Question

前言：这个问题是关于我和我大学教授合作的一个项目。这不是一个年级，但我对这位教授的声誉确实很重要。虽然我在这个项目上的成功对我很重要，但我认为从Stack Overflow寻求帮助并不公平。

那就是说，这是我项目的高级概述。我有一个ATmega328微控制器。我有一个Microchip SST 64 Mbit闪存卡。 ATmega具有SPI的硬件实现。闪存具有SPI的硬件实现。

我的目标是使用SPI主模式下的ATmega从闪存芯片读取数据并将数据写入闪存芯片。内存采用多重覆盖结构，非常适合擦除，但就我的目的而言，它基本上只有32,768页，每页256字节。

写数据的基本思路是我发送一个指令字节，然后是起始地址，然后是数据。要读取数据的基本思想是我发送一个指令字节，然后是起始地址，然后是一个虚拟字节，然后它开始向我发送数据。

以下是数据表：

微控制器：http://www.atmel.com/dyn/resources/prod_documents/doc8271.pdf

Flash：http://www.sst.com/dotAsset/40498.pdf

代码：

#include <SPI.h>
#include <Peggy2.h>

#define SS_PIN  16

Peggy2 frame1;
byte toDisp = 0;
byte checker = 0;

void setup()
{
    frame1.HardwareInit();
    pinMode(SS_PIN,OUTPUT); //set pin16 to output, SS pin
    SPI.setClockDivider(SPI_CLOCK_DIV2); //set the SPI clock to f/2, fastest possible
    SPI.begin();    //SPI lib function which sets ddr for SCK and MOSI pin
                    //MISO is auto input
                    //see SPI.cpp for more info

}

void loop()
{

    if(!checker){
                enableProgramming();
        programData();
        toDisp = receiveByte(0);
        checker = 1;
        frame1.WriteRow(0,toDisp);
    }
    frame1.RefreshAll(2);

}

byte receiveByte(unsigned long startAddress)
{
    //Begin High Speed Read Instruction
    //See p. 10 of SST data sheet
    digitalWrite(SS_PIN,LOW);
    SPI.transfer(0x0B); //high speed read instruction
    SPI.transfer(0x00); //next 3 transfers are address bits A32 - A0
    SPI.transfer(0x00); //So this will read the first byte on the chip
    SPI.transfer(0x00); //last address bits
    SPI.transfer(0xFF); //dummy byte is required to start sending data back to uP
    SPI.transfer(0xFF); //I'm hoping that if I transfer a bullshit byte, the flash
                        //chip will transfer it's data to me in the same time
    digitalWrite(SS_PIN,HIGH);
    //End High Speed Read Instruction   
    return SPDR;    
}

//will perform the read instruction starting from
//startAddress and will receive numOfBytes bytes in
//succession
void receiveBytes(int numOfBytes, unsigned long startAddress)
{
    digitalWrite(SS_PIN,LOW);
    SPI.transfer(0x0B);//high speed read instruction

}

//will perform:
// 1) Chip Erase
// and loop through:
// 1) Page Program
// 2) increment Page
//until the data has finished **note this can loop and over write beginning of memory
void programData(){
    //Begin ChipErase Instruction
    //See p. 17 of SST data sheet
    digitalWrite(SS_PIN,LOW);
    SPI.transfer(0x60);//chip erase instruction
    digitalWrite(SS_PIN,HIGH);
    delay(50);//spec'd time for CE to finish
                //don't bother polling because time to program is irrelevant
    //End ChipErase Instruction

        //Begin WREN Instruction
    //See p. 18 of SST data sheet
    digitalWrite(SS_PIN,LOW);
    SPI.transfer(0x06);//write enable instruction
    digitalWrite(SS_PIN,HIGH);
    //End WREN Instruction

    digitalWrite(SS_PIN,LOW);
    SPI.transfer(0x02); //page program instruction
    SPI.transfer(0x00); //first 8 address bits
    SPI.transfer(0x00); //2nd 8 address bits
    SPI.transfer(0x00); //3rd 8 address bits
    SPI.transfer(0xAA); //10101010 is the byte I should be writing
    digitalWrite(SS_PIN,HIGH);
    delayMicroseconds(3000); //wait 3 ms for page program


