1-Wire EEPROM通信对存在脉冲作出响应

作为一个更新-我解决了引脚不被拉到“低”的EEPROM的问题-我必须配置在PIC上的端口引脚作为一个开放的排水管通过设置ODC寄存器。不确定是否需要启用弱上拉，因为我正在使用一个1K的外部上拉电阻。输出到序列号有一点变化，但我仍然没有看到0x43:0xFF0xFX0FFXXF0XX00X000 0X000 0XFE的家庭代码。



      以下为原文

    As an update - i solved the problem of the pin not being pulled to 'Low' by the EEPROM - i had to configure the port pin on the PIC as an open drain by setting the ODC register.  Not sure if i need to enable the weak pull-up as well since i am using an external pull up resistor of 1K.  The output to serial number changed a little, but still i don't see the family code of 0x43:
0xff
0xff
0xf0
0xff
0x00
0x00
0x00
0xfe
 
 
 
 
 
 

只增加1K可能会使附加芯片更难将它拉低到你需要的程度。在我看来最好使用4.7到10K。除非你以非常高的速率传输数据…



      以下为原文

    A pull-up of only 1K might make it harder for the attached chip to pull it as low as you need.
Better to use 4.7-10K in my opinion. Unless you are transferring data at extremely high rates of course...
 

除非我漏掉了一些东西，否则我看不出你在哪里用PIN线来输入PIN。为了模拟开路漏极信号，当需要从属线能够控制线路时，需要设置PIN TIS位高（OWApPixOne方向=输入）。



      以下为原文

    Unless I missed something, I don't see where you ever make the pin an input in onewire.c so you're always actively driving the pin high or low. To emulate an open-drain signal you need to set the pin TRIS bit high (OW_PIN_DIRECTION = INPUT) when you want the slave to be able to control the line.


unsigned char read_OW (void)
{
    unsigned char read_data=0;
        
    //OW_WRITE_PIN = INPUT;
    OW_PIN_DIRECTION = INPUT;
   
    // may need a slight delay here after changing the pin direction
    // to allow the pullup to slew to a high level
        
    if (HIGH == OW_READ_PIN)
        read_data = SET;
    else         
        read_data = CLEAR;
                
    return read_data;
}

B-是的，我把电阻换成2.1K电阻（EEPROM的数据表表示使用0.3K到2.2K的电阻）。从1K到2.2K的变化没有任何实际差异。杰瑞- PIN被更改为Read Type（）中的一个输入，这是从OWRADBITE（）调用的，它是从O中调用的。WiRead字节（）我附上了我的最新代码，它显示了打开漏极配置。我昨天继续工作，我发现在第一个数据字节的示波器上，我得到了正确的0x43的家庭代码。但我的软件只是作为0xFF阅读。我想知道PIC24F是否需要一段时间从一个输出引脚变成一个输入PUT？或者，当我改变PIN到一个输入时，我还需要改变开漏配置到0的PIN？未签署的Car Read Type（空）*前提：无*输入：无*输出：返回OW PIN的状态。*概述：配置为输入引脚，并读取OWSPIN ************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************



      以下为原文

    Bo - Yes, I changed the resistor back to a 2.1K resistor (the data sheet for the EEPROM says to use a resistor of 0.3k to 2.2K.  changing from 1K to 2.2K didn't make any practical difference.
 
Jerry - the pin is changed to an input in read_OW(), which is called from OWReadBit(), which is called from OWReadByte().  I attached my latest code that shows the open drain configuration added.  
 
I kept working on it yesterday and i found that on the oscilloscope in the first byte of data I am getting the correct family code of 0x43.  But my software is just reading it as 0xFF.  I am wondering if the PIC24F is taking a while to change from an output pin to an input put?  Or maybe when i change the pin to an input I also need to change the open drain config to 0 for that pin?
 
/**********************************************************************
* Function: unsigned char read_OW (void)
* PreCondition: None
* Input: None
* Output: Return the status of OW pin.
* Overview: Configure as Input pin and Read the status of OW_PIN
***********************************************************************/
char read_OW (void)
{
char read_data=0;

OW_WRITE_PIN = INPUT;
Nop();
if (HIGH == OW_READ_PIN)
read_data = SET;
else
read_data = CLEAR;

return read_data;
}
 
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FWW:当我用I2C设计一个EEPROM接口时，我不得不把它敲一下，因为我使用的PIC24有一些硅问题，使I2C模块不工作。但结果是一件好事，因为我得到了双向I2C总线的感觉。我最后做的是设置LAT位。对于总线0，永远不必再改变。然后在传输函数中，根据想要的状态切换总线线路的TIS位：0：TIS设置为活动输出1：TrIS设置为TraseTead用这个配置，我只需要在TIS寄存器位和时钟延迟上工作。我喜欢一种魅力，即使是在很高的比特率上。对于阅读，我有一个函数，它只读取对应于总线的输入状态。也许你可以做一些类似的事情。（别忘了把PIN设置为数字，如果它有任何模拟的可能性。）



      以下为原文

   
FWIW:
When I designed an EEPROM interface using I2C I had to bit-bang it because the PIC24 I used has some silicon problems that made the I2C module nonworking.
But it turned out to be a good thing because then I got the feel for the bidirectional I2C bus.
 
What I ended up doing was to set the LAT bit for the bus line to 0, never to be changed again.
Then in the transmission function I toggled the TRIS bit for the bus line depending on the wanted state:
0: TRIS set to active output
1: TRIS set to tristate
 
With this arrangement I only needed to work on the TRIS register bit and a clock delay.
It worked like a charm even at very high bit rates.
For reading I have a function that just reads the state of the input corresponding to the bus.
 
Maybe you could do something similar?
(And don't forget to set the pin as digital if it has any analog possibility.)

不，至少不是你在你的文章中显示的读写器（）。这个语句“OWAWORKEWEXPIN =输入”，并没有使PIN成为一个输入，它只是设置LATD1= 1查看我发布的版本（以及BobAGI写的）。要设置PIN到输入模式，必须设置StRISISD1＝1。



      以下为原文

   
No it's not, at least not what you're showing read_OW() does in your post.
 
The statement 'OW_WRITE_PIN = INPUT;' doesn't make the pin an input, it just sets LATD1 = 1
Look at the version I posted (and what BobAGI wrote). To set the pin to input mode you have to set
TRISD1 = 1

这里是示例代码FM我的BIT I2C文件：注意，发送1或0是通过写到TIS寄存器来完成的。



      以下为原文

    Here is example code fom my bit-banged I2C file:
#define SCL     TRISFbits.TRISF5 // I2C clock
#define SDA     TRISFbits.TRISF4 // I2C data
#define SCL_IN  PORTFbits.RF5    //
#define SDA_IN  PORTFbits.RF4    //
#define SCL_OUT LATFbits.LATF5    //
#define SDA_OUT LATFbits.LATF4    //

void i2c_dly(void)
{
    Delay_us(1);
}

/***************************************************************************************
* i2c_tx() sends one byte of data
* Returns the final ACK state from the device
* Used in all transfers of data to the external device.
****************************************************************************************/
char i2c_tx(unsigned char d)
{
    char x;
    static char b;

    SCL = 0;
    for(x=8; x; x--)
    {
        if(d&0x80)
            SDA = 1;
        else
            SDA = 0;
        i2c_dly();
        SCL = 1;
        d <<= 1;
        i2c_dly();
        SCL = 0;
    }
    SDA = 1;
    i2c_dly();
    SCL = 1;
    i2c_dly();
    b = SDA_IN;          // Read ACK bit
    SCL = 0;
    return b;
}
Note that sending 1 or 0 is done by writing to the TRIS register....
 
 

OP的PIC设备对每个端口引脚分别开漏控制，使用它。



      以下为原文

    OP's PIC device has open-drain control for each port pin individually, use it.

