24FC256 I2C running at 1 Mhz?

[Jberg]

Hello,

Can this work, a 24FC256 EEPROM + PIC18F14K22 at 64 Mhz
an the i2c set at 1 Mhz to read EEPROM records ?

Here's what AI replied for the I2C setup.

' Configure High-Speed Hardware I2C Master Mode
' For PIC18F14K22: SCL is Pin 11 (RB6), SDA is Pin 10 (RB4)

' #define HI2C_BAUD_RATE 1000 ' Set I2C bus speed to Ultra-Fast Mode (1 MHz / 1000 kHz)
' #define HI2C_DATA PORTB.4
' #define HI2C_CLOCK PORTB.6
HI2CMode Master

Thanks for any advices

[Anobium]

I would look at the demos to check.

[Jberg]

Basicaly the project use Holtek HT9032D FSK, a 24FC256 EEPROM + PIC18F14K22 at 64 Mhz
if the make sense then I'll setup the parts on PCB, and start experimenting

AI suggestion: (GCBASIC Code with 24FC256 1 MHz I2C Integration)

'---------------------------------------------------------------------
' GCBASIC Caller ID Whitelist via High-Speed 24FC256 EEPROM (PIC18F14K22)
'---------------------------------------------------------------------
#chip 18F14K22, 64        ' Run PIC at 64 MHz max internal clock
#config FamilyOsc = IRC   ' Set internal oscillator block with 4x PLL

' Define Hardware Pins for 20-Pin Package
#define HT_DOUT PORTB.5   ' Hardware UART RX Pin from HT9032D DOUT (Pin 13)
#define RELAY_PIN PORTC.0 ' Output pin to trigger relay/gate lock (Pin 16)

Dir HT_DOUT In
Dir RELAY_PIN Out
RELAY_PIN = 0             ' Default off

' Configure Hardware UART1 for HT9032D (1200 Baud, 8-N-1)
#define USART_BAUD_RATE 1200
#define USART_TX_BLOCKING
#define USART_DELAY 0

' Configure High-Speed Hardware I2C Master Mode 
' For PIC18F14K22: SCL is Pin 11 (RB6), SDA is Pin 10 (RB4)
#define HI2C_BAUD_RATE 1000 ' Set I2C bus speed to Ultra-Fast Mode (1 MHz / 1000 kHz)
#define HI2C_DATA PORTB.4
#define HI2C_CLOCK PORTB.6
HI2CMode Master

' 24FC256 Hardware I2C Target Address (Assuming A0, A1, A2 pins are grounded)
#define EEPROM_ADDRESS 160 ' 0xA0 in decimal representation

' Memory Sizing Limits
#define TOTAL_RECORDS 100  ' Can expand up to 2978 records on a 24FC256
#define RECORD_SIZE 11

' Global Buffers and Counters
Dim IncomingBuffer As String * 11
Dim CurrentByte As Byte
Dim DigitCount As Byte
DigitCount = 0

' Main Program Loop
Do
  ' Check if hardware UART has received a byte from the HT9032D
  If USARTHasData Then
    HSerReceive CurrentByte

    ' Extract numerical phone digits ('0' to '9')
    If CurrentByte >= 48 Then
      If CurrentByte <= 57 Then
        If DigitCount < RECORD_SIZE Then
          Mid(IncomingBuffer, DigitCount + 1, 1) = Chr(CurrentByte)
          DigitCount = DigitCount + 1
        End If
      End If
    Else
      ' End of FSK packet detected (Non-numeric delimiter byte)
      If DigitCount >= 10 Then

        ' Perform the high-speed external I2C search loop
        If SearchWhitelist(IncomingBuffer) Then
          RELAY_PIN = 1   ' ACCESS GRANTED
          Wait 3 s
          RELAY_PIN = 0
        Else
          RELAY_PIN = 0   ' ACCESS DENIED
        End If

        ' Reset memory registers for next call
        IncomingBuffer = ""
        DigitCount = 0
      End If
    End If
  End If
Loop

'---------------------------------------------------------------------
' High-Level Function: Read an 11-Byte Record from the 24FC256 at 1 MHz
'---------------------------------------------------------------------
Sub GetStoredNumber(In RecordIndex As Word, Out NumberOut As String)
  Dim StartByteOffset As Word
  Dim AddressHigh As Byte
  Dim AddressLow As Byte
  Dim CharPosition As Byte
  Dim DataByte As Byte