    /*
    //Begin Page-Program Instruction
    //see p. 13 of SST data sheet
    byte firstAddress = 0;
    byte secondAddress = 0;
    //this loop will write to every byte in the chips memory
    //32,768 pages of 256 bytes = 8,388,608 bytes
    for(unsigned int i = 0; i < 32,768; ++i) //long variable is number of pages
    {
        digitalWrite(SS_PIN,LOW);
        ++secondAddress; //cycles from 0 to 255, counts pages
        firstAddress = i>>8; // floor(i/256)

        SPI.transfer(0x02);//Page-Program instruction byte
        SPI.transfer(firstAddress); //increments every 256 pages i.e. at page 256 this should be 1
        SPI.transfer(secondAddress); //increments every 256 bytes, i.e every page
        SPI.transfer(0x00); //beginning of a page boundary
        for(int j = 0; j < 256; ++j) //number of bytes per page
        {
            SPI.transfer(2program[(256*i) + j]);//data byte transfer            
        }
        digitalWrite(SS_PIN,HIGH);
        delayMicroseconds(2500); //2500us (2.5ms) delay for each page-program instruction to execute
    }
    //End Page-Program Instruction
    */
}

//Will prepare the chip for writing by performing:
// 1) arm the status register
// 2) Write Enable instruction
//Only needs to be performed once!
void enableProgramming(){
    //Begin EWSR & WRSR Instructions
    //See p. 20 of SST data sheet for more info
    digitalWrite(SS_PIN,LOW); //lower the SS pin
    SPI.transfer(0x50); //enable write status register instruction
    digitalWrite(SS_PIN,HIGH); //raise the SS pin
    delay(10);
    digitalWrite(SS_PIN,LOW); //lower the SS pin
    SPI.transfer(0x01); //write the status register instruction
    SPI.transfer(0x00);//value to write to register
                //xx0000xx will remove all block protection
    digitalWrite(SS_PIN,HIGH);
    //End EWSR & WRSR Instructions

    //Begin WREN Instruction
    //See p. 18 of SST data sheet
    digitalWrite(SS_PIN,LOW);
    SPI.transfer(0x06);//write enable instruction
    digitalWrite(SS_PIN,HIGH);
    //End WREN Instruction

}

所以这应该是一个测试程序，它将1个字节编程到闪存上，然后将其读回并在我拥有的LED阵列上显示该字节。如果您对LED阵列感兴趣，可以在此处找到：http://evilmadscience.com/tinykitlist/157

我相信我的读取功能有效，因为我第一次运行它时，所有8个LED都亮了。这将告诉我，当它处于所有1的工厂状态时，它会读取闪存。现在显然我已经搞砸了写作，因为点亮的字节与我正在尝试编程的字节完全不对应。

我还应该注意到我正在使用Arduinos的默认SPI库，并且帧缓冲功能正常工作。当我frame1.WriteRow(toDisp)时，它正常工作并经过广泛测试。

如果有人有时间或耐心去弄清楚我做错了什么会非常棒。

编辑：帮助调试：
LED也由使用SPI接口的驱动芯片驱动。我没有写那部分代码。在示波器上，我可以看到SCK线由该部分代码驱动。但是，我也对MOSI引脚进行了探测，如果我没有点亮任何灯，它似乎永远不会变高。对我而言，这意味着我没有正确发送信息。 AKA ...也许我的SPI.transfer()需要启用功能或什么？

Answer 1

对于任何仍然感到好奇的人来说，问题在于内存芯片对缓慢的上升时间非常敏感。在投入施密特触发器之后，一切都运转良好。

ATmega328 + SPI闪存

1 个答案: