Digital Intercom

History

This project was inspired by my girlfriend, who asked me to build an intercom for our house. There are many ways to build an intercom; an example is batteries in series with 2 telephones, a key switch and an amplifier. I felt this was far too simple. I decided to build an intercom with an MCU which digitalizes a voice and then sends it serially and then regenerates the analog signal. I equipped the microphone with an ACG to ensure that anyone in between 1 inch and 10 feet from the microphone will sound good. After that I send the analog signal to the A/D of my MCU which digitalizes the voice and sends it serially to the other intercom that you have previously set the "address" for. The digital signal is sent to an RS422 interface, which sends it to a RS422 hub, which then broadcasts the data to the other intercoms. The addressed intercom takes the data and regenerates the analog signal via a PWM and a simple analog filter. I found a really cool 3 Watt Amplifier which works at 12 volts with a pin to control the output volume.

Features

	LCD
	AGC
	Simple power amplifier with volume control
	PWM generated D/A
	Sine wave generator for key sound and pre-tone

Pictures

Click to enlarge

PCB

PCB Mount

Front

Finish

Sources codes & Schematics

-Schematic of the intercomm in PDF format

-Schematic of the hub in PDF format

//***************************************************************************** // InterCom // Version 1.0 Sep 2005 // // 1.0 -> -Everything is new // // Sylvain Bissonnette //***************************************************************************** // Editor : UltraEdit32 //***************************************************************************** // // R E T U R N S T A C K 3 2 // X T A L 16 MHZ // BootLoader of 1024 word // //***************************************************************************** // // F U S E B I T // //( )7 ( )6 ( )BL12 ( )BL11 ( )BL02 ( )BL01 ( )Lock2 ( )Lock1 //( )7 ( )6 ( ) ( ) ( ) ( )M103C ( )WDTON ( ) //( )OCDEN ( )JTAGE (X)SPIEN(X)CKOPT (X)EESAVE ( )BOOTSZ1 (X)BOOTSZ0 (X)BOOTRST //(X)BODLEV (X)BODEN ( )SUT1 (X)SUT0 ( )CKSEL3 (X)CKSEL2 ( )CKSEL1 ( )CKSEL0 // //***************************************************************************** // P I N U S A G E // // PA0 -> GND // PA1 -> A/D input from Microphone // PA2 -> GND // PA3 -> GND // PA4 -> GND // PA5 -> GND // PA6 -> GND // PA7 -> GND // // PB0 -> Keypad ROW1 // PB1 -> Keypad ROW2 // PB2 -> Keypad ROW3 // PB3 -> Keypad ROW3 // PB4 -> Keypad COL1 // PB5 -> Keypad COL2 // PB6 -> Keypad COL3 // PB7 -> Keypad COL4 // // PC0 -> LCD DB7 // PC1 -> LCD DB6 // PC2 -> LCD DB5 // PC3 -> LCD DB4 // PC4 -> LCD E // PC5 -> LCD R/W // PC6 -> LCD RS // PC7 -> LCD BackLight // // PD0 -> Net_RX // PD1 -> Net_TX // PD2 -> +5 // PD3 -> LED // PD4 -> PWM Volume // PD5 -> PWM Voice // PD6 -> Ampli Standby // PD7 -> LCD Contrast // //***************************************************************************** // T I M E R U S A G E // // Timer 0 is use for 20khz sampling & reproducing voice // Timer 1 is use for 62.5khz PWM voice reproducing and volume // Timer 2 is use for LCD Contrast // Timer 3 not use // //***************************************************************************** //***************************************************************************** // I N C L U D E //***************************************************************************** #include <iom32v.h> #include <shortnametype.h> #include <macros.