What is it?

It’s an Eeprom programmer controlled by Bascom Avr and is capable of programming in circuit Eeprom’s up to 512Kb. Standard Intel Hex8 file is required.

Extended Linear Address Records for Eeprom’s bigger then 16bits addresses is not (yet) supported, but easy to implant.

I wrote it primary for my other application note RC2 sound / voice playback.

Required tools

For the PC side there’s an upload program that sends the Intel Hex file to the AVR.

Program is written in VB6-Sp6, source code is also available.

Note from MCS

I liked the idea of Evert very much and extended his application with an ASM-BIN converter so you do not need Studio to convert the files.

Click here for download archive with source code and schematic

The code

Code is written and tested in Bascom 1.11.9.0.001 license.

'--------------------------------------------------------------------
' I2C Eeprom programmer
'Upload your Eeprom files through serial connection in the I2c Eeprom
' No extended address supported, so max 512K Eeprom
' By Evert Dekker 2008 i2cprogrammer@Evertdekker dotje com
' Created with Bascom-Avr: 1.11.9.0.100
'--------------------------------------------------------------------

$regfile = "m128def.DAT"
$crystal = 16000000
$baud = 19200
$hwstack = 70
$swstack = 70
$framesize = 60

$lib "I2C_TWI.LBX" 'Setting up i2c hardware bus
Config Twi = 400000  'Hardware i2c bus speed
Config Scl = Portd.0 'TWI (i2c) ports on the Mega128
Config Sda = Portd.1
Const Addressw = &B10100000 'slave write address eeprom
Const Addressr = &B10100001 'slave read address eeprom


Dim Startbyte As Byte , Instring As String * 45 , Complete As Bit
Dim Temp As Byte , Temps As String * 3
Dim Bytecount As Byte , Addresshigh As Byte , Addresslow As Byte , Recordtype As Byte , Databyte(16) As Byte , Checksm As Byte
Dim Lus As Byte , Pos As Byte , Checksum_calc As Byte , Checksum_error As Bit

Enable Urxc
Enable Interrupts
On Urxc Bytereceived_isr


'=== Main ===
Do
If Complete = 1 Then  'Wait until the buffer is filled with one line
 Gosub Process_buffer 'Process the buffer
 Gosub Calculate_checksum 'Calculate the cheksum
 If Recordtype = &H01 Then  'EOF finished, send a ACK and return
 Print "Y";
 Else
 If Checksum_error = 0 Then 'If there's no error continue
 Select Case Recordtype 'do something with the recordtype
 Case &H00 'Data byte
 Gosub Prog_eeprom 'Recordtype &H00 = databyte, so lets programm the Eeprom
 Case &H02  'Extended Linear Address Records, not (yet) supported
 nop
 End Select
 Print "Y"; 'Checksum ok, send a ACK
 Else
 Print "Z";  'Checksum error send a Nack
 End If
 End If
 Complete = 0 : Instring = "" 'Reset the variable
End If
Loop
End


'=== Subroutines ===
Prog_eeprom:
 I2cstart 'start condition
 I2cwbyte Addressw 'slave address
 I2cwbyte Addresshigh 'Highaddress of EEPROM
 I2cwbyte Addresslow 'Lowaddress of EEPROM
   For Lus = 1 To Bytecount
    I2cwbyte Databyte(lus) 'value to write
  Next Lus
 I2cstop 'stop condition
 Waitms 10 'wait for 10 milliseconds
Return


Process_buffer:
Temps = Mid(instring , 1 , 2) : Bytecount = Hexval(temps) 'Read the numbers of bytes
Temps = Mid(instring , 3 , 2) : Addresshigh = Hexval(temps) 'Read the high adress
Temps = Mid(instring , 5 , 2) : Addresslow = Hexval(temps) 'Read the low adress
Temps = Mid(instring , 7 , 2) : Recordtype = Hexval(temps) 'Read the recordtype
For Lus = 1 To Bytecount 'Process the number of data bytes
 Pos = Lus * 2
 Pos = Pos + 7
 Temps = Mid(instring , Pos , 2) : Databyte(lus) = Hexval(temps) 'Read the databytes
Next Lus
Pos = Pos + 2 'read the last byte
Temps = Mid(instring , Pos , 2) : Checksm = Hexval(temps) 'Read checksum
Return


Calculate_checksum:
Temp = 0 'Add up all the databytes
Temp = Temp + Bytecount
Temp = Temp + Addresshigh
Temp = Temp + Addresslow
Temp = Temp + Recordtype
 For Lus = 1 To Bytecount
 Temp = Temp + Databyte(lus)
 Next Lus
Checksum_calc = 256 - Temp 'taking its two's complement
 If Checksum_calc <> Checksm Then 'Compare it with the readed value
 Checksum_error = 1
 Else
 Checksum_error = 0
 End If
Return

Bytereceived_isr:
Temp = Udr 'get the binary value that came across
If Temp = &H0D Then 'Received CR = end of line, line complete
 If Len(instring) < 8 Then 'To short, startover again
 Complete = 0
 Instring = ""
 Else
 Complete = 1 'String is complete set the flag
 End If
End If

If Startbyte = &H3A Then  'we have previously received the start byte and this is now data
 If Temp > &H0F Then 'Add incoming data to buffer
 Instring = Instring + Chr(temp)
 If Len(instring) > 45 Then Instring = "" 'String is to long, reset and startover again
 End If
End If

If Temp = &H3A Then 'if we received an : then its the beginning of an new line.
 Startbyte = Temp
 Complete = 0
 Instring = ""
End If
Return