X5045是一種集看門狗、電壓監控和串行EEPROM 三種功能于一身的可編程控制電路.特別適合應用在需要少量存儲器,并對電路板空間需求較高場合,

X5045具有電壓監控功能,可以保護系統免受低電壓的影響，當電源電壓降到允許范圍(4.2V)以下時，系統將復位，直到電源電壓返回到穩定值為止。X5045的存儲器與CPU 通過串行通信方式接口(SPI)，可以存放512個字節數據.可擦寫100萬次,數據可保存100年.

下圖是X5045與具有手動復位的8051微控制器的連接

注意：圖上的芯片寫著是X5043，實際上這是X5045的接法

下邊是51讀寫x5045存儲器的程序

//x5045和51的連接方法
sbit CS = P1^0;
sbit SO = P1^3;
sbit SI = P1^1;
sbit SCK = P1^2;
//定義寄存器指令
#define WREN 0x06 // 寫入使能指令(WREN)
#define WRDI 0x04 // 寫入禁止指令(WRDI)
#define WRSR 0x01 // 寫入狀態寄存器指令(WRSR)
#define RDSR 0x05 // 讀取狀態寄存器指令(RDSR)
#define WRITE 0x02 // 寫入存儲器指令(WRITE)
#define READ 0x03 // 讀取存儲器指令(READ)
??????????????????????
#define STATUS_REG 0x00 // 要寫入到狀態寄存器的值
#define MAX_POLL 0x99 // 最在查詢次數m number of

void outbyte(unsigned char write_data)
{
???? unsigned char i;
????? for(i = 0; i < 8; i++)
????? {
????? SCK = 0;
????? SI = (bit)(write_data & 0x80); //傳送一個位到SI
????? write_data <<= 1;
???? SCK = 1;
????? }
????? SI = 0;
}
unsigned char inbyte()
{
????? unsigned char i;
????? unsigned char read_data=0;

for(i = 0; i < 8; i++)
????? {
???????? SCK = 0;
???????? read_data <<= 1;
???????? SCK = 1;
???????? read_data |= (unsigned char)SO;
????? }
????? return read_data;
}

void wren_cmd()
{

????? CS = 0;??????????
????? outbyt(WREN); // 傳送寫入使能指令
????? CS = 1;
}????????????

void wrdi_cmd()
{
???? CS = 0;??????????
???? outbyt(WRDI); // 傳送寫入禁止指令
???? CS = 1;
}

unsigned char rdsr_cmd()
{
?????? unsigned char status;
?????? CS = 0;???
?????? outbyt(RDSR); // 傳送狀態寄存器讀取指令
?????? status = inbyt(); // 讀取狀態寄存
?????? CS = 1;
?????? return status;
}
void wip_poll()
{
?? unsigned char i; // 設置最大的查詢次數

//// 如果WIP位為'1'并且未達到最大查詢次數, 則繼續查詢
//// 如果WIP位為'0', 則寫入周期完成, 返回
?? for(i = 0; i < MAX_POLL; i++)
?? {
????? if(rdsr_cmd() & 0x01) // 讀取狀態寄存器
????? {
??????? continue;
????? }
????? return;
??? }
}

void wrsr_cmd()
{
????? CS = 0;
????? outbyt(WRSR); // 傳送狀態寄存器寫入指令
????? outbyt(STATUS_REG); // 傳送要寫入的數據
????? CS = 1;
???? wip_poll(); // 檢測寫入進度
}

void byte_write(unsigned int addr,unsigned char dat)
{
????? wren_cmd();
???? CS = 0;
????? if(addr & 0x100)
????????? outbyt(WRITE | 0x08); //傳送寫入指令和地址最高位"1"
????? else
?????????? outbyt(WRITE); // 傳送寫入指令和地址最高位"0"
???? outbyt(addr); // 傳送地址低字節?????
????? outbyt(dat); // 傳送數據字節??

CS = 1;
?????? wip_poll(); // 檢測寫入進度
}
unsigned char byte_read(unsigned int addr)
{
?????? unsigned char read_data;
??????? CS = 0;??
?????? if(addr & 0x100)
??????????? outbyt(READ | 0x08);// 傳送讀取指令和地址最高位"1"
??????? else????
????????? outbyt(READ); // 傳送讀取指令和地址最高位"0"
???????

outbyt(addr); // 傳送地址低字節

read_data = inbyt(); // 讀取字節
?????? CS = 1;
??????? return read_data;
}
void rst_wdog()
{
??? CS = 0;
??? _nop_();_nop_();
??? CS = 1;
}
void init_serialcomm(void)
{?? TMOD = 0x21;?? // 定時器1工作于8位自動重載模式, 用于產生波特率
????????? // 定時器0工作于16位模式, 用于定時

TH1 = 0xFD;??? // 波特率9600
????? TL1 = 0xFD;
?????? SCON = 0x50;?? // 設定串行口工作方式
?????? PCON &= 0xef;?? // 波特率不倍增
?????? TR1 = 1;??? // 啟動定時器1
}
void send_char_com(unsigned char ch)
{ //向串口發送一個字符
?? SBUF=ch;
?? while(!TI);
?? TI=0;
}

void main(void)
{
???????? unsigned char Temp,tdat;??????????????????

init_serialcomm();
?????? while(1)
????? {
?????????? //這里演示讀出和寫入 EEPROM???

?? for (Temp=0; Temp<250; Temp++)?? byte_write(Temp,Temp);
???????? delay(200);

?? for (Temp=0; Temp<250; Temp++)

{ tdat= byte_read(Temp); send_char_com(tdat);}

}