TM1637Display.cpp

//  Author: avishorp@gmail.com
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//
//  This library 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
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

extern "C" {
	#include <stdlib.h>
	#include <string.h>
	#include <inttypes.h>
}

#include <TM1637Display.h>
#include <Arduino.h>

#define TM1637_I2C_COMM1    0x40
#define TM1637_I2C_COMM2    0xC0
#define TM1637_I2C_COMM3    0x80

//
//      A
//     ---
//  F |   | B
//     -G-
//  E |   | C
//     ---
//      D
const uint8_t digitToSegment[] = {
	// XGFEDCBA
	0b00111111,    // 0
	0b00000110,    // 1
	0b01011011,    // 2
	0b01001111,    // 3
	0b01100110,    // 4
	0b01101101,    // 5
	0b01111101,    // 6
	0b00000111,    // 7
	0b01111111,    // 8
	0b01101111,    // 9
	0b01110111,    // A
	0b01111100,    // b
	0b00111001,    // C
	0b01011110,    // d
	0b01111001,    // E
	0b01110001     // F
};

static const uint8_t minusSegments = 0b01000000;

TM1637Display::TM1637Display(uint8_t pinClk, uint8_t pinDIO, unsigned int bitDelay)
{
	// Copy the pin numbers
	m_pinClk = pinClk;
	m_pinDIO = pinDIO;
	m_bitDelay = bitDelay;

	// Set the pin direction and default value.
	// Both pins are set as inputs, allowing the pull-up resistors to pull them up
	pinMode(m_pinClk, INPUT);
	pinMode(m_pinDIO, INPUT);
	digitalWrite(m_pinClk, LOW);
	digitalWrite(m_pinDIO, LOW);
}

void TM1637Display::setBrightness(uint8_t brightness, bool on)
{
	m_brightness = (brightness & 0x7) | (on? 0x08 : 0x00);
}

void TM1637Display::setSegments(const uint8_t segments[], uint8_t length, uint8_t pos)
{
	// Write COMM1
	start();
	writeByte(TM1637_I2C_COMM1);
	stop();

	// Write COMM2 + first digit address
	start();
	writeByte(TM1637_I2C_COMM2 + (pos & 0x03));

	// Write the data bytes
	for (uint8_t k=0; k < length; k++)
		writeByte(segments[k]);

	stop();

	// Write COMM3 + brightness
	start();
	writeByte(TM1637_I2C_COMM3 + (m_brightness & 0x0f));
	stop();
}

void TM1637Display::clear()
{
	uint8_t data[] = { 0, 0, 0, 0 };
	setSegments(data);
}

void TM1637Display::showNumberDec(int num, bool leading_zero, uint8_t length, uint8_t pos)
{
	showNumberDecEx(num, 0, leading_zero, length, pos);
}

void TM1637Display::showNumberDecEx(int num, uint8_t dots, bool leading_zero,
                                    uint8_t length, uint8_t pos)
{
	showNumberBaseEx(num < 0? -10 : 10, num < 0? -num : num, dots, leading_zero, length, pos);
}

void TM1637Display::showNumberHexEx(uint16_t num, uint8_t dots, bool leading_zero,
                                    uint8_t length, uint8_t pos)
{
	showNumberBaseEx(16, num, dots, leading_zero, length, pos);
}

void TM1637Display::showNumberBaseEx(int8_t base, uint16_t num, uint8_t dots, bool leading_zero,
                                    uint8_t length, uint8_t pos)
{
	bool negative = false;

	if (base < 0) {
		base = -base;
		negative = true;
	}

	uint8_t digits[4];

	if (num == 0 && !leading_zero) {
		// Singular case - take care separately
		for (uint8_t i = 0; i < (length-1); i++)
			digits[i] = 0;
		digits[length-1] = encodeDigit(0);
	}
	else {
		// uint8_t i = length-1;
		// if (negative) {
		// 	// Negative number, show the minus sign
		// 	digits[i] = minusSegments;
		// 	i--;
		// }

		for (int i = length-1; i >= 0; --i)
		{
			uint8_t digit = num % base;

			if (digit == 0 && num == 0 && leading_zero == false)
				// Leading zero is blank
				digits[i] = 0;
			else
				digits[i] = encodeDigit(digit);

			if (digit == 0 && num == 0 && negative) {
				digits[i] = minusSegments;
				negative = false;
			}

			num /= base;
		}
	}

	if (dots != 0)
	{
		showDots(dots, digits);
	}

	setSegments(digits, length, pos);
}

void TM1637Display::bitDelay()
{
	delayMicroseconds(m_bitDelay);
}

void TM1637Display::start()
{
	pinMode(m_pinDIO, OUTPUT);
	bitDelay();
}

void TM1637Display::stop()
{
	pinMode(m_pinDIO, OUTPUT);
	bitDelay();
	pinMode(m_pinClk, INPUT);
	bitDelay();
	pinMode(m_pinDIO, INPUT);
	bitDelay();
}

bool TM1637Display::writeByte(uint8_t b)
{
	uint8_t data = b;

	// 8 Data Bits
	for(uint8_t i = 0; i < 8; i++) {
		// CLK low
		pinMode(m_pinClk, OUTPUT);
		bitDelay();

		// Set data bit
		if (data & 0x01)
			pinMode(m_pinDIO, INPUT);
		else
			pinMode(m_pinDIO, OUTPUT);

		bitDelay();

		// CLK high
		pinMode(m_pinClk, INPUT);
		bitDelay();
		data = data >> 1;
	}

	// Wait for acknowledge
	// CLK to zero
	pinMode(m_pinClk, OUTPUT);
	pinMode(m_pinDIO, INPUT);
	bitDelay();

	// CLK to high
	pinMode(m_pinClk, INPUT);
	bitDelay();
	uint8_t ack = digitalRead(m_pinDIO);
	if (ack == 0)
		pinMode(m_pinDIO, OUTPUT);

	bitDelay();
	pinMode(m_pinClk, OUTPUT);
	bitDelay();

	return ack;
}

void TM1637Display::showDots(uint8_t dots, uint8_t* digits)
{
	for (int i = 0; i < 4; ++i)
	{
		digits[i] |= (dots & 0x80);
		dots <<= 1;
	}
}

uint8_t TM1637Display::encodeDigit(uint8_t digit)
{
	return digitToSegment[digit & 0x0f];
}