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <eeprom.h> //***************************************************************************** // D E F I N E //***************************************************************************** #define VERSION 10 #define TRUE 1 #define FALSE 0 #define XTAL 16000000 #define VOICEBUFFER 64 #define OFF 0 #define TALK 1 #define LISTEN 2 #define TONE 3 #define BUSY 4 #define PWM_VOICE 0x20 #define PWM_VOLUME 0x10 #define AMPLI_STANDBY 0x40 #define EEPROM_VOLUME 1 #define EEPROM_ADDRESS 2 #define EEPROM_KEYSOUND 3 #define EEPROM_KEYSOUNDVOLUME 4 #define EEPROM_KEYSOUNDTONE 5 #define EEPROM_KEYSOUNDLEN 6 #define EEPROM_BROADCAST 7 #define LED 0x08 #define MAXITEM 20 // Network #define NET_DDR DDRD #define NET_PIN PIND #define NET_PORT PORTD #define NET_RX 0x01 #define NET_TX 0x02 #define NET_UBRRH UBRRH #define NET_UBRRL UBRRL #define NET_UCSRA UCSRA #define NET_UCSRB UCSRB #define NET_UCSRC UCSRC #define NET_UDR UDR #define NET_SPEED 500000 #define NET_GET_ADDRESS EEPROMread(EEPROM_ADDRESS); // LCD #define LCD_D7 0x01 #define LCD_D6 0x02 #define LCD_D5 0x04 #define LCD_D4 0x08 #define LCD_E 0x10 #define LCD_RW 0x20 #define LCD_RS 0x40 #define LCD_BACKLIGHT 0x80 #define LCD_PIN PINC #define LCD_DDR DDRC #define LCD_PORT PORTC #define LCD_DATA 0x01 #define LCD_CTRL 0x00 #define LCD_C_BLINK_ON 0x09 #define LCD_C_BLINK_OFF 0xfe #define LCD_C_ON 0x0a #define LCD_C_OFF 0xfd #define LCD_DISPLAY_ON 0x0c #define LCD_DISPLAY_OFF 0xfb #define LCD_BRIGHT_25 0x23 #define LCD_BRIGHT_50 0x22 #define LCD_BRIGHT_75 0x21 #define LCD_BRIGHT_100 0x20 #define LCD_BACKLIGHT_ON 0x24 #define LCD_BACKLIGHT_OFF 0x25 // Key #define KEY_PIN PINB #define KEY_DDR DDRB #define KEY_PORT PORTB // Keypad #define ROW1 0x02 #define ROW2 0x04 #define ROW3 0x08 #define ROW4 0x10 #define COL1 0x20 #define COL2 0x40 #define COL3 0x80 #define COL4 0x80 #define RESET 20 //***************************************************************************** // C O N S T A N T //***************************************************************************** // SineTable const ushort SineTable[256] = {133,136,139,142, 145,149,152,155, 158,161,164,167, 169,172,175,178, 181,184,186,189, 192,194,197,200, 202,205,207,209, 212,214,216,218, 220,222,224,226, 228,230,232,233, 235,237,238,240, 241,242,243,245, 246,247,248,248, 249,250,251,251, 252,252,252,253, 253,253,253,253, 253,253,252,252, 252,251,251,250, 249,248,248,247, 246,245,243,242, 241,240,238,237, 235,233,232,230, 228,226,224,222, 220,218,216,214, 212,209,207,205, 202,200,197,194, 192,189,186,184, 181,178,175,172, 169,167,164,161, 158,155,152,149, 145,142,139,136, 133,130,127,124, 121,118,115,112, 109,105,102,99, 96,93,90,87, 85,82,79,76, 73,70,68,65, 62,60,57,54, 52,49,47,45, 42,40,38,36, 34,32,30,28, 26,24,22,21, 19,17,16,14, 13,12,11,9, 8,7,6,6, 5,4,3,3, 2,2,2,1, 1,1,1,1, 1,1,2,2, 2,3,3,4, 5,6,6,7, 8,9,11,12, 13,14,16,17, 19,21,22,24, 26,28,30,32, 34,36,38,40, 42,45,47,49, 52,54,57,60, 62,65,68,70, 73,76,79,82, 85,87,90,93, 96,99,102,105, 109,112,115,118, 121,124,127,127}; //***************************************************************************** // P R O T O T Y P E //***************************************************************************** void main(void); void DoVolume(void); void DoKey(ushort ReGen); void SetKeySoundLen(void); void SetKeySoundTone(void); void SetKeySoundVolume(void); void SetKeySound(void); void SetBroadCastEnable(void); void SetStationAddress(void); void StationCall(ushort Station); void BroadCastCall(void); void _StackOverflowed(char c); void Led(void); void Info(void); void Delay(ushort Del); // A/D void ADInit(void); void