provided); the devices doesn't use addresses; the STM32 I2C will switch to receiver mode when the first sent byte (the I2C address) has last bit set to 1 (such as for address commands with B7=1 where B7 is transmitted last), preventing to send further bytes (the data byte after the address)
 *
 *  bit vs segment: 0bpgfedcba
 *  +a+
 *  f b p
 *  +g+
 *  e c p
 *  +d+
 */

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdlib.h> // memory utilities
#include <string.h> // string utilities

/* STM32 (including CM3) libraries */
#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/stm32/timer.h> // timer library

#include "global.h" // global utilities
#include "led_tm1637.h" // TM1637 header and definitions

/** @defgroup led_tm1637_gpio GPIO used to communication with TM1637 IC
 *  @{
 */
#define LED_TM1637_CLK_PORT B /**< port for CLK signal */
#define LED_TM1637_CLK_PIN 6 /**< pin for CLK signal */
#define LED_TM1637_DIO_PORT B /**< port for DIO signal */
#define LED_TM1637_DIO_PIN 7 /**< pin for DIO signal */
/** @} */

/** @defgroup led_tm1637_timer timer used to communication with TM1637 IC
 *  @{
 */
#define LED_TM1637_TIMER 3 /**< timer to create signal */
/** @} */

/** display brightness */
enum led_tm1637_brightness_t display_brightness = LED_TM1637_14DIV16;

/** ASCII characters encoded for the 7 segments digit block
 *  @note starts with space
 */
static const uint8_t ascii_7segments[] = {
	0x00, // 0b00000000 space
	0x30, // 0b00110000 ! (I)
	0x22, // 0b00100010 "
	0x5c, // 0b01011100 # (o)
	0x6d, // 0b01101101 $ (s)
	0x52, // 0b01010010 % (/)
	0x7d, // 0b01111101 & (6)
	0x20, // 0b00100000 '
	0x39, // 0b00111001 ( ([)
	0x0f, // 0b00001111 )
	0x70, // 0b01110000 *
	0x46, // 0b01000110 +
	0x10, // 0b00010000 ,
	0x40, // 0b01000000 -
	0x10, // 0b00010000 . (,)
	0x52, // 0b01010010 /
	0x3f, // 0b00111111 0
	0x06, // 0b00000110 1
	0x5b, // 0b01011011 2
	0x4f, // 0b01001111 3
	0x66, // 0b01100110 4
	0x6d, // 0b01101101 5
	0x7d, // 0b01111101 6
	0x07, // 0b00000111 7
	0x7f, // 0b01111111 8
	0x6f, // 0b01101111 9
	0x48, // 0b01001000 : (=)
	0x48, // 0b01001000 ; (=)
	0x58, // 0b01011000 <
	0x48, // 0b01001000 =
	0x4c, // 0b01001100 >
	0x53, // 0b01010011 ?
	0x7b, // 0b01111011 @
	0x77, // 0b01110111 A
	0x7f, // 0b01111111 B
	0x39, // 0b00111001 C
	0x5e, // 0b01011110 D
	0x79, // 0b01111001 E
	0x71, // 0b01110001 F
	0x3d, // 0b00111101 G
	0x76, // 0b01110110 H
	0x30, // 0b00110000 I
	0x1e, // 0b00011110 J
	0x76, // 0b01110110 K
	0x38, // 0b00111000 L
	0x37, // 0b00110111 M
	0x37, // 0b00110111 N
	0x3f, // 0b00111111 O
	0x73, // 0b01110011 P
	0x6b, // 0b01101011 Q
	0x33, // 0b00110011 R
	0x6d, // 0b01101101 S
	0x78, // 0b01111000 T
	0x3e, // 0b00111110 U
	0x3e, // 0b00111110 V (U)
	0x3e, // 0b00111110 W (U)
	0x76, // 0b01110110 X (H)
	0x6e, // 0b01101110 Y
	0x5b, // 0b01011011 Z
	0x39, // 0b00111001 [
	0x64, // 0b01100100 '\'
	0x0f, // 0b00001111 /
	0x23, // 0b00100011 ^
	0x08, // 0b00001000 _
	0x02, // 0b00000010 `
	0x5f, // 0b01011111 a
	0x7c, // 0b01111100 b
	0x58, // 0b01011000 c
	0x5e, // 0b01011110 d
	0x7b, // 0b01111011 e
	0x71, // 0b01110001 f
	0x6f, // 0b01101111 g
	0x74, // 0b01110100 h
	0x10, // 0b00010000 i
	0x0c, // 0b00001100 j
	0x76, // 0b01110110 k
	0x30, // 0b00110000 l
	0x54, // 0b01010100 m
	0x54, // 0b01010100 n
	0x5c, // 0b01011100 o
	0x73, // 0b01110011 p
	0x67, // 0b01100111 q
	0x50, // 0b01010000 r
	0x6d, // 0b01101101 s
	0x78, // 0b01111000 t
	0x1c, // 0b00011100 u
	0x1c, // 0b00011100 v (u)
	0x1c, // 0b00011100 w (u)
	0x76, // 0b01110110 x
	0x6e, // 0b01101110 y
	0x5b, // 0b01011011 z
	0x39, // 0b00111001 { ([)
	0x30, // 0b00110000 |
	0x0f, // 0b00001111 } ([)
	0x40, // 0b01000000 ~
};