  ' Calculate 16-bit address offsets cleanly without bitwise operators
  StartByteOffset = (RecordIndex - 1) * RECORD_SIZE

  ' Separate the 16-bit word address into high and low bytes natively using GCBASIC system helpers
  AddressHigh = StartByteOffset_H
  AddressLow = StartByteOffset_L

  NumberOut = "           " ' Clear buffer space

  ' Execute an I2C random read burst block sequentially
  HI2CStart
  HI2CSend EEPROM_ADDRESS
  HI2CSend AddressHigh
  HI2CSend AddressLow

  HI2CReStart
  HI2CSend EEPROM_ADDRESS + 1 ' Read Mode Command Flag

  For CharPosition = 1 To RECORD_SIZE
    ' Fetch byte and handle I2C Acknowledgement natively
    If CharPosition = RECORD_SIZE Then
      HI2CReceive DataByte, False ' Send NACK on final byte to close stream
    Else
      HI2CReceive DataByte, True  ' Send ACK to continue reading sequential bytes
    End If
    Mid(NumberOut, CharPosition, 1) = Chr(DataByte)
  Next
  HI2CStop
End Sub

'---------------------------------------------------------------------
' High-Level Function: Add / Append a New Phone Number into the 24FC256
'---------------------------------------------------------------------
Sub AddPhoneNumber(In NewNumber As String)
  Dim SearchIndex As Word
  Dim TargetIndex As Word
  Dim CheckStr As String * 11
  Dim WriteOffset As Word
  Dim AddressHigh As Byte
  Dim AddressLow As Byte
  Dim CharIndex As Byte
  Dim AsciiVal As Byte

  TargetIndex = 0

  ' 1. Find the first empty memory cell block
  For SearchIndex = 1 To TOTAL_RECORDS
    GetStoredNumber(SearchIndex, CheckStr)

    ' Fresh or erased external EEPROM memory addresses return 255
    If Asc(CheckStr) = 255 Then
      TargetIndex = SearchIndex
      Exit For
    End If

    ' Duplicate checking parameter
    If CheckStr = NewNumber Then
      Exit Sub
    End If
  Next

  ' 2. If a vacant slot exists, execute an optimized Page Write sequence
  If TargetIndex > 0 Then
    WriteOffset = (TargetIndex - 1) * RECORD_SIZE
    AddressHigh = WriteOffset_H
    AddressLow = WriteOffset_L

    HI2CStart
    HI2CSend EEPROM_ADDRESS
    HI2CSend AddressHigh
    HI2CSend AddressLow

    ' Stream the 11 characters directly into the 24FC256 internal page buffer
    For CharIndex = 1 To RECORD_SIZE
      AsciiVal = Asc(Mid(NewNumber, CharIndex, 1))
      HI2CSend AsciiVal
    Next
    HI2CStop

    ' The 24FC256 takes up to 5ms to process a page write internally. 
    ' This delay ensures the chip is completely done writing.
    Wait 5 ms 
  End If
End Sub

'---------------------------------------------------------------------
' High-Level Search Engine
'---------------------------------------------------------------------
Function SearchWhitelist(TargetNumber As String) As Bit
  Dim RecordIndex As Word
  Dim StoredNumber As String * 11

  SearchWhitelist = 0 ' Default fail condition

  For RecordIndex = 1 To TOTAL_RECORDS
    GetStoredNumber(RecordIndex, StoredNumber)

    If StoredNumber = TargetNumber Then
      SearchWhitelist = 1 ' Match detected
      Exit Function
    End If
  Next
End Function

[Anobium]

It will not compile but give it a go. When you get an error.. and you will, find the line and press F1, then, do a search to help to resolve the error.

I would instrument the code to send serial out to a terminal to see what is happening.

[Jberg]

I'll give it a try.
Thanks, for the inside.

[Jerry Messina]

You'll likely have a hard time getting the I2C hardware in the K22 to actually provide 1MHz operation, especially if using resistor pullups... the risetimes are just too slow.

You could try using active rise-time accelerators to speed things up, but even with those I could never get much more than 800KHz to work reliably with the K22. The MSSP samples the signals too quickly and generates false bus collisions.

[Anobium]

The AI may be incorrect with the operating frequency of the bus. So, proove the circuitry first at a lower frequecy.