ADStart(void); void ADDone(void); // Voice void VoiceEnginInit(void); void VoiceEngin(void); void VoiceVolume(ushort Vol); // Network void NetInit(void); void NetSendCommand(ushort To,ushort Command); void NetDirectWriteByte(ushort Byte); void NetWriteByte(ushort Byte); ushort NetReadByte(void); ushort NetGetInByteCount(void); void NetRxByte(void); void NetTxByte(void); void NetGetAddress(void); // LCD void LCDInit(ushort x,ushort y); void LCDOff(void); void LCDClrSCR(void); void LCDGotoXY(ushort,ushort); ushort LCDWhereX(void); ushort LCDWhereY(void); void LCDWriteString(char *); void LCDWriteConstString(const char *); void LCDWriteChar(char); void LCDWriteData(ushort,ushort); ushort LCDReadData(ushort rs); void LCDCreateCHR(ushort chnumber, char *ptr); void LCDWait(void); void LCDDelay50us(int Delay); void LCDTextAttr(ushort attribute); void LCDContrast(ushort Cont); // Key void KeyInit(void); ushort KeyLook(void); void KeyScan(void); //***************************************************************************** // G L O B A L V A R I A B L E //***************************************************************************** // LCD ushort MaxX, MaxY, LCDStat; char Text[20]; // Keypad ushort Key; ushort KeySound; ushort KeySoundVolume; ushort KeySoundTone; ushort KeySoundLen; // Network ushort NetAddress; ushort DataInBuffer[VOICEBUFFER]; ushort *DataInBufferWrite; ushort *DataInBufferRead; uint DataInBufferQte; ushort DataOutBuffer[VOICEBUFFER]; ushort *DataOutBufferWrite; ushort *DataOutBufferRead; uint DataOutBufferQte; ushort InterCommMode; ushort IncommingCall; ushort Volume = 0x80; ushort Tone = 8; // Display char DisplayName[MAXITEM][13]; char DisplayValue[MAXITEM][6]; int DisplayQTE; // Others ushort BroadCastEnable; //***************************************************************************** // M A I N //***************************************************************************** void main() { WDR(); WDTCR = 0x0f; // Watch Dog enable LCDInit(20,2); KeyInit(); NetInit(); ADInit(); VoiceEnginInit(); SEI(); //re-enable interrupts EEPROM_READ(EEPROM_VOLUME, Volume); EEPROM_READ(EEPROM_KEYSOUND, KeySound); EEPROM_READ(EEPROM_KEYSOUNDVOLUME, KeySoundVolume); EEPROM_READ(EEPROM_KEYSOUNDTONE, KeySoundTone); EEPROM_READ(EEPROM_KEYSOUNDLEN, KeySoundLen); EEPROM_READ(EEPROM_BROADCAST, BroadCastEnable); if (KeySoundTone > 59) KeySoundTone = 59; if (KeySoundLen > 10) KeySoundLen = 10; Info(); InterCommMode = TONE; VoiceVolume(0x40); Delay(50); LCDClrSCR(); VoiceVolume(0); InterCommMode = OFF; IncommingCall = FALSE; DoKey(TRUE); while(1) { WDR(); _StackCheck(); if (KeyLook() == RESET) while(TRUE); if ((!IncommingCall) && (InterCommMode != BUSY)) DoKey(FALSE); if (IncommingCall) DoVolume(); } } /****************************************************************************** Name: void DoKey(void) Description: Input: none Output: none Misc: ******************************************************************************/ void DoVolume(void) { static int Ticker,VolumeChange=FALSE; Ticker++; Key = KeyLook(); if ((Key == 11) && (Volume < 255)) Volume++; if ((Key == 10) &&(Volume > 1)) Volume--; if (Key != 0xff) { Ticker = 0; VoiceVolume(Volume); VolumeChange = TRUE; LCDGotoXY(1,2); LCDWriteConstString(" \0"); LCDGotoXY(1,2); csprintf(&Text[0]," Volume :%d \0",Volume); LCDWriteString(&Text[0]); Delay(1); Key = 0xff; } if ((VolumeChange == TRUE) && (Ticker > 1000)) { EEPROM_WRITE(EEPROM_VOLUME, Volume); VolumeChange = FALSE; } } /****************************************************************************** Name: void DoKey(void) Description: Input: none Output: none Misc: ******************************************************************************/ void DoKey(ushort ReGen) { static ushort KeyFirst,KeySecond,Value,Update; Update = FALSE; if (ReGen) { LCDClrSCR(); LCDGotoXY(1,1); LCDWriteConstString(" InterComm V:1.0\0"); LCDGotoXY(1,2); LCDWriteData(LCD_DATA,KeySecond+48); LCDWriteData(LCD_DATA,KeyFirst+48); Value = (KeySecond * 10) + KeyFirst; Update = TRUE; } else { KeyScan(); if ((Key != 0xff) && (Key != 10) && (Key != 11)) { KeySecond = KeyFirst; KeyFirst = Key; LCDGotoXY(1,2); LCDWriteData(LCD_DATA,KeySecond+48); LCDWriteData(LCD_DATA,KeyFirst+48); Value = (KeySecond * 10) + KeyFirst; Update = TRUE; Key = 0xff; } } //-------------------- if (Update == TRUE) { LCDGotoXY(3,2); if (Value == 0) LCDWriteConstString("->Broadcast Call #\0"); else if ((Value >= 1) && (Value < 40)) LCDWriteConstString("->Calling # \0"); else if (Value == 99) LCDWriteConstString("->Set Address # \0"); else if (Value == 98) LCDWriteConstString("->Set Key Sound # \0"); else if (Value == 97) LCDWriteConstString("->Set Key Tone # \0 "); else if (Value == 96) LCDWriteConstString("->Set Key Volume #\0"); else if (Value == 95) LCDWriteConstString("->Set Tone Len # \0"); else if (Value == 94) LCDWriteConstString("->Set BroadCast # \0"); else if ((Value >= 40) && (Value < 95)) LCDWriteConstString("-> \0"); } //-------------------- if (Key == 11) { Key = 0xff; if (Value == 0) BroadCastCall(); else if ((Value >= 0) && (Value < 40)) StationCall(Value); else if (Value == 99) SetStationAddress(); else if (Value == 98) SetKeySound(); else if (Value == 97) SetKeySoundTone(); else if (Value == 96) SetKeySoundVolume(); else if (Value == 95) SetKeySoundLen(); else if (Value == 94) SetBroadCastEnable(); } } /****************************************************************************** Name: SetKeySoundLen(void) Description: Input: none Output: none Misc: ******************************************************************************/ void SetKeySoundLen(void) { static ushort KeyFirst,KeySecond,Value; LCDClrSCR(); LCDGotoXY(1,1); csprintf(&Text[0],"Current Tone : %d\0",KeySoundLen); LCDWriteString(&Text[0]); LCDGotoXY(1,2); LCDWriteConstString("New Tone(00-10):00\0"); while(TRUE) { WDR(); KeyScan(); if ((Key != 0xff) && (Key != 10) && (Key != 11)) { KeySecond = KeyFirst; KeyFirst = Key; LCDGotoXY(17,2); LCDWriteData(LCD_DATA,KeySecond+48); LCDWriteData(LCD_DATA,KeyFirst+48); Value = (KeySecond * 10) + KeyFirst; if (Value < 11) KeySoundLen = Value; Key = 0xff; } if (Key == 11) { Key = 0xff; if ((Value >= 0) && (Value < 11)) { EEPROM_WRITE(EEPROM_KEYSOUNDLEN, Value); LCDGotoXY(1,1); LCDWriteConstString(" New Value Saved \0"); Delay(75); LCDGotoXY(1,1); LCDWriteConstString(" --------------- \0"); DoKey(TRUE); return; } else { LCDGotoXY(1,1); LCDWriteConstString(" Value Out Of Range \0"); Delay(75); LCDGotoXY(1,1); LCDWriteConstString(" ------------------ \0"); DoKey(TRUE); return; } } } } /****************************************************************************** Name: SetKeySoundTone(void) Description: Input: none Output: none Misc: ******************************************************************************/ void SetKeySoundTone(void) { static ushort KeyFirst,KeySecond,Value; LCDClrSCR(); LCDGotoXY(1,1); csprintf(&Text[0],"Current Tone : %d\0",KeySoundTone); LCDWriteString(&Text[0]); LCDGotoXY(1,2); LCDWriteConstString("New Tone(00-59):00\0"); while(TRUE) { WDR(); KeyScan(); if ((Key != 0xff) && (Key != 10) && (Key != 11)) { KeySecond = KeyFirst; KeyFirst = Key; LCDGotoXY(17,2); LCDWriteData(LCD_DATA,KeySecond+48); LCDWriteData(LCD_DATA,KeyFirst+48); Value = (KeySecond * 10) + KeyFirst; if (Value < 59) KeySoundTone = Value; Key = 0xff; } if (Key == 11) { Key = 0xff; if ((Value >= 0) && (Value <59)) { EEPROM_WRITE(EEPROM_KEYSOUNDTONE, Value); LCDGotoXY(1,1); LCDWriteConstString(" New Value Saved \0"); Delay(75); LCDGotoXY(1,1); LCDWriteConstString(" --------------- \0"); DoKey(TRUE); return; } else { LCDGotoXY(1,1); LCDWriteConstString(" Value Out Of Range \0"); Delay(75); LCDGotoXY(1,1); LCDWriteConstString(" ------------------ \0"); DoKey(TRUE); return; } } } } /****************************************************************************** Name: SetKeySoundVolume(void) Description: Input: none Output: none Misc: ******************************************************************************/ void SetKeySoundVolume(void) { static ushort KeyFirst,KeySecond,Value; LCDClrSCR(); LCDGotoXY(1,1); csprintf(&Text[0],"Current Key Vol:%d\0",KeySoundVolume); LCDWriteString(&Text[0]); LCDGotoXY(1,2); LCDWriteConstString("New Key Vol 00-99:00\0"); while(TRUE) { WDR(); KeyScan(); if ((Key != 0xff) && (Key != 10) && (Key != 11)) { KeySecond = KeyFirst; KeyFirst = Key; LCDGotoXY(19,2); LCDWriteData(LCD_DATA,KeySecond+48); LCDWriteData(LCD_DATA,KeyFirst+48); Value = (KeySecond * 10) + KeyFirst; KeySoundVolume = Value; Key = 0xff; } if (Key == 11) { Key = 0xff; EEPROM_WRITE(EEPROM_KEYSOUNDVOLUME, Value); LCDGotoXY(1,1); LCDWriteConstString(" New Value Saved \0"); Delay(75); LCDGotoXY(1,1); LCDWriteConstString(" --------------- \0"); DoKey(TRUE); return; } } } /****************************************************************************** Name: SetKeySound(void) Description: Input: none Output: none Misc: ******************************************************************************/ void SetKeySound(void) { LCDClrSCR(); LCDGotoXY(1,1); if (KeySound) LCDWriteConstString("Key Sound is ON \0"); else LCDWriteConstString("Key Sound is OFF \0"); LCDGotoXY(1,2); LCDWriteConstString("* To Toggle #->Save\0"); while(TRUE) { WDR(); KeyScan(); if ((Key != 0xff) && (Key == 10)) { if (KeySound) KeySound = 0; else KeySound = 1; Key = 0xff; LCDGotoXY(1,1); if (KeySound) LCDWriteConstString("Key Sound is ON \0"); else LCDWriteConstString("Key Sound is OFF \0"); } if (Key == 11) { Key = 0xff; EEPROM_WRITE(EEPROM_KEYSOUND, KeySound); LCDGotoXY(1,1); LCDWriteConstString(" New Value Saved \0"); Delay(75); LCDGotoXY(1,1); LCDWriteConstString(" --------------- \0"); DoKey(TRUE); return; } } } /****************************************************************************** Name: SetBroadCastEnable(void) Description: Input: none Output: none Misc: ******************************************************************************/ void SetBroadCastEnable(void) { LCDClrSCR(); LCDGotoXY(1,1); if (BroadCastEnable) LCDWriteConstString("BroadCast is ON \0"); else LCDWriteConstString("BroadCast is OFF \0"); LCDGotoXY(1,2); LCDWriteConstString("* To Toggle #->Save\0"); while(TRUE) { WDR(); KeyScan(); if ((Key != 0xff) && (Key == 10)) { if (BroadCastEnable) BroadCastEnable = 0; else BroadCastEnable = 1; Key = 0xff; LCDGotoXY(1,1); if (BroadCastEnable) LCDWriteConstString("BroadCast is ON \0"); else LCDWriteConstString("BroadCast is OFF \0"); } if (Key == 11) { Key = 0xff; EEPROM_WRITE(EEPROM_BROADCAST, BroadCastEnable); LCDGotoXY(1,1); LCDWriteConstString(" New Value Saved \0"); Delay(75); LCDGotoXY(1,1); LCDWriteConstString(" --------------- \0"); DoKey(TRUE); return; } } } /****************************************************************************** Name: &nb