1-Wire代码从湿度/温度设备读取：忽略标志，这只是为了返回温度C，F或K.



      以下为原文

    1-wire code to read from a humidity/temperature device:
Ignore the flag, that was just to return temperature in C, F or K.
//----------------------------------------------------
int read_humidity(int *Humidity, int *Temperature, int Flag){
    //pin 11 rb4
    ulong d=25;
    ulong data=0;
    ubyte chk=0;
    int f;

    T3CON=_T3CON_TON_MASK;
    PR3=5600;   // 0.000140 - double '1' bit 0.00070
    d=18;
    TRISBbits.TRISB4=0;
    LATBbits.LATB4=0;
    delay_ms(&d);
    LATBbits.LATB4=1;
    d=40;
    delay_us(&d);
    LATBbits.LATB4=0;
    TRISBbits.TRISB4=1;
    //ack
    TMR3=0; IFS0bits.T3IF=0;
    while(PORTBbits.RB4&&!IFS0bits.T3IF);
    if(IFS0bits.T3IF)return DHT_ACK;
    TMR3=0; IFS0bits.T3IF=0;
    while(!PORTBbits.RB4&&!IFS0bits.T3IF);
    if(IFS0bits.T3IF)return DHT_ACK;
    TMR3=0; IFS0bits.T3IF=0;
    while(PORTBbits.RB4&&!IFS0bits.T3IF);
    if(IFS0bits.T3IF)return DHT_ACK;
    IFS0bits.T3IF=0;
    for(f=0;f<40;f++){
        TMR3=0; IFS0bits.T3IF=0;
        while(!PORTBbits.RB4&&!IFS0bits.T3IF);
        if(IFS0bits.T3IF)break;
        TMR3=0; IFS0bits.T3IF=0;
        while(PORTBbits.RB4&&!IFS0bits.T3IF);
        if(IFS0bits.T3IF)break;
        if(f>31){chk<<=1;chk|=(TMR3>2000);}
        else {data<<=1;data|=(TMR3>2000);}
    }
    if(f<40)return DHT_TO;
    ubyte *da=(ubyte *)&data;
    if(chk!=(da[0]+da[1]+da[2]+da[3]))return DHT_CHK;
    *Humidity=da[3];
    *Temperature=da[1];
    return DHT_OK;
}
//----------------------------------------------------

该传感器似乎是一个AOSUN AM2302。它的通信设计相当简单：1）通过将数据线拉低到25 MS2来给出读命令，期望40位编码为脉冲宽度的数据（每个数据字节用于温度和湿度，然后是一个检查字节）3）EEPROM器件具有更复杂的特性。COMM结构，您需要向设备发送命令，然后还需要数据（如果写入）或从设备读取数据（如果读取）。我的代码片段来自这样的EEPROM接口，它只使用2线I2C接口，因此也有一个时钟线来行使。



      以下为原文

    That sensor seems to be an Aosong AM2302.
It is rather simple in its design of communication:
1) Give read command by pulling data line low for 25 ms
2) expect 40 bits of data encoded as pulse widths (2 data bytes each for temp and humidity, then a check byte)
3) Done
 
An EEPROM device has a more complex comm structure where you need to send commands to the device and then also data (if writing) or read data from the device (if reading).
My code snippet was from just such an EEPROM interface only it uses a 2-wire I2C interface so there is also a clock line to exercise.

我使用I2C或SPI EEPROM。它是我仅有的1线代码，但是它显示了TrISX的使用。



      以下为原文

    I use i2c or spi eeproms.
 
It's the only 1-wire code I have but it shows the use of TRISx.

