// ******************************************************************************************************* // ** ** // ** 24LC04B.v - Microchip 24LC04B 4K-BIT I2C SERIAL EEPROM (VCC = +2.5V TO +5.5V) ** // ** ** // ******************************************************************************************************* // ** ** // ** This information is distributed under license from Young Engineering. ** // ** COPYRIGHT (c) 2003 YOUNG ENGINEERING ** // ** ALL RIGHTS RESERVED ** // ** ** // ** ** // ** Young Engineering provides design expertise for the digital world ** // ** Started in 1990, Young Engineering offers products and services for your electronic design ** // ** project. We have the expertise in PCB, FPGA, ASIC, firmware, and software design. ** // ** From concept to prototype to production, we can help you. ** // ** ** // ** http://www.young-engineering.com/ ** // ** ** // ******************************************************************************************************* // ** This information is provided to you for your convenience and use with Microchip products only. ** // ** Microchip disclaims all liability arising from this information and its use. ** // ** ** // ** THIS INFORMATION IS PROVIDED "AS IS." MICROCHIP MAKES NO REPRESENTATION OR WARRANTIES OF ** // ** ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO ** // ** THE INFORMATION PROVIDED TO YOU, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, ** // ** PERFORMANCE, MERCHANTABILITY, NON-INFRINGEMENT, OR FITNESS FOR PURPOSE. ** // ** MICROCHIP IS NOT LIABLE, UNDER ANY CIRCUMSTANCES, FOR SPECIAL, INCIDENTAL OR CONSEQUENTIAL ** // ** DAMAGES, FOR ANY REASON WHATSOEVER. ** // ** ** // ** It is your responsibility to ensure that your application meets with your specifications. ** // ** ** // ******************************************************************************************************* // ** Revision : 1.3 ** // ** Modified Date : 12/04/2006 ** // ** Revision History: ** // ** ** // ** 02/01/2003: Initial design ** // ** 07/19/2004: Fixed the timing checks and the open-drain modeling for SDA. ** // ** 01/06/2006: Changed the legal information in the header ** // ** 12/04/2006: Corrected timing checks to reference proper clock edges ** // ** Added timing check for Tbuf (bus free time) ** // ** ** // ******************************************************************************************************* // ** TABLE OF CONTENTS ** // ******************************************************************************************************* // **---------------------------------------------------------------------------------------------------** // ** DECLARATIONS ** // **---------------------------------------------------------------------------------------------------** // **---------------------------------------------------------------------------------------------------** // ** INITIALIZATION ** // **---------------------------------------------------------------------------------------------------** // **---------------------------------------------------------------------------------------------------** // ** CORE LOGIC ** // **---------------------------------------------------------------------------------------------------** // ** 1.01: START Bit Detection ** // ** 1.02: STOP Bit Detection ** // ** 1.03: Input Shift Register ** // ** 1.04: Input Bit Counter ** // ** 1.05: Control Byte Register ** // ** 1.06: Byte Address Register ** // ** 1.07: Write Data Buffer ** // ** 1.08: Acknowledge Generator ** // ** 1.09: Acknowledge Detect ** // ** 1.10: Write Cycle Timer ** // ** 1.11: Write Cycle Processor ** // ** 1.12: Read Data Multiplexor ** // ** 1.13: Read Data Processor ** // ** 1.14: SDA Data I/O Buffer ** // ** ** // **---------------------------------------------------------------------------------------------------** // ** DEBUG LOGIC ** // **---------------------------------------------------------------------------------------------------** // ** 2.01: Memory Data Bytes ** // ** 2.02: Write Data Buffer ** // ** ** // **---------------------------------------------------------------------------------------------------** // ** TIMING CHECKS ** // **---------------------------------------------------------------------------------------------------** // ** ** // ******************************************************************************************************* `timescale 1ns/10ps module M24LC04B (A0, A1, A2, WP, SDA, SCL, RESET); input