dsPIC30F2010 I2C PCF8574T HD44780 LCD

Introduction

In previous post, I use the PCF8574AP DIP-16 chip to expand the output of dsPIC30F2010. Since this chip is an 8-bit bi-directional I/O device, it can be used to connect to any I/O peripheral devices. even an HD44780 character LCD. 

 

Test Program

A character LCD module comes with a PCF8574T is very popular and low cost. It is commonly an Arduino LCD module widely used among the students and electronic hobbyists. There are a lot of Arduino programming examples for this stuffs. 

 

dsPIC30F2010 Simple I2C LCD using PCF8574T 

Controlling an HD44780 character LCD via a PCF8574T is very easy with some additional code to process the 4-bit data transfer mode of the LCD chip controller. In this example, the I2C master micro-controller send some character to a 16x2 character LCD via a PCF8574T chip. 

Schematic:

Schematic

 This post show a full I2C devices interfacing examples using an ATMega644P AVR chip.

MikroC Source Code:

1. 
   
2. const char PCF8574_W=0x40;
3. const char PCF8574_R=0x41;
4. const char PCF8574T_LCD_W=0x4E;
5. const char PCF8574T_LCD_R=0x4F;
6. const char PCF8574A_W=0x70;
7. const char PCF8574A_R=0x71;
8. 
   
9. void pcf8574_write(char _data){
10. I2C1_Start(); // issue I2C start signal
11. I2C1_Write(PCF8574T_LCD_W); // send byte via I2C (device address + W)
12. I2C1_Write(_data); // send byte (data address)
13. I2C1_Stop(); // issue I2C stop signal
14. }
15. 
    
16. /*TWI LCD Driver*/
17. #define RS 0
18. #define RW 1
19. #define EN 2
20. #define BL 3
21. 
    
22. #define i2c_lcd_cursor_off() i2c_lcd_command(0x0C)
23. #define i2c_lcd_line_1() i2c_lcd_command(0x80)
24. #define i2c_lcd_line_2() i2c_lcd_command(0xC0)
25. 
    
26. char backLight=1;
27. 
    
28. void i2c_lcd_command(char command){
29. char _data;
30. _data=command&0xF0;
31. pcf8574_write(_data|(backLight<<BL)|(1<<EN));
32. //_delay_us(10);
33. pcf8574_write(_data|(backLight<<BL));
34. //_delay_us(50);
35. 
    
36. _data=command<<4;
37. pcf8574_write(_data|(backLight<<BL)|(1<<EN));
38. //_delay_us(10);
39. pcf8574_write(_data|(backLight<<BL));
40. //_delay_us(50);
41. }
42. 
    
43. void i2c_lcd__data(char command){
44. char _data;
45. _data=command&0xF0;
46. pcf8574_write(_data|(backLight<<BL)|(1<<EN)|(1<<RS));
47. //_delay_us(10);
48. pcf8574_write(_data|(backLight<<BL)|(1<<RS));
49. Delay_us(50);
50. 
    
51. _data=command<<4;
52. pcf8574_write(_data|(backLight<<BL)|(1<<EN)|(1<<RS));
53. //Delay_us(10);
54. pcf8574_write(_data|(backLight<<BL)|(1<<RS));
55. //Delay_us(50);
56. }
57. 
    
58. void i2c_lcd_xy(char x, char y){
59. char addr[]={0x80,0xC0};
60. i2c_lcd_command(addr[y-1]+x-1);
61. }
62. 
    
63. void i2c_lcd_text(char *txt){
64. while(*txt) i2c_lcd__data(*txt++);
65. }
66. 
    
67. void i2c_lcd_clear(void){
68. i2c_lcd_command(0x01);
69. Delay_ms(5);
70. }
71. 
    
72. void i2c_lcd_init(void){
73. pcf8574_write(0);
74. Delay_ms(10);
75. i2c_lcd_command(0x33);
76. Delay_us(10);
77. i2c_lcd_command(0x32);
78. Delay_us(10);
79. i2c_lcd_command(0x28);
80. Delay_us(10);
81. i2c_lcd_command(0x0F);
82. Delay_us(10);
83. i2c_lcd_command(0x01);
84. Delay_ms(10);
85. i2c_lcd_command(0x06);
86. Delay_us(10);
87. }
88. 
    
89. void main(){
90. char temp = 0, i = 0;
91. I2C1_Init(10000); // initialize I2C communication
92. Delay_ms(10);
93. i2c_lcd_init();
94. Delay_ms(10);
95. i2c_lcd_text("dsPIC30F2010 I2C");
96. i2c_lcd_line_2();
97. i2c_lcd_text("PCF8574T LCD");
98. i2c_lcd_cursor_off();
99. 
    
100. while(1){
101. 
     
102. }
103. }

I test this example on my DIY dsPIC30F2010 Prototype Board. It works fine.

 

My DIY dsPIC30F2010 Prototype Board

dsPIC30F2010 5V DVM I2C LCD using PCF8574T 

There is one on-board POT. So I made a simple 5VDC Digital Volt Meter with this I2C LCD. The schematic remains the same a above.