void led_tm1637_setup(void)
{
	// configure GPIO for CLK and DIO signals
	rcc_periph_clock_enable(RCC_GPIO(LED_TM1637_CLK_PORT)); // enable clock for GPIO peripheral
	gpio_set(GPIO(LED_TM1637_CLK_PORT), GPIO(LED_TM1637_CLK_PIN)); // idle high
	gpio_set_mode(GPIO(LED_TM1637_CLK_PORT), GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(LED_TM1637_CLK_PIN)); // master start the communication (capacitance is to large for open drain), only switch to input for ack from slave
	rcc_periph_clock_enable(RCC_GPIO(LED_TM1637_DIO_PORT)); // enable clock for GPIO peripheral
	gpio_set(GPIO(LED_TM1637_DIO_PORT), GPIO(LED_TM1637_DIO_PIN)); // idle high
	gpio_set_mode(GPIO(LED_TM1637_DIO_PORT), GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(LED_TM1637_DIO_PIN)); // master start the communication (capacitance is to large for open drain), only switch to input for ack from slave
	// first clock then data high also stands for stop condition

	// setup timer to create signal timing (each tick is used for a single GPIO transition)
	rcc_periph_clock_enable(RCC_TIM(LED_TM1637_TIMER)); // enable clock for timer block
	timer_reset(TIM(LED_TM1637_TIMER)); // reset timer state
	timer_set_mode(TIM(LED_TM1637_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock, edge alignment (simple count), and count up
	timer_set_prescaler(TIM(LED_TM1637_TIMER), 0); // don't prescale to get most precise timing ( 1/(72E6/1/(2**16))=0.91 ms > 0.5 us )
	timer_set_period(TIM(LED_TM1637_TIMER), 500); // set the clock frequency (500 kHz is the maximum per datasheet, but also because of the bit banging implementation)
	timer_clear_flag(TIM(LED_TM1637_TIMER), TIM_SR_UIF); // clear flag
	timer_update_on_overflow(TIM(LED_TM1637_TIMER)); // only use counter overflow as UEV source (use overflow as start time or timeout)
}

/** wait until clock tick (timer overflow) occurred
 */
static inline void led_tm1637_tick(void)
{
	while (!timer_get_flag(TIM(LED_TM1637_TIMER), TIM_SR_UIF)); // wait until counter overflow update event happens
	timer_clear_flag(TIM(LED_TM1637_TIMER), TIM_SR_UIF); // clear event flag
}

/** write data on bus
 *  @param[in] data bytes to write
 *  @param[in] length number of bytes to write
 *  @return if write succeeded
 *  @note includes start and stop conditions
 */
static bool led_tm1637_write(const uint8_t* data, uint8_t length)
{
	bool to_return = true; // return if write succeeded
	if (NULL==data || 0==length) { // verify there it data to be read
		return false;
	}

	// enable timer for signal generation
	timer_set_counter(TIM(LED_TM1637_TIMER), 0); // reset timer counter
	timer_enable_counter(TIM(LED_TM1637_TIMER)); // enable timer to generate timing
	led_tm1637_tick(); // wait to enforce minimum time since last write

	// send start condition (DIO then CLK low)
	gpio_set_mode(GPIO(LED_TM1637_DIO_PORT), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(LED_TM1637_DIO_PIN)); // ensure we can output to sent start condition
	gpio_clear(GPIO(LED_TM1637_DIO_PORT), GPIO(LED_TM1637_DIO_PIN)); // put DIO low
	led_tm1637_tick(); // wait for next tick
	gpio_clear(GPIO(LED_TM1637_CLK_PORT), GPIO(LED_TM1637_CLK_PIN)); // put CLK low

	// send data bytes (MSb first)
	for (uint8_t i=0; i<length; i++) { // send all bytes
		uint8_t byte = data[i];
		for (uint8_t b=0; b<8; b++) { // send all bits
			if (byte&0x1) { // send a 1
				gpio_set(GPIO(LED_TM1637_DIO_PORT), GPIO(LED_TM1637_DIO_PIN)); // put DIO high
			} else {
				gpio_clear(GPIO(LED_TM1637_DIO_PORT), GPIO(LED_TM1637_DIO_PIN)); // put DIO low
			}
			byte >>= 1; // shift data
			led_tm1637_tick(); // wait for next tick
			gpio_set(GPIO(LED_TM1637_CLK_PORT), GPIO(LED_TM1637_CLK_PIN)); // put CLK high
			led_tm1637_tick(); // wait for next tick (no DIO transition when CLK is high)
			gpio_clear(GPIO(LED_TM1637_CLK_PORT), GPIO(LED_TM1637_CLK_PIN)); // put CLK low
		}
		gpio_set_mode(GPIO(LED_TM1637_DIO_PORT), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO(LED_TM1637_DIO_PIN)); // switch DIO as input to read ACK
		led_tm1637_tick(); // wait for next tick (when the slave should ACK)
		gpio_set(GPIO(LED_TM1637_CLK_PORT), GPIO(LED_TM1637_CLK_PIN)); // put CLK high
		if (gpio_get(GPIO(LED_TM1637_DIO_PORT), GPIO(LED_TM1637_DIO_PIN))) { // no ACK received
			to_return = false; // remember there was an error
			break; // stop sending bytes
		}
		led_tm1637_tick(); // wait for next tick
		gpio_clear(GPIO(LED_TM1637_CLK_PORT), GPIO(LED_TM1637_CLK_PIN)); // put CLK low
		gpio_set_mode(GPIO(LED_TM1637_DIO_PORT), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(LED_TM1637_DIO_PIN)); // switch DIO back to output
	}

	// send stop condition
	led_tm1637_tick(); // wait for next tick
	gpio_set(GPIO(LED_TM1637_CLK_PORT), GPIO(LED_TM1637_CLK_PIN)); // put CLK high
	led_tm1637_tick(); // wait for next tick
	gpio_set(GPIO(LED_TM1637_DIO_PORT), GPIO(LED_TM1637_DIO_PIN)); // put DIO high
	timer_disable_counter(TIM(LED_TM1637_TIMER)); // stop timer since it's not used anymore

	return to_return;
}

/** write commands on bus to send data
 *  @param[in] address_command data data to send (including address as first byte)
 *  @param[in] length length of data
 *  @return if send succeeded
 */
static bool led_tm1637_send_data(uint8_t* address_command, uint8_t length)
{
	// sanity check
	if (0==length && NULL==address_command) {
		return false;
	}

	uint8_t data_command[] = { 0x40 }; // data command: write data, automatic address adding, normal
	uint8_t display_command[] = { 0x88+(display_brightness&0x0f) }; // display command: turn display on and set brightness
	
	if (led_tm1637_write(data_command, LENGTH(data_command)) && led_tm1637_write(address_command, length) && led_tm1637_write(display_command, LENGTH(display_command))) { // send commands
		return true;
	}
	return false;
}

bool led_tm1637_off(void)
{
	// note: while the TM1637 could recognize the display command thanks to the first two bits, we still need to send the data and address command first
	uint8_t data_command[] = { 0x40 }; // data command: write data, automatic address adding, normal
	uint8_t address_command[] = { 0xc0, 0x00, 0x00, 0x00, 0x00 }; // address command: clear all (if bit 7 of byte 4 is set switching off doesn't work correctly, I don't know why)
	uint8_t display_command[] = { 0x80 }; // display command: turn display off (we don't care about the brightness since it's set when turned on)
	
	if (led_tm1637_write(data_command,LENGTH(data_command)) && led_tm1637_write(address_command, LENGTH(address_command)) && led_tm1637_write(display_command, LENGTH(display_command))) { // send commands
		return true;
	}
	return false;
}

void led_tm1637_brightness(enum led_tm1637_brightness_t brightness)
{
	display_brightness = (brightness&0x0f); // save brightness
}

bool led_tm1637_number(uint16_t number)
{
	uint8_t data[] = { 0xc0, ascii_7segments[((number/1000)%10)+'0'-' '], ascii_7segments[((number/100)%10)+'0'-' '], ascii_7segments[((number/10)%10)+'0'-' '], ascii_7segments[((number/1)%10)+'0'-' '] }; // encode number on 4 digits
	return led_tm1637_send_data(data, LENGTH(data)); // transmit data
}

bool led_tm1637_time(uint8_t hours, uint8_t minutes)
{
	uint8_t data[] = { 0xc0, ascii_7segments[((hours/10)%10)+'0'-' '], ascii_7segments[((hours/1)%10)+'0'-' ']|0x80, ascii_7segments[((minutes/10)%10)+'0'-' '], ascii_7segments[((minutes/1)%10)+'0'-' '] }; // encode time on 4 digits
	return led_tm1637_send_data(data, LENGTH(data)); // transmit data
}

bool led_tm1637_text(char* text)
{
	if (strlen(text)!=4) { // input text should have exactly 4 characters
		return false;
	}
	for (uint8_t i=0; i<4; i++) { // input text should only contain printable character (8th bit is used for dots)
		if ((text[i]&0x7f)<' ' || (text[i]&0x7f)>=' '+LENGTH(ascii_7segments)) {
			return false;
		}
	}
	uint8_t data[] = { 0xc0, ascii_7segments[(text[0]&0x7f)-' ']|(text[0]&0x80), ascii_7segments[(text[1]&0x7f)-' ']|(text[1]&0x80), ascii_7segments[(text[2]&0x7f)-' ']|(text[2]&0x80), ascii_7segments[(text[3]&0x7f)-' ']|(text[3]&0x80) }; // encode text on 7 digits
	return led_tm1637_send_data(data, LENGTH(data)); // transmit data
}