PIC Microcontrollers – Programming in C

What are microcontrollers, anyway? Electronics built in one single chip capable of controlling a small submarine, a crane or an elevator… It’s up to you to decide what you want them to do and dump a program containing appropriate instructions into the chip.

Author: Milan Verle

You can read the book online (or print it for that matter) at http://www.mikroe.com/en/books/pic-books/mikroc/ .

You can also order there the printed version of the book accompanied by a CD. Should you find the book useful you might want to consider buying it in order to support them.

If you want to see the source code (I’m not particulary proud of it )  drop a comment and I’ll send it to you.

If the bitmap is smaller than 128×64 it will be left as is, if not it will be resized proportionally to 128×64.

You can set the name you want your variable to have and you can also set if you want the picture inverted or not. Depending on your lcd colors you might want to invert the result.

You can download the converter here: glcd_convert.

The project is based on the source found here:

http://en.radzio.dxp.pl/ks0108/

The source is made pretty universal, still it took some work and modifications to have it working in mikroC. The archive is a ready working project for mikroC.

I tested and developed it on the EasyPIC5 development board with a PIC16F887 microcontroller. You have to have the board  configured for the touchscreen panel and GLCD display – i suppose you know how to do that, if not you should consult the EasyPIC5 manual.

The project has everything you need:

• a small demo program that uses text and bitmaps so you can see how the touchscreen, graphics, images and text work
• a font file
• a file to host your bitmap data
• graphic functions
• ks0108 functions
• microcontroller dependent functions.

Download everything HERE.

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bit oldstate;              // Old state flag
 
void main() {
  ANSEL  = 0;              // Configure AN pins as digital
  CMCON  = 7;              // Turn off the comparators
  TRISIO = 0;              // configure pins of GPIO as output
  TRISIO3_bit = 1;
  GPIO = 0xFF;
  do {
    if (Button(&GPIO, 3, 1, 1)) {  // Detect logical one
      oldstate = 1;                // Update flag
    }
    if (oldstate && Button(&GPIO, 3, 1, 0)) {
      // Detect one-to-zero transition
      GPIO = ~GPIO;               // Invert GPIO
      oldstate = 0;               // Update flag
    }                     // beginning of a repeat loop
  }  while(1);           // endless loop
}

Copy and paste the code above in MikroC PRO. You can use the free version as the PIC12F675 only has 1K flash memory. This small example changes the state of the LEDs on every press on the GPIO3 button (RA3 on the EasyPIC5). Don’t forget to set MCLR and oscillator as internal – so you get three extra pins! GPIO3 is input only so we will use it for a button. Should you want to test this on a breadboard or something similar this should be the schematic:

Check at the bottom for the latest updates.

Linux internet radio inside a vintage Blaupunkt radio case

When I first had the ideea I noticed an old ~ ’50s Blaupunkt Radio my father had in his basement. I investigated if the radio was worth restoring but the inside was rusted, the capacitors were long gone and most of the tubes were missing. It was more a case of rebuilding rather than restoring. I checked around the internet and saw that many models like this one existed, so it was not rare. And so, the radio was gutted and the insides went away. I cleaned and repaired the case as best as I could.

The first ideea was to have a big harddrive inside, an amp and external speakers hooked to it. It worked like this for a while until the motherboard I used fried and so did the amp. The project was eventualy put aside.

Anyways recently, I aquired an old Pentium III Compaq. By the case I could swear it was a small motherboard. It was NOT, and also the custom compaq psu had very short wires, but I managed to fit it inside. Since I have a media center pc hooked to the tv and the surround with all the music on it I decided to change the original ideea and make it what it originally was: a radio.

So, I gutted an old set of very good sounding Altec Lansing computer speakers and installed the small amp and speakers inside. I also mounted the motherboard and psu inside. One small fan on a side does the job of cooling everything down. I use one of the buttons on the front for the amp and another one for the computer.

I gave up the harddrive from the original design for a compact flash <-> ide adapter and the system now boots from a 4 Gb compact flash card. I think I could have squeezed everything on a smaller card but I decided to do all the compiling in place and since cards are cheap I went for a big one. The adapter has space for a second card and, if I want I can fit a second, bigger card, to hold some music.

I have a usb numpad for control and the usb lcd display featured some time ago on this site for display.

