The communication cable to the PC is made as specified in the PicBasic Compiler Manual.

	1.0K		DB9
pin	--/\/\/\----	RS-232 RX	Pin 2
GND	------------	RS-232 GND	Pin 5

This Project saves Data to an external EEPROM. First, if the C3 switch is open, the system gathers data in through the A to D on RA0. If the pin is high (jumpered with a resistor to supply) the chip sends the data out to the PC.
See "PicDisplay" for more details.

I2C protocols allow for easy transfer of information to an external device. the syntax in as follows
I2COUT Control, Address, ( Value{,Value})

I2COUT being the command
Control being the chip setup info.
1xxxxxxx, 16bit chip - 0xxxxxxxx, 8bit chip.
x1010xxx, chip specific. Look it up, the 24LC256 was 1010.
xxxxxXXX, device select bits.

Address being the memory location.

Values being the variable your playing with.

I2CIN is pretty much the same but reversed in function.
I2CIN Control, Address, Var{,Var}
One important consideration, it takes about 10ms for it to occur. Thus the pause after.

This project Requires the modification of the include file "PBL.INC". It should be located in your compilers directory. Since I wanted to do both analog and digital signals on PortA, I decided it would be best to relocate the I2C protocols from the standard pins 0 and 1 to pins 4 and 5. This way I could use pin 0 as an analog input.

Doing this is really quite easy. Simply open up pbl.inc with any text editor. Scroll down to the I2C stuff (as shown)

Then change the port pins to whatever you want. In this case 4 and 5.

'******** Writing to External EEPROM with a PIC ***************
'****************************************************** 
'@ Platform: PicBasic 
'@ Version: 1.0
'@ Author: Brian Patton (brianp@robodyssey.com)
' 		  Robodyssey Systems, LLC. - www.robodyssey.com
'@ Last Updated: Feb, 20, 2004
'******************************************************
' This Program uses the 16F876 
'*********Materials**************************************
' 1 Robodyssey PicPac MotherBoard
' 1 Pic16F876 or similar
' 1 Voltage Divider board
' 1 Variable Resistor (pot)or photoresistor
' 1 10k resistor to act as switch on C3
' 1 I2C EEPROM (I used the 24LC256)
' PicBasic Compiler and a programmer
'******************************************************
' Register Locations
Symbol  TRISA  = $85	' Register Location of TRISA
Symbol  ADCON0 = $1F	' Register location of ADCON0
Symbol  ADCON1 = $9F	' Register Location of ADCON1
Symbol  ADRESH = $1E	' Register Location of ADRESH
Symbol  TRISC  = $87	' Register Location of TRISC
Symbol  PortC  = 7		' Register Location of PortC

'***** Variables *****************************************
Symbol addr = w0			' The bigger EEPROMs need 16 bit addresses
Symbol value = b2 			' Place for the data
Symbol cont = %11010000	' EEPROM control byte
Symbol ADcon = b3		' storag spot for A to D functions
Symbol Cstatus = b4 		' Check state of Port C variable
'***** Initiation *****************************************
Init:
	Dirs = %11111111			' Set all Port B to output
	Poke ADCON1,%00000100 	'  Pins 0,1 and 3 analog input. Pins 2,4 and 5 digital.
			' 0xxxxxxx Sets result to Left justified
			' 1xxxxxxx Sets result to Right justified		
	Poke TRISC, %11111111	' Set all PortC Input

'**********Main Code Block Area***************************
Peek PortC,Cstatus		'Get the status of Port C
Cstatus = Cstatus & %00001000	'Set to 0 all but C3
If Cstatus = 0 Then gather	'If open then Gather Data
						'If closed then Recall Data
'*********** Get Data Back Out ****************************
recall:
For addr=1 to 1000
	I2Cin cont,addr,value	'See explanation above this code
	Serout 0,N2400,("Recalling Data ",#value,10,13)	'display value
	Pause 20
Next
	End

'********** Sample and store Data **************************
gather:
	Serout 0,N2400,("Gathering Data",10,13)	'Display "Gathering Data" on the PC screen
	Pause 3000
Start:
	Poke TRISA, %00000001		'Set pin0, PortA Input
'******** A to D Operation ********************************
AD0chk:
For addr = 1 to 1000		'addr is a 16 bit variable

    	Poke ADCON0, %11000001  'Set A/D to RC Osc, Channel 0, A/D converter ready
		'xx000xxx-Chan 0(RA0), xx001xxx-Chan 1(RA1),
		'xx010xxx-Chan 2(RA2), xx011xxx-Chan 3(RA3),
		'xx100xxx-Chan 4(RA4), xx101xxx-Chan 5(RA5),
		'xx110xxx-Chan 6(RA6), xx111xxx-Chan 7(RA7),

    	ADcon = %11000101			'xxxxx1xx - on, xxxxx0xx - off
        Poke ADCON0,ADcon			' Turn on the conversion at Bit 2

AD0fin: 
        Peek ADCON0,ADcon
 		If ADcon = %11000101 Then AD0fin   
			 ' Wait for low on bit-2 of ADCON0, conversion finished
    	Peek ADRESH,value
		Serout 0,N2400,(#addr," = ",#value,10,13)	'display value
		I2Cout cont,addr,(value)
		Pause 10				 'Need time to write
Next
	End