i2c PBP questions

[mister_e]

This device support high speed I2C clock... no need too add I2C_SLOW define.

Double check that you didn't revert SDA & SCL and that you have place 1 pull-up (4.7k or lower) on SDA and SCL lines.

Forget the ICD stuff and try this one

        '
        '       Device configuration fuses
        '       ==========================
        '       4MHz Clock     ---------> XT
        '       WatchDog Timer ---------> ON
        '       PowerUp Timer  ---------> ON
        '       BrowOut Detect ---------> ON      
        '       LowVoltage programming -> OFF
        '
        @   __CONFIG _XT_OSC & _WDT_ON & _PWRTE_ON & _BODEN_ON & _LVP_OFF 
        '
        '       ---------------------------------------------------------------
        '       If you're using PM assembler, you must change the above line 
        '       for the following
        '
        '       @   DEVICE PIC16F877A, XT_OSC, WDT_ON, PWRT_ON, BOD_ON, LVP_OFF
        '       ---------------------------------------------------------------        

        '       
        '       Hardware configuration
        '       ======================
                '
                '   I/O PORT
                '   --------
        TRISC = %10000000
        TRISD = 0
        TRISE = 0
                '
                '   USART
                '   ----- 
                '   Baudrate = 19200                  
                '
        DEFINE HSER_RCSTA 90h               ' Enable serial port & continuous receive
        DEFINE HSER_TXSTA 24h               ' Enable transmit, BRGH = 1
        DEFINE HSER_SPBRG 12                ' 19200 Baud @ 4MHz, 0.16%
                '
                '   ADC
                '   ---
        ADCON1 = 7                          ' set all related i/o to digital
        
        '
        '       Hardware assignments
        '       ====================
                '
                '   I2C BUS
                '   -------
                '   4.7K (or less) pull-up resistor on SDA & SCL line
                '   
                '   24LC512 
                '   -------
                '   A0 - A2 pin -> GND 
                '   WP pin ------> GND  
                '
        SDA var PORTC.4                     ' I2C bus SDA line 
        SCL var PORTC.3                     ' I2C bus SCL line
                '   
                '   LCD
                '   ---
                '   4 bits mode
                '   Data DB<7:4> -> PORTD<7:4>
                '   RS -----------> PORTE.0
                '   E ------------> PORTE.1
                '   R/W ----------> GND
                '   Vo -----------> 10-20K Trim pot wiper
                '
        DEFINE LCD_DREG PORTD               ' LCD data port
        DEFINE LCD_DBIT 4                   ' LCD data starting bit
        DEFINE LCD_RSREG PORTE              ' LCD register select port
        DEFINE LCD_RSBIT 0                  ' LCD register select bit
        DEFINE LCD_EREG PORTE               ' LCD enable port
        DEFINE LCD_EBIT 1                   ' LCD enable bit
        DEFINE LCD_BITS 4                   ' LCD data bus size
        DEFINE LCD_LINES 2                  ' Number lines on LCD
        DEFINE LCD_COMMANDUS 2000           ' Command delay time in us
        DEFINE LCD_DATAUS 50                ' Data delay time in us

        '
        '       Internal EEPROM assignement
        '       ===========================
        data @0, "Good",13,10
        data     "Bad ",13,10   
            
        '
        '       Variable definition
        '       ===================
        ADDR            var word               
        Data_READ       var byte               
        Data_Write      var byte               
        IsBad           var bit
        TotalBad        var word
        PicEepromAddr   var byte
        Char            var byte
                    
        '
        '       Software constants
        '       ==================                
        Control         con $A0             ' 24LC512 control byte 
                    
        '
        '       Program start
        '       =============
                '
                '   Hardware and software initialisation
                '   ------------------------------------
        PORTC = 0 
        PORTD = 0
        PORTE = 0 
        clear                               ' clear all variable
        pause 500                           ' LCD start-up delay
        lcdout $FE,1                        ' clear LCD
                    '       
                    '       Send repport header via serial communication
                    '       --------------------------------------------
        hserout ["    ADDR    Data_Write    Data_READ    Good/Bad",13,10,_
                 "    ----    ----------    ---------    --------",13,10]    