A0; // unconnected pin input A1; // unconnected pin input A2; // unconnected pin input WP; // write protect pin inout SDA; // serial data I/O input SCL; // serial data clock input RESET; // system reset // ******************************************************************************************************* // ** DECLARATIONS ** // ******************************************************************************************************* reg SDA_DO; // serial data - output reg SDA_OE; // serial data - output enable wire SDA_DriveEnable; // serial data output enable reg SDA_DriveEnableDlyd; // serial data output enable - delayed wire [02:00] ChipAddress; // hardwired chip address reg [03:00] BitCounter; // serial bit counter reg START_Rcvd; // START bit received flag reg STOP_Rcvd; // STOP bit received flag reg CTRL_Rcvd; // control byte received flag reg ADDR_Rcvd; // byte address received flag reg MACK_Rcvd; // master acknowledge received flag reg WrCycle; // memory write cycle reg RdCycle; // memory read cycle reg [07:00] ShiftRegister; // input data shift register reg [07:00] ControlByte; // control byte register wire BlockSelect; // memory block select wire RdWrBit; // read/write control bit reg [08:00] StartAddress; // memory access starting address reg [03:00] PageAddress; // memory page address reg [07:00] WrDataByte [0:15]; // memory write data buffer wire [07:00] RdDataByte; // memory read data reg [15:00] WrCounter; // write buffer counter reg [03:00] WrPointer; // write buffer pointer reg [08:00] RdPointer; // read address pointer reg WriteActive; // memory write cycle active reg [07:00] MemoryBlock0 [0:255]; // EEPROM data memory array reg [07:00] MemoryBlock1 [0:255]; // EEPROM data memory array integer LoopIndex; // iterative loop index integer tAA; // timing parameter integer tWC; // timing parameter // ******************************************************************************************************* // ** INITIALIZATION ** // ******************************************************************************************************* initial tAA = 900; // SCL to SDA output delay initial tWC = 5000000; // memory write cycle time initial begin SDA_DO = 0; SDA_OE = 0; end initial begin START_Rcvd = 0; STOP_Rcvd = 0; CTRL_Rcvd = 0; ADDR_Rcvd = 0; MACK_Rcvd = 0; end initial begin BitCounter = 0; ControlByte = 0; end initial begin WrCycle = 0; RdCycle = 0; WriteActive = 0; end assign ChipAddress = {A2,A1,A0}; // ******************************************************************************************************* // ** CORE LOGIC ** // ******************************************************************************************************* // ------------------------------------------------------------------------------------------------------- // 1.01: START Bit Detection // ------------------------------------------------------------------------------------------------------- always @(negedge SDA) begin if (SCL == 1) begin START_Rcvd <= 1; STOP_Rcvd <= 0; CTRL_Rcvd <= 0; ADDR_Rcvd <= 0; MACK_Rcvd <= 0; WrCycle <= #1 0; RdCycle <= #1 0; BitCounter <= 0; end end // ------------------------------------------------------------------------------------------------------- // 1.02: STOP Bit Detection // ------------------------------------------------------------------------------------------------------- always @(posedge SDA) begin if (SCL == 1) begin START_Rcvd <= 0; STOP_Rcvd <= 1; CTRL_Rcvd <= 0; ADDR_Rcvd <= 0; MACK_Rcvd <= 0; WrCycle <= #1 0; RdCycle <= #1 0; BitCounter <= 10; end end // ------------------------------------------------------------------------------------------------------- // 1.03: Input Shift Register // ------------------------------------------------------------------------------------------------------- always @(posedge SCL) begin ShiftRegister[00] <= SDA; ShiftRegister[01] <= ShiftRegister[00]; ShiftRegister[02] <= ShiftRegister[01]; ShiftRegister[03] <= ShiftRegister[02]; ShiftRegister[04] <= ShiftRegister[03]; ShiftRegister[05] <= ShiftRegister[04]; ShiftRegister[06] <= ShiftRegister[05]; ShiftRegister[07] <= ShiftRegister[06]; end // ------------------------------------------------------------------------------------------------------- // 1.04: Input Bit Counter // ------------------------------------------------------------------------------------------------------- always @(posedge SCL) begin if (BitCounter < 10) BitCounter <= BitCounter + 1; end // ------------------------------------------------------------------------------------------------------- // 1.05: Control Byte Register // ------------------------------------------------------------------------------------------------------- always @(negedge SCL) begin if (START_Rcvd & (BitCounter == 8)) begin if (!WriteActive & (ShiftRegister[07:01] == {4'b1010,ChipAddress[02:00]})) begin if (ShiftRegister[00] == 0) WrCycle <= 1; if (ShiftRegister[00] == 1) RdCycle <= 1; ControlByte <= ShiftRegister[07:00]; CTRL_Rcvd <= 1; end START_Rcvd <= 0; end end assign BlockSelect = ControlByte[01]; assign RdWrBit = ControlByte[00]; // ------------------------------------------------------------------------------------------------------- // 1.06: Byte Address Register // ------------------------------------------------------------------------------------------------------- always @(negedge SCL) begin if (CTRL_Rcvd & (BitCounter == 8)) begin if (RdWrBit == 0) begin StartAddress <= {BlockSelect,ShiftRegister[07:00]}; RdPointer <= {BlockSelect,ShiftRegister[07:00]}; ADDR_Rcvd <= 1; end WrCounter <= 0; WrPointer <= 0; CTRL_Rcvd <= 0; end end // ------------------------------------------------------------------------------------------------------- // 1.07: Write Data Buffer // ------------------------------------------------------------------------------------------------------- always @(negedge SCL) begin if (ADDR_Rcvd & (BitCounter == 8)) begin if ((WP == 0) & (RdWrBit == 0)) begin WrDataByte[WrPointer] <= ShiftRegister[07:00]; WrCounter <= WrCounter + 1; WrPointer <= WrPointer + 1; end end end // ------------------------------------------------------------------------------------------------------- // 1.08: Acknowledge Generator // ------------------------------------------------------------------------------------------------------- always @(negedge SCL) begin if (!WriteActive) begin if (BitCounter == 8) begin if (WrCycle | (START_Rcvd & (ShiftRegister[07:01] == {4'b1010,ChipAddress[02:00]}))) begin SDA_DO <= 0; SDA_OE <= 1; end end if (BitCounter == 9) begin BitCounter <= 0; if (!RdCycle) begin SDA_DO <= 0; SDA_OE <= 0; end end end end // ------------------------------------------------------------------------------------------------------- // 1.09: Acknowledge Detect // ------------------------------------------------------------------------------------------------------- always @(posedge SCL) begin if (RdCycle & (BitCounter == 8)) begin if ((SDA == 0) & (SDA_OE == 0)) MACK_Rcvd <= 1; end end always @(negedge SCL) MACK_Rcvd <= 0; // ------------------------------------------------------------------------------------------------------- // 1.10: Write Cycle Timer // ------------------------------------------------------------------------------------------------------- always @(posedge STOP_Rcvd) begin if (WrCycle & (WP == 0) & (WrCounter > 0)) begin WriteActive = 1; #(tWC); WriteActive = 0; end end always @(posedge STOP_Rcvd) begin #(1.0); STOP_Rcvd = 0; end // ------------------------------------------------------------------------------------------------------- // 1.11: Write Cycle Processor // ------------------------------------------------------------------------------------------------------- always @(negedge WriteActive) begin for (LoopIndex = 0; LoopIndex < WrCounter; LoopIndex = LoopIndex + 1) begin if (StartAddress[08] == 0) begin PageAddress = StartAddress[03:00] + LoopIndex; MemoryBlock0[{StartAddress[07:04],PageAddress[03:00]}] = WrDataByte[LoopIndex[03:00]]; end if (StartAddress[08] == 1) begin PageAddress = StartAddress[03:00] + LoopIndex; MemoryBlock1[{StartAddress[07:04],PageAddress[03:00]}] = WrDataByte[LoopIndex[03:00]]; end end end // ------------------------------------------------------------------------------------------------------- // 1.12: Read Data Multiplexor // ------------------------------------------------------------------------------------------------------- always @(negedge SCL) begin if (BitCounter == 8) begin if (WrCycle & ADDR_Rcvd) begin RdPointer <= StartAddress + WrPointer + 1; end if (RdCycle) begin RdPointer <= RdPointer + 1; end end end assign RdDataByte = RdPointer[08] ? MemoryBlock1[RdPointer[07:00]] : MemoryBlock0[RdPointer[07:00]]; // ------------------------------------------------------------------------------------------------------- // 1.13: Read Data Processor // ------------------------------------------------------------------------------------------------------- always @(negedge SCL) begin if (RdCycle) begin if (BitCounter == 8) begin SDA_DO <= 0; SDA_OE <= 0; end else if (BitCounter == 9) begin SDA_DO <= RdDataByte[07]; if (MACK_Rcvd) SDA_OE <= 1; end else begin SDA_DO <= RdDataByte[7-BitCounter]; end end end // ------------------------------------------------------------------------------------------------------- // 1.14: SDA Data I/O Buffer // ------------------------------------------------------------------------------------------------------- bufif1 (SDA, 1'b0, SDA_DriveEnableDlyd); assign SDA_DriveEnable = !SDA_DO & SDA_OE; always @(SDA_DriveEnable) SDA_DriveEnableDlyd <= #(tAA) SDA_DriveEnable; // ******************************************************************************************************* // ** DEBUG LOGIC ** // ******************************************************************************************************* // ------------------------------------------------------------------------------------------------------- // 2.01: Memory Data Bytes // ------------------------------------------------------------------------------------------------------- wire [07:00] MemoryByte0_00 = MemoryBlock0[00]; wire [07:00] MemoryByte0_01 = MemoryBlock0[01]; wire [07:00] MemoryByte0_02 = MemoryBlock0[02]; wire [07:00] MemoryByte0_03 = MemoryBlock0[03]; wire [07:00] MemoryByte0_04 = MemoryBlock0[04]; wire [07:00] MemoryByte0_05 = MemoryBlock0[05]; wire [07:00] MemoryByte0_06 = MemoryBlock0[06]; wire [07:00] MemoryByte0_07 = MemoryBlock0[07]; wire [07:00] MemoryByte0_08 = MemoryBlock0[08]; wire [07:00] MemoryByte0_09 = MemoryBlock0[09]; wire [07:00] MemoryByte0_0A = MemoryBlock0[10]; wire [07:00] MemoryByte0_0B = MemoryBlock0[11]; wire [07:00] MemoryByte0_0C = MemoryBlock0[12]; wire [07:00] MemoryByte0_0D = MemoryBlock0[13]; wire [07:00] MemoryByte0_0E = MemoryBlock0[14]; wire [07:00] MemoryByte0_0F = MemoryBlock0[15]; wire [07:00] MemoryByte1_00 = MemoryBlock1[00]; wire [07:00] MemoryByte1_01 = MemoryBlock1[01]; wire [07:00] MemoryByte1_02 = MemoryBlock1[02]; wire [07:00] MemoryByte1_03 = MemoryBlock1[03]; wire [07:00] MemoryByte1_04 = MemoryBlock1[04]; wire [07:00] MemoryByte1_05 = MemoryBlock1[05]; wire [07:00] MemoryByte1_06 = MemoryBlock1[06]; wire [07:00] MemoryByte1_07 = MemoryBlock1[07]; wire [07:00] MemoryByte1_08 = MemoryBlock1[08]; wire [07:00] MemoryByte1_09 = MemoryBlock1[09]; wire [07:00] MemoryByte1_0A = MemoryBlock1[10]; wire [07:00] MemoryByte1_0B = MemoryBlock1[11]; wire [07:00] MemoryByte1_0C = MemoryBlock1[12]; wire [07:00] MemoryByte1_0D = MemoryBlock1[13]; wire [07:00] MemoryByte1_0E = MemoryBlock1[14]; wire [07:00] MemoryByte1_0F = MemoryBlock1[15]; // ------------------------------------------------------------------------------------------------------- // 2.02: Write Data Buffer // ------------------------------------------------------------------------------------------------------- wire [07:00] WriteData_0 = WrDataByte[00]; wire [07:00] WriteData_1 = WrDataByte[01]; wire [07:00] WriteData_2 = WrDataByte[02]; wire [07:00] WriteData_3 = WrDataByte[03]; wire [07:00] WriteData_4 = WrDataByte[04]; wire [07:00] WriteData_5 = WrDataByte[05]; wire [07:00] WriteData_6 = WrDataByte[06]; wire [07:00] WriteData_7 = WrDataByte[07]; wire [07:00] WriteData_8 = WrDataByte[08]; wire [07:00] WriteData_9 = WrDataByte[09]; wire [07:00] WriteData_A = WrDataByte[10]; wire [07:00] WriteData_B = WrDataByte[11]; wire [07:00] WriteData_C = WrDataByte[12]; wire [07:00] WriteData_D = WrDataByte[13]; wire [07:00] WriteData_E = WrDataByte[14]; wire [07:00] WriteData_F = WrDataByte[15]; // ******************************************************************************************************* // ** TIMING CHECKS ** // ******************************************************************************************************* wire TimingCheckEnable = (RESET == 0) & (SDA_OE == 0); specify specparam tHI = 600, // SCL pulse width - high tLO = 1300, // SCL pulse width - low tSU_STA = 600, // SCL to SDA setup time tHD_STA = 600, // SCL to SDA hold time tSU_DAT = 100, // SDA to SCL setup time tSU_STO = 600, // SCL to SDA setup time tBUF = 1300; // Bus free time $width (posedge SCL, tHI); $width (negedge SCL, tLO); $width (posedge SDA &&& SCL, tBUF); $setup (posedge SCL, negedge SDA &&& TimingCheckEnable, tSU_STA); $setup (SDA, posedge SCL &&& TimingCheckEnable, tSU_DAT); $setup (posedge SCL, posedge SDA &&& TimingCheckEnable, tSU_STO); $hold (negedge SDA &&& TimingCheckEnable, negedge SCL, tHD_STA); endspecify endmodule