Software:

• mpd for playback
• mpc for mpd control
• Lcdproc and lcd-stuff for usb lcd display
• esekeyd for numpad control
• a bunch of bash scripts to glue everything in place

I hit a few problems:

• Event Music Player Client daemon does not work, at least with my keypad. So I had to use an external daemon – esekeyd with mpc to control mpd.
• lcd-stuff does not display the Name tag (that would be the radio station name, just the artist and track name. Fortunately it has a configuration tag to use as a title for the screen – on every playlist change a bashscript modifies that configuration setting to reflect the radio station’s name and reloads lcd-stuff – it’s ugly but it works.
• I didn’t find a way to save .pls and .m3u files and have them recognized by the mpd database. So a script is called at boot time (and also can be started from one of the keys on the keypad) to generate a playlist of the radio stations. Control is easy after that, it’s a matter of play/stop, next / prev
• I wanted to have a way to shut down the system safely from the keypad. OTOH I didn’t want shutting down every time I hit the wrong key. But esekeyd doesn’t support combinations. So I had * create a file, / create a second one but only if the first file (created by *) existed and on backspace press verify if the two files exist and if yes poweroff.

I’ll post soon more photos, the insides and the configuration files and bash scripts used.

2011 Update

It never functioned reliably and so I decided on rebuilding it once more

• The Compaq Deskpro EN was reassembled and donated to charity.
• I bought the cheapest intel motherboard with an atom processor.
• With the motherboard I also bought a small, slim PSU which happened to have the loudest annoying fan I ever heard. Fortunately the motherboard and disk use small amounts of power so no heat is produced. I hooked the fan to 5v and now it’s quiet.
• I got a good deal on a pair of Microlab powered speakers (were the last in stock, open box) so I hooked those up to the radio. It’s still possible to use the insternal speakers but why would you want to
• Used a 500Gb sata disk that I also had around.
• Took the oportunity to update slackware, mpd and everything else to the latest versions.
• Took out the LCD until I can find time to build it in a nice case
• The usb numpad is still there but I’m having trouble finding a daemon that actually works between two reboots
• I use Client175 for web control and also Sonata on n800 and DroidMPD on my wife’s tablet to control it. Having 500Gb it’s got it’s music back (not only internet radio).
• Since playlist support seems to be better now I have each radio stored in a playlist that DroidMPD or Client175 can simply load.
• The best thing is that there are no custom hackish scripts left that could break all the time. It’s just stock mpd, playlists and the clients. Oh, I also have the command line clients installed for when I ssh into it using my n900.
• The only problematic thing left is the shitty usb wi-fi adapter I use (don’t know, might be the drivers) it’s slow and sometimes connection drops. I added ping -c1 GATEWAY_IP in cron every 2 minutes and this seems to help.

Somebody in the comments asked for the configurations and scripts  The original ones, from the compact flash should still be in backups somewhere but I don’t see how they could help, as they point to old or discontinued versions.  (lcd-stuff comes to mind). The configuration I use now is as stock as one can get with mpd. Let me know if you have questions about it and also please recommend me a daemon that can listen for keystrokes from the usb keypad and it’s stable.

Have fun.

I have a linux Jukebox !

Here’s a link to the datasheet.

Code is tested on the EasyPic5 board, but should work on other boards and / or compilers with minimal modifications. Anyways, if you were searching for an example written in C on how to read the ADC inside a pic microcontroler here it is:

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/*
 
  * Based on MikroElectronika ADC on LCD example
 
  * Uses self written ADC_Read function
 
*/
 
unsigned char ch;
unsigned int adc_rd;
char *text;
long tlong;
 
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;
 
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
 
unsigned adc_read2(char channel)
{
 
   switch (channel) {
    case 0: {
        ADCON0.CHS0 = 0;
        ADCON0.CHS1 = 0;
        ADCON0.CHS2 = 0;
        ADCON0.CHS3 = 0;
    }
    case 1: {
        ADCON0.CHS0 = 1;
        ADCON0.CHS1 = 0;
        ADCON0.CHS2 = 0;
        ADCON0.CHS3 = 0;
    }
    case 2: {
        ADCON0.CHS0 = 0;
        ADCON0.CHS1 = 1;
        ADCON0.CHS2 = 0;
        ADCON0.CHS3 = 0;
    }
    case 3: {
        ADCON0.CHS0 = 1;
        ADCON0.CHS1 = 1;
        ADCON0.CHS2 = 0;
        ADCON0.CHS3 = 0;
    }
    case 4: {
        ADCON0.CHS0 = 0;
        ADCON0.CHS1 = 0;
        ADCON0.CHS2 = 1;
        ADCON0.CHS3 = 0;
    }
 
