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serialEEPROM
- 1. ;******************************************************************************; ;@Date 02/07/2009 ;@Version 1.1 ;@Author Pedro Pablo Plazas R. ;@@@ Communication between Serial EEPROM 24LC04B(Slave) and PIC16F84A(Master) ; using 2-wire serial interface bus, I2C. ;Bus timing Start/Stop and data for a frequency equal to 6Mhz ;***************************************************************************** ;**** Signals ***** SDA equ 2 ;Signal data SCL equ 3 ;Signal clock CONSTANT CODE_DEVICE_W = b'10100000' ;Control byte for writting operations. CONSTANT CODE_DEVICE_R = b'10100001' ;Control byte for reading operations. ;***************************************************************** ; ;****************************************************************** EEPROM_init macro call EEP_init endm ;***************************************************************************** ;Rutine to write operation. ;Following the Start condition from the master, the device code(4 bits), ;the block address(3bits) and the R/W(-), bit which is a logic low is placed ;onto the bus by the master transmitter. ;***************************************************************************** EEPROM_Write_Data macro word_Address, data_Write call BIT_START ;//--Start bit call SEND_CMD_Writting ;//--Command to write (10100000) EEPROM_ACK movlw word_Address ;//--Send Word Address call SEND_Data_Or_Addr EEPROM_ACK movf data_Write,W ;//--Send byte to write. call SEND_Data_Or_Addr EEPROM_ACK ;//--ACK call BIT_STOP ;//--Stop bit endm ;******************************************************************* ;Page write. The write control byte, word address and the first data ;byte are transmitted to the 24XX04 in the same way as in a byte ;write. But instead of generating a Stop condition the master transmit ;up to 16 data bytes to the 24XX04. ;******************************************************************* EEPROM_Page_Write_Data macro word_Address, data_Write1, data_Write2 call BIT_START ;//--Start bit call SEND_CMD_Writting ;//--Command to write (10100000) EEPROM_ACK
- 2. movlw word_Address ;//--Send Word Address call SEND_Data_Or_Addr EEPROM_ACK movf data_Write1,W ;//--Send byte1 to write. call SEND_Data_Or_Addr EEPROM_ACK ;//--ACK movf data_Write2,W ;//--Send byte2 to write. call SEND_Data_Or_Addr EEPROM_ACK ;//--ACK call BIT_STOP ;//--Stop bit endm EEPROM_Read_Data macro word_Address call BIT_START ;//--Start bit call SEND_CMD_Writting ;//--Command to write (10100000) EEPROM_ACK ;//--ACK movlw word_Address ;//--Send Word Address call SEND_Data_Or_Addr EEPROM_ACK call BIT_START ;//--Start bit call SEND_CMD_Reading ;//--Command to read (10100001) EEPROM_ACK ;//--ACK call READ_DATA ;//--READ DATA BYTE bcf EEPportB,SCL nop bsf EEPportB,SCL nop bcf EEPportB,SCL nop call BIT_STOP ;///Stop bit endm ;***************************************************************** ;Init ports MAster(PIC16F84) for communication with Slave(EEPROM) ;***************************************************************** EEP_init BANK1 clrf EEPtrisA clrf EEPtrisB bsf EEPtrisB,0 ;Input to push key. BANK0 clrf EEPportA clrf EEPportB bsf EEPportB,SDA bsf EEPportB,SCL RETURN ;***************************************************************** ;Generate Start o Stop bit ;***************************************************************** BIT_START bcf INTCON,GIE BANK1 bcf EEPtrisB,SDA BANK0 bsf INTCON,GIE call SCLK_BIT_START RETURN BIT_STOP
- 3. bcf INTCON,GIE BANK1 bcf EEPtrisB,SDA BANK0 bsf INTCON,GIE call SCLK_BIT_STOP RETURN ;****************************************************************** ;Generating acknowlegde signal ;****************************************************************** EEPROM_ACK macro local ReadAck, EndAck bcf INTCON,GIE BANK1 bsf EEPtrisB,SDA BANK0 bsf INTCON,GIE ReadAck btfsc EEPportB,SDA goto ReadAck bsf EEPportB,SCL nop nop bcf EEPportB,SCL endm ;**************************************************************************** ; Send one command or data(only to write) for writting or reading into EEPROM ;**************************************************************************** SEND_CMD_Writting movlw CODE_DEVICE_W ;Control byte to write goto SEND_Data_Or_Addr SEND_CMD_Reading movlw CODE_DEVICE_R ;Control byte to read SEND_Data_Or_Addr movwf BYTE_TX bcf INTCON,GIE BANK1 bcf EEPtrisB,SDA BANK0 bsf INTCON,GIE movlw 0x08 movwf COUNT_BITS SENDCtrl btfsc BYTE_TX,7 goto SEND_SB bcf EEPportB,SDA goto ROT_BITS SEND_SB bsf EEPportB,SDA ROT_BITS call SCLK_DATA rlf BYTE_TX,1 decfsz COUNT_BITS,F goto SENDCtrl RETURN ;************************************************************ ;Reading data from EEPROM ;************************************************************
- 4. READ_DATA bcf INTCON,GIE BANK1 bsf EEPtrisB,SDA BANK0 bsf INTCON,GIE movlw .8 movwf COUNT_BITS ROT_DATA_BITS rlf REG_DATA,F btfss EEPportB,SDA bcf REG_DATA,0 btfsc EEPportB,SDA bsf REG_DATA,0 call SCLK_DATA decfsz COUNT_BITS,F goto ROT_DATA_BITS movf REG_DATA,W RETURN ;******************************************************* ;Rutine to generate start condition setup time ;******************************************************* SCLK_BIT_START bcf EEPportB,SCL bsf EEPportB,SDA nop nop bsf EEPportB,SCL nop nop bcf EEPportB,SDA nop nop bcf EEPportB,SCL nop nop RETURN ;******************************************************* ;Rutine to generate start condition setup time ;******************************************************* SCLK_BIT_STOP bcf EEPportB,SDA nop nop bsf EEPportB,SCL nop nop bsf EEPportB,SDA nop nop bcf EEPportB,SCL nop nop RETURN ;************************************************************** ;Generating signal of clock for EEPROM(SCL), only one period ;************************************************************** SCLK_DATA nop
- 5. nop bsf EEPportB,SCL nop nop nop nop bcf EEPportB,SCL RETURN ;**************************************** ;Routine to wait 100ms, to push any key ;**************************************** KeyWait movlw 0x96;--64(100ms) movwf RS_TIMER1 ;Delay of 1ms T_Wait movlw 0xFA movwf RS_TIMER2 T_Wx nop nop nop nop nop decfsz RS_TIMER2 goto T_Wx decfsz RS_TIMER1 goto T_Wait RETURN