杰瑞-谢谢你抓住了。我也根据Gort的例子把它改成了下面的例子。我现在刚开始我的前8个字节的0x00。我的时间有点长（76US，而不是70US），所以我调整了没有用。我对如何使用开式排水管感到困惑。现在，我将端口D1的ODC寄存器设置为1，并将其放在那里，但是数据表将其称为“开漏输出”，所以当我将PIN更改为输入时，是否应该将ODC寄存器中的位设置为0？我试着将它设置在Read ToWo函数中，然后我的代码甚至不读存在脉冲。char Read Type（空隙）{char Read yDATA＝0；OWAWORKEDION PIN＝低；//LATD＝0 OWApPixOnDead＝输入；//TrIS＝1（OWAdRead 1＝1）Read数据＝SET；否则Read OxDATA＝CLISH；Read Read DATA；}仍然。



      以下为原文

    Jerry - thanks for catching that.  I changed it to the following based on Gort's example too.  I am now just getting 0x00 for my first 8 bytes.  My timing was slightly long (76us instead of 70us), so i adjusted that to no avail.  I am confused about how to use the open drain configuration.  Right now I am setting the ODC register for port D1 to a 1 and just leaving it there, but the data sheet calls it 'open drain output', so when i change the pin to an input, should I set the bit in the ODC register to a 0?  I tried setting it to - in the read_OW function and then my code wouldn't even read the presence pulse.
 
char read_OW (void)
{
char read_data=0;

OW_WRITE_PIN = LOW; //LATD = 0
OW_PIN_DIRECTION = INPUT; //TRIS = 1
if (OW_READ_PIN == 1)
read_data = SET;
else
read_data = CLEAR;

return read_data;
}
 
Still 

如果您使用的是EEPROM上拉电阻，那么不要在PIC上设置开漏。我使用的电阻是4.7KOK在使用UPLC的开路漏极I2C规格。有时您会再次读取数据表直到它下沉。



      以下为原文

    If you are using a pull-up resistor from the eeprom then do not set the open drain on the pic.
 
Resistors I've used were 4.7K
 
Look at open drain i2c specs that use pull-ups.
 
Sometimes you have the read the datasheets again until it sinks in.

为什么？”排水口！=“弱拉起”



      以下为原文

   
Why?
"open drain" != "weak pullup"
 

Gort是对的——我去掉了开漏设置，在端口引脚方向的改变和读写端口之间放入了一个nop-（），现在我得到了预期的结果。



      以下为原文

    Gort was right - i got rid of the open drain settings and put in a Nop() in between the port pin direction change and reading or writing to the port and now i am getting the expected result.

简化：同样，DS28 EC20数据表表示它需要任何速度的2.2 Kohm max的上拉电阻。



      以下为原文

   
Simplified:
char read_OW (void)
{
    OW_PIN_DIRECTION = INPUT; //TRIS = 1
    Nop();
    return OW_READ_PIN;
}

Also, the DS28EC20 datasheet states it requires a pullup resistor of 2.2 Kohm max at any speed.
 
 

因为它的工作，我会留下足够好的单独，但…不使用引脚在OD模式只是设置在ODC寄存器中的一次在启动/初始化。然后，对于输出，您可以只写入LATD1位（写0 =低输出，写1 = OD’高输出）。因为ODC＝1，当LAT是高的PIN浮动和被外部上拉电阻拉高。在这种状态下，外部设备可以将引脚拉低。当您想要读取引脚的状态时，确保LAT位设置为1，并读取端口寄存器。如果你已经设置了LAT＝0，那么引脚也将是低的，外部设备将无法驱动它高。



      以下为原文

    Since it's working I'd leave well enough alone, but...

No.

To use the pin in OD mode just set the bit in the ODC register once at startup/init.

After that, for output you can just write to the LATD1 bit (write 0=low output, write 1=OD 'high' output).
Since ODC=1, when the LAT is high the pin floats and is pulled high by the external pullup resistor. In this state the external device can pull the pin low.

When you want to read the state of the pin make sure the LAT bit is set=1 and read the PORT register. If you've set the LAT=0 then the pin will be low too and the external device won't be able to drive it high.

…或设置TIS位输入，它应该断开输出驱动器。



      以下为原文

   
... or set the TRIS bit to input and it should disconnect the output driver.