X5045是一種集看門狗、電壓監(jiān)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(yīng)用在需要少量存儲(chǔ)器,并對(duì)電路板空間需求較高場(chǎng)合,

X5045具有電壓監(jiān)控功能,可以保護(hù)系統(tǒng)免受低電壓的影響，當(dāng)電源電壓降到允許范圍(4.2V)以下時(shí)，系統(tǒng)將復(fù)位，直到電源電壓返回到穩(wěn)定值為止。X5045的存儲(chǔ)器與CPU 通過(guò)串行通信方式接口(SPI)，可以存放512個(gè)字節(jié)數(shù)據(jù).可擦寫(xiě)100萬(wàn)次,數(shù)據(jù)可保存100年.

下圖是X5045與具有手動(dòng)復(fù)位的8051微控制器的連接

注意：圖上的芯片寫(xiě)著是X5043，實(shí)際上這是X5045的接法

下邊是51讀寫(xiě)x5045存儲(chǔ)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(xiě)入使能指令(WREN)
#define WRDI 0x04 // 寫(xiě)入禁止指令(WRDI)
#define WRSR 0x01 // 寫(xiě)入狀態(tài)寄存器指令(WRSR)
#define RDSR 0x05 // 讀取狀態(tài)寄存器指令(RDSR)
#define WRITE 0x02 // 寫(xiě)入存儲(chǔ)器指令(WRITE)
#define READ 0x03 // 讀取存儲(chǔ)器指令(READ)
??????????????????????
#define STATUS_REG 0x00 // 要寫(xiě)入到狀態(tài)寄存器的值
#define MAX_POLL 0x99 // 最在查詢次數(shù)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(gè)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(xiě)入使能指令
????? CS = 1;
}????????????

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

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

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

void wrsr_cmd()
{
????? CS = 0;
????? outbyt(WRSR); // 傳送狀態(tài)寄存器寫(xiě)入指令
????? outbyt(STATUS_REG); // 傳送要寫(xiě)入的數(shù)據(jù)
????? CS = 1;
???? wip_poll(); // 檢測(cè)寫(xiě)入進(jìn)度
}

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

CS = 1;
?????? wip_poll(); // 檢測(cè)寫(xiě)入進(jìn)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(jié)

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

TH1 = 0xFD;??? // 波特率9600
????? TL1 = 0xFD;
?????? SCON = 0x50;?? // 設(shè)定串行口工作方式
?????? PCON &= 0xef;?? // 波特率不倍增
?????? TR1 = 1;??? // 啟動(dòng)定時(shí)器1
}
void send_char_com(unsigned char ch)
{ //向串口發(fā)送一個(gè)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(xiě)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);}

}