                '
                '       EEPROM write, read & test loop           
                '       ------------------------------
                '       1) write to EEPROM the LowByte value of current
                '          address (ADDR) value.
                '
                '       2) read it back and compare results
                '               case it's different: 
                '                   set 'IsBad' flag bit
                '                   increment 'TotalBad' variable value
                '
                '       3) Show results on LCD
                '
                '       4) Send results via serial communication @ 19200 bauds 
                '   
        For addr=0 to $FFFF
            IsBad=0                         ' set as good results
                                            
            data_write=addr.lowbyte         ' get the LowByte of current EEPROM
                                            ' address
                                            
            I2CWRITE sda,scl,control,ADDR,[data_write] : PAUSE 5 
                                            ' send it to the EEPROM and
                                            ' wait max Twc delay
                                            
            I2CREAD  sda,scl,control,ADDR,[Data_read]
                                            ' read the current data 
                                            ' at the current address
                                            
            if data_read != data_write then ' data stored is different?
                                            '    YES!
                IsBad  = 1                  '    set bad result flag
                totalbad = totalbad + 1     '    increment total of bad result
                endif                       
                    '
                    '       Show data on LCD
                    '       ----------------
            lcdout $FE,2,"W:",hex4 data_write,"   R:",hex4 data_read,_    
                   $FE,$C0,"TotalBad=", dec totalbad                        
                    '
                    '       Send data via serial communication
                    '       ----------------------------------
                            '
                            '   Show : Current address
                            '          Data_Write 
                            '          Data_read
                            '
            hserout [rep " "\4,hex4 addr, rep " "\7, hex4 data_write ,_
                     rep " "\10,hex4 Data_read,rep " "\8]
                            '
                            '   Show if the actual reading is "Good"
                            '   or "Bad"
                            '
            for piceepromaddr=(IsBad*6) to ((IsBad*6)+5)
                read piceepromaddr, char    ' read character from PIC EEPROM
                hserout [char]              ' send it
                next
                                              
            next        
                '
                '       *******************************
                '       *    the whole job is done    *
                '       *******************************
                '
                '       Show the amount of bad results
                '       ------------------------------
        hserout [rep " "\4,rep "="\43,13,10,_
                 rep " "\4,"TotalBad = ",dec totalbad,13,10]
                 
        lcdout $FE,1,"TotalBad=",dec totalbad

SpinHere:
        goto spinhere                       ' spin in round forever

[TimV]

Hi Steve:

Thanks for the suggestions and the code. I am just building my proto type board, and so far, I have the LCD working and 2 dual segment 7 segment displays running off a MAX7219. That is all that is working at this time. I am trying to get the i2c working next.

I do not have the rs232 link working yet, so I can't implement your suggestion below.

I have confirmed the SDA and SCL connections at the IC with a meter on the pin while single stepping the code. I am getting 2.03 volts at both SDA and SCL and I do have a 4k7 resistor on each line.

The ICD 2 is both my debugger and my programmer and it is my only interface to the 16F877a at the moment.

I will check all the wiring as I have prewired the DS1307 and DS1631 sockets. They checked out with a meter when I tested SDA and SCL, but I will have a close look again.

thanks

tim

[TimV]

Hi:

I did some rewiring as I have found in the past that a particular type of 8 pin socket that seems to be the only kind I can get has caused me problems. I wired an 18Pin socket of the type I like for the 24AA512 and the DS1307.

As embarrassing as it is, since this is a forum and a post that someone else might read and benefit from, here is some information that should be checked. (And more than once it seems)

Pin 7 on the EEPROM is WP (Write Protect). If it is high, you cannot write to the EEPROM. I had missed the mark by one tiny little hole on my proto board and wired WP high.

I discovered this after rewiring to the new socket and having the same problem writing to the EEPROM. This time, I had forgotten to add the wire for WP at all. I measured with the meter and found that if left floating, WP will be high.

I destroyed the EEPROM by accidently by taking too long to clear a solder bridge with the iron when trying to wire WP low.

So, I have moved on the the DS1307 RTC. I have yet to read back the config properly (I get "16") when I send the value LCDOUT, $FE, $80, #CONFIG where "CONFIG" is the value sent after Year to address $07. I think that is telling me that I am reading "FF" from the config register which I know from previous experience is telling me that I am not talking to the DS1307.

It was getting late, and I packed it in. I will have another look at it tonight.

Sorry to have missed the WP on the EEPROM. Too bad I burned it out. I was hoping for the best.

If I can't get the DS1307 to run properly, I will move on to the One-Wire phase of bringing the board on line. Hopefully that will not be a difficult as the i2c has been

thanks for the help

Tim