 
   }
 
 
 
   ADCON0.GO_DONE = 1; // start conversion
   while (ADCON0.GO_DONE); // wait for conversion
   return (ADRESH << 8) + ADRESL; // return value
}
 
 
void main() {
  INTCON = 0;       // disable all interrupts
  ANSEL  = 0x04;    // Configure AN2 pin as analog input
  TRISA  = 0x04;
  ANSELH = 0;       // Configure other AN pins as digital I/O
 
  ADCON1.VCFG0 = 0; // set internal
  ADCON1.VCFG1 = 0;
  ADCON0.ADCS0 = 1; // use Vdd as reference
  ADCON0.ADCS1 = 0; // use Vcc as reference
  ADCON1.ADFM = 1;  // result is right Justified
  ADCON0.ADON = 1;  // enable A/D converter
 
 
 
  Lcd_Init();
  LCD_Cmd(_LCD_CURSOR_OFF);     // send command to LCD (cursor off)
  LCD_Cmd(_LCD_CLEAR);                      // send command  to LCD (clear LCD)
 
  text = "mikroElektronika";    // assign text to string
  LCD_Out(1,1,text);            // print string a on LCD, 1st row, 1st column
  text = "LCD example";         // assign text to string
  LCD_Out(2,1,text);            // print string a on LCD, 2nd row, 1st column
 
  ADCON1     = 0x82;            // configure VDD as Vref, and analog channels
  TRISA      = 0xFF;            // designate PORTA as input
  Delay_ms(2000);
  text  = "voltage:";           // assign text to string
  while (1) {
    // let's use our open source function
    adc_rd  = ADC_read2(2);     // get ADC value from 2nd channel
    LCD_Out(2,1,text);          // print string a on LCD, 2nd row, 1st column
 
    tlong = (long)adc_rd * 5000;   // covert adc reading to milivolts
    tlong = tlong / 1023;          // 0..1023 -> 0-5000mV
 
    ch     = tlong / 1000;        // extract volts digit
    LCD_Chr(2,9,48+ch);           // write ASCII digit at 2nd row, 9th column
    LCD_Chr_CP('.');
 
    ch    = (tlong / 100) % 10;   // extract 0.1 volts digit
    LCD_Chr_CP(48+ch);            // write ASCII digit at cursor point
 
    ch    = (tlong / 10) % 10;   // extract 0.01 volts digit
    LCD_Chr_CP(48+ch);           // write ASCII digit at cursor point
 
    ch    = tlong % 10;       // extract 0.001 volts digit
    LCD_Chr_CP(48+ch);        // write ASCII digit at cursor point
    LCD_Chr_CP('V');
 
    Delay_ms(1);
  }
}

Please note that I only checked for the first 4 channels in the adc_read2 function. It’s easy to check for the other ADC channels using this table:

So, this would be free lunch for your brain. Even if you don’t use or plan to use Mikroelektronika products you might want to know that they have a free book about PIC microcontrolers on their website: here.

It’s not tied up to any of their development systems but it does focus on the PIC16F887, and even if the English used is not the best possible it still gets the job done.

It’s a good read, especially for beginners. It has clear color diagrams, examples, schematics and much more. It’s been really helpful for me.

Again, if you missed the link you can read the full book for free here.

Temperature line graph showing on the GLCD mounted on the EasyPic 5 development board

I am using a PIC16F887 mounted on the board. You might need to adjust the code if you use a different microcontroler / development board. Also I have the DS1820 mounted in it’s place with the jumper conecting it to RE2.

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// Conexiuni GLCD
 
char GLCD_DataPort at PORTD;
 
sbit GLCD_CS1 at RB0_bit;
sbit GLCD_CS2 at RB1_bit;
sbit GLCD_RS  at RB2_bit;
sbit GLCD_RW  at RB3_bit;
sbit GLCD_EN  at RB4_bit;
sbit GLCD_RST at RB5_bit;
 
sbit GLCD_CS1_Direction at TRISB0_bit;
sbit GLCD_CS2_Direction at TRISB1_bit;
sbit GLCD_RS_Direction  at TRISB2_bit;
sbit GLCD_RW_Direction  at TRISB3_bit;
sbit GLCD_EN_Direction  at TRISB4_bit;
sbit GLCD_RST_Direction at TRISB5_bit;
 