 

Test Program

 

MikroC Source Code:

1. 
   
2. const char PCF8574_W=0x40;
3. const char PCF8574_R=0x41;
4. const char PCF8574T_LCD_W=0x4E;
5. const char PCF8574T_LCD_R=0x4F;
6. const char PCF8574A_W=0x70;
7. const char PCF8574A_R=0x71;
8. 
   
9. void pcf8574_write(char _data){
10. I2C1_Start(); // issue I2C start signal
11. I2C1_Write(PCF8574T_LCD_W); // send byte via I2C (device address + W)
12. I2C1_Write(_data); // send byte (data address)
13. I2C1_Stop(); // issue I2C stop signal
14. }
15. 
    
16. /*TWI LCD Driver*/
17. #define RS 0
18. #define RW 1
19. #define EN 2
20. #define BL 3
21. 
    
22. #define i2c_lcd_cursor_off() i2c_lcd_command(0x0C)
23. #define i2c_lcd_line_1() i2c_lcd_command(0x80)
24. #define i2c_lcd_line_2() i2c_lcd_command(0xC0)
25. 
    
26. char backLight=1;
27. 
    
28. void i2c_lcd_command(char command){
29. char _data;
30. _data=command&0xF0;
31. pcf8574_write(_data|(backLight<<BL)|(1<<EN));
32. //_delay_us(10);
33. pcf8574_write(_data|(backLight<<BL));
34. //_delay_us(50);
35. 
    
36. _data=command<<4;
37. pcf8574_write(_data|(backLight<<BL)|(1<<EN));
38. //_delay_us(10);
39. pcf8574_write(_data|(backLight<<BL));
40. //_delay_us(50);
41. }
42. 
    
43. void i2c_lcd__data(char command){
44. char _data;
45. _data=command&0xF0;
46. pcf8574_write(_data|(backLight<<BL)|(1<<EN)|(1<<RS));
47. //_delay_us(10);
48. pcf8574_write(_data|(backLight<<BL)|(1<<RS));
49. Delay_us(50);
50. 
    
51. _data=command<<4;
52. pcf8574_write(_data|(backLight<<BL)|(1<<EN)|(1<<RS));
53. //Delay_us(10);
54. pcf8574_write(_data|(backLight<<BL)|(1<<RS));
55. //Delay_us(50);
56. }
57. 
    
58. void i2c_lcd_xy(char x, char y){
59. char addr[]={0x80,0xC0};
60. i2c_lcd_command(addr[y-1]+x-1);
61. }
62. 
    
63. void i2c_lcd_text(char *txt){
64. while(*txt) i2c_lcd__data(*txt++);
65. }
66. 
    
67. void i2c_lcd_clear(void){
68. i2c_lcd_command(0x01);
69. Delay_ms(10);
70. }
71. 
    
72. void i2c_lcd_init(void){
73. pcf8574_write(0);
74. Delay_ms(10);
75. i2c_lcd_command(0x33);
76. Delay_us(10);
77. i2c_lcd_command(0x32);
78. Delay_us(10);
79. i2c_lcd_command(0x28);
80. Delay_us(10);
81. i2c_lcd_command(0x0F);
82. Delay_us(10);
83. i2c_lcd_command(0x01);
84. Delay_ms(10);
85. i2c_lcd_command(0x06);
86. Delay_us(10);
87. }
88. 
    
89. void main(){
90. unsigned int adc_rd;
91. char text[16];
92. long tlong;
93. float voltage;
94. ADPCFG = 0xFFFF; // Configure AN pins as digital
95. I2C1_Init(10000); // initialize I2C communication
96. Delay_ms(10);
97. i2c_lcd_init();
98. Delay_ms(10);
99. i2c_lcd_text("dsPIC30F2010 I2C");
100. i2c_lcd_line_2();
101. i2c_lcd_text("ADC PCF8574T LCD");
102. i2c_lcd_cursor_off();
103. Delay_ms(10000);
104. i2c_lcd_clear();
105. while(1){
106. adc_rd = ADC1_read(4); // get ADC value from 2nd channel
107. voltage = 5.0*adc_rd/1023;
108. i2c_lcd_line_1();
109. sprintf(text,"AN4 ADC: %4d 10", adc_rd);
110. i2c_lcd_text(text);
111. i2c_lcd_line_2();
112. sprintf(text,"Voltage: %.2f V", voltage);
113. i2c_lcd_text(text);
114. Delay_ms(500);
115. }
116. }

 

Using program C sprintf function is very easy to convert any data type into an array of ASCII characters. But it requires a lot of memory space. For limited ROM and RAM space, we can process the text, character, integer and floating point numbers one-by-one before sending it to UART or LCD stream. This post shows a simple number to ASCII character converting.

Archive: 

ADC Read Voltage 0.00 V

ADC Read Voltage 2.74 V

ADC Read Voltage 5.00 V

 See this short video on Youtube: