启动I2C传输时，我应该首先设置SSPBUF还是SEN？

我强烈建议不要使用中断来启动。当然，在非中断代码中查询SSPIF标志，但是不要在中断服务例程中执行这一切。您必须熟知如何在中断中实现状态机来完成它。



      以下为原文

    I would strongly recommend NOT using interrupts to start with.
Sure, poll the SSPIF flag in non-interrupt code, but don't try to do this all inside an interrupt service routine.
You have to be well acquainted with how to implement state machines to do it in an interrupt.
 

事实上，我希望我没有给人实际使用ISR的印象，我只是建议使用国旗。



      以下为原文

   


Indeed, I hope I didn't give the impression to actually use the ISR, I was suggesting just using the flag.

我不太清楚这里的问题。难道我不需要检查一下中断标志，看看我什么时候需要写缓冲区吗？这是我的ISR的片段，显示我的意思：



      以下为原文

   
I'm not quite sure what the problem is here. Don't I need to check the interrupt flags to see when I need to write the buffer? Here's a snippet from my ISR to show what I mean:
 if (SSPIE && SSPIF)
    {
        if (needToSendI2C_Address)//start condition just completed
        {
            i2c_write(i2c_address)
            needToSendI2C_Address = FALSE;
        }else
        {
            if (needToSendI2C_Data)
            {
                i2c_write(i2c_data)
                needToSendI2C_Data = FALSE;
            }
        }
        SSPIF = 0; //clear flag
    }

我不太清楚这里的问题。难道我不需要检查一下中断标志，看看我什么时候需要写缓冲区吗？下面是我的ISR中的一个片段来说明我的意思：你通常不想在ISR内部做这些事情，通常你想尽可能少地在ISR中花费时间。你可以知道何时使用中断标志（不是中断本身）或SS来加载缓冲器。当启动传输时，发送启动条件，等待SEN清除（当启动条件结束时清除），然后加载缓冲器。然后，您可以等待BF清除（当缓冲区中的数据已经完成发送时清除）。然后，您将检查ACK状态位，以确定从设备是否确认数据，并且如果您想发送更多字节，则再次加载缓冲区。或者，如果你不想发送更多的数据，发送一个停止条件出来（笔）。



      以下为原文

   
I'm not quite sure what the problem is here. Don't I need to check the interrupt flags to see when I need to write the buffer? Here's a snippet from my ISR to show what I mean:
 if (SSPIE && SSPIF)
    {
        if (needToSendI2C_Address)//start condition just completed
        {
            i2c_write(i2c_address)
            needToSendI2C_Address = FALSE;
        }else
        {
            if (needToSendI2C_Data)
            {
                i2c_write(i2c_data)
                needToSendI2C_Data = FALSE;
            }
        }
        SSPIF = 0; //clear flag
    }




You usually won't want to do these things inside the ISR itself, generally you want to spend as little time inside an ISR as you possibly can.
You can tell when to load the buffer by using either the interrupt flag (not the interrupt itself) or the SSP status flags.
 
I.E.
When starting a transmit, send the start condition, wait for SEN to clear (it clears when the start condition is finished) then load the buffer.  You can then wait for BF to clear (cleared when data in the buffer has finished sending).  You would then check the ACK status bit to determine if the slave device acknowledged the data and load the buffer again if you want to send more bytes.  Or if you don't want to send any more data, send a stop condition out (PEN).

我不太清楚这里的问题。难道我不需要检查一下中断标志，看看我什么时候需要写缓冲区吗？你所做的是实现一个粗糙的状态机，但是你忽略了各种需要的东西。也就是说，你没有检查SLAVE返回的ACK/NACK状态。你不允许有一个以上的数据字节。你不允许从从属设备读取（这会触发相同的数据。在交易结束时，你不会发送一个停止条件。所有这些事情在非中断代码中都更容易调试。注意我说的“开始”。一旦你有了所有的逻辑排序，并了解如何外围工程，当然，处理它在一个中断服务，如果你需要同时做其他事情。如果你不去，就别去打扰了。



      以下为原文

   
I'm not quite sure what the problem is here. Don't I need to check the interrupt flags to see when I need to write the buffer?
What you have done is to implement a crude state machine, but you've left out various required things.
i.e.
You're not checking the ACK/NAK status returned by the slave
You're not allowing for more than one data byte.
You're not allowing for reading from the slave device (which will trigger the same interrupt)
You're not sending a STOP condition at the end of the transaction.
 
All these things are easier to debug in non-interrupt code.
 
Note I said "to start with". Once you have all the logic sorted, and understand how the peripheral works, sure, handle it inside an interrupt service if you need to to doing other things at the same time. Don't bother if you don't.
 

更新：我用一个Switter case语句编写了一个状态机，I2C看起来工作正常。你没有检查SLAVEE返回的ACK/NACK状态。你不允许有一个以上的数据字节。你不允许从从属设备读取（这会触发相同的中断）。在事务结束时不发送停止条件。检查，检查，不检查，检查。



      以下为原文

    Update: I made a state machine with a switch case statement and I2C seems to be working fine.

You're not checking the ACK/NAK status returned by the slave
You're not allowing for more than one data byte.
You're not allowing for reading from the slave device (which will trigger the same interrupt)
You're not sending a STOP condition at the end of the transaction.

Check, check, not checked, check.