//  Seteaza TEMP_RESOLUTION la rez. coresp. senzorului DS18x20:
//  18S20: 9  (default; poate fi 9,10,11 sau 12)
//  18B20: 12
 
const unsigned short TEMP_RESOLUTION = 9;
 
char *text = "000.0000";
unsigned temp;
char posx; // pozitia liniei de temperatura
 
void SetTempTextGfx(unsigned int temp2write) {
  const unsigned short RES_SHIFT = TEMP_RESOLUTION - 8;
  char negative,temp_whole;
  unsigned int temp_fraction;
 
  negative = 0;
  // verificam daca temperatura este negativa
  if (temp2write & 0x8000) {
     text[0] = '-';
     temp2write = ~temp2write + 1;
     negative = 1;
     }
  // extrage temp_whole
  temp_whole = temp2write >> RES_SHIFT ;
  // la capatul ecranului se reia de la inceput
  if (posx == 128) {
   Glcd_box(4,0,128,41,0);
   Glcd_box(4,43,128,64,0);
   posx = 4;
  }
  // stergem liniile vechi
  Glcd_V_line(0,41,posx,0);
  Glcd_V_line(43,64,posx,0);
 
  // desenam linia noua
  if (negative == 0)
     Glcd_V_line(41-temp_whole,41,posx,1);
  else
     Glcd_V_line(43,43+temp_whole,posx,1);
  posx=posx+2;
  // converteste temp_whole in text
  if (temp_whole/100)
     text[0] = temp_whole/100  + 48;
  else
     text[0] = '0';
 
  text[1] = (temp_whole/10)%10 + 48;             // Extrage cifra zecilor
  text[2] =  temp_whole%10     + 48;             // Extrage cifra unitatilor
 
  // extrage temp_fraction si o converteste la unsigned int
  temp_fraction  = temp2write << (4-RES_SHIFT);
  temp_fraction &= 0x000F;
  temp_fraction *= 625;
 
  // converteste temp_fraction in caractere
  text[4] =  temp_fraction/1000    + 48;         // Extrage cifra miilor
  text[5] = (temp_fraction/100)%10 + 48;         // Extrage cifra sutelor
  text[6] = (temp_fraction/10)%10  + 48;         // Extrage cifrazecilor
  text[7] =  temp_fraction%10      + 48;         // Extrage cifra unitatilor
 
}
 
void main() {
  short i;
 
  ANSEL  = 0;           // Configureaza pinii AN ca I/O digitali
  ANSELH = 0;
  C1ON_bit = 0;         // Dez. comp.
  C2ON_bit = 0;
 
  Glcd_Init();          // Initializeaza GLCD
  Glcd_Fill(0x00);      // Sterge GLCD
 
  posx = 4;
 
    Glcd_V_Line(0,64,3,1);
    Glcd_H_Line(0,128,42,1);
    for (i=0;i<64;i=i+2) Glcd_H_Line(0,3,i,1);
 
  do {
    // citirea temperaturii
    Ow_Reset(&PORTE, 2);                         // Semnal reset Onewire
    Ow_Write(&PORTE, 2, 0xCC);                   // Comanda SKIP_ROM
    Ow_Write(&PORTE, 2, 0x44);                   // Comanda CONVERT_T
    Delay_us(120);
 
    Ow_Reset(&PORTE, 2);
    Ow_Write(&PORTE, 2, 0xCC);                   // Comanda SKIP_ROM
    Ow_Write(&PORTE, 2, 0xBE);                   // Comanda READ_SCRATCHPAD
 
    temp =  Ow_Read(&PORTE, 2);
    temp = (Ow_Read(&PORTE, 2) << 8) + temp;
 
    // Formateaza si afiseaza pe ecran
 
    SetTempTextGfx(temp);
    Glcd_Write_Text(text,80,7,1);
    Delay_ms(1000);
  } while (1);
}

The project

The design is based around a PIC18F2550 from Microchip. You will also need an LCD screen, one that is up to 20×4 and HD44780 or KS0066U compliant. The design can also accommodate some GPOs, a rotary encoder and a buzzer. I plan to add the rotary encoder soon.

Just the screen

The screen all up and running.

Soldering the connector for the LCD screen

I soldered a female connector to the LCD board so I can connect the screen both to my Easy Pic 5 development board and the USB backpack.

All done and working

All done and working

For now I tested the screen with Lcdsmartie but later on I plan to use it with lcdproc on linux.

The custom made board

The board, closer

Should the thread or the board disappear just drop a comment and I can mirror the .hex file, the schematic and the pcb layout.