几天来，我一直在努力解决一个问题。我需要你的帮助。
我正在尝试从运行 Windows CE7 的板上连接到 I2C。该板是边界设备Nitrogen6X。
我正在尝试用 C# 编写代码。
经过大量的谷歌搜索和反复试验，我现在可以用 I2C 完成几乎所有的事情（我的意思是我将大多数命令包装在有效的方法中）。当然，我还不能做的一件事是阅读/写作。我一直在尝试一些不同的实现，移植据说可以工作的 C 和 C++ 代码。无济于事。目前我正在将更多的精力放在我将在这里复制的两个实现上。
这些实现都不适合我。两者都进入错误管理部分，并且都报告错误号 87 (ERROR_INVALID_PARAMETER)。
有没有人在这类问题上有经验？有人能指出我做错了什么吗？
编辑 1：我可能应该提到，我试图通过简单地将示波器插入到板上的 I2C3：SDA 和 SCL 引脚上“查看”一些信号。I2C 总线上没有连接实际设备。我希望这会在发送第一个字节（地址+读/写）后给我一些错误，因为不会收到确认位。但是，我在代码中看到了错误 87，并且从示波器看到的信号没有变化（两者都在空闲时保持高电平）。
（代码片段如下）
第一个使用指针和东西，可能更接近 C++ 代码：
StructLayout(LayoutKind.Sequential)]
unsafe public struct UNSAFE_I2C_PACKET
{
//[MarshalAs(UnmanagedType.U1)]
public byte byAddr; //I2C slave device address
//[MarshalAs(UnmanagedType.U1)]
public byte byRw; //Read = I2C_Read or Write = I2C_Write
//[MarshalAs(UnmanagedType.LPArray)]
public byte* pbyBuf; //Message Buffer
//[MarshalAs(UnmanagedType.U2)]
public Int16 wLen; //Message Buffer Length
//[MarshalAs(UnmanagedType.LPStruct)]
public int* lpiResult; //Contain the result of last operation
}
[StructLayout(LayoutKind.Sequential)]
unsafe public struct UNSAFE_I2C_TRANSFER_BLOCK
{
//public I2C_PACKET pI2CPackets;
public UNSAFE_I2C_PACKET* pI2CPackets;
public Int32 iNumPackets;
}
[DllImport("coredll.dll", EntryPoint = "DeviceIoControl", SetLastError = true)]
unsafe internal static extern int DeviceIoControlCE(
IntPtr hDevice, //file handle to driver
uint dwIoControlCode, //a correct call to CTL_CODE
[In, Out]byte* lpInBuffer,
uint nInBufferSize,
byte* lpOutBuffer,
uint nOutBufferSize,
uint* lpBytesReturned,
int* lpOverlapped);
unsafe public void ReadI2C(byte* pBuf, int count)
{
int ret;
int iResult;
UNSAFE_I2C_TRANSFER_BLOCK I2CXferBlock = new UNSAFE_I2C_TRANSFER_BLOCK();
UNSAFE_I2C_PACKET i2cPckt = new UNSAFE_I2C_PACKET();
//fixed (byte* p = pBuf)
{
i2cPckt.pbyBuf = pBuf;// p;
i2cPckt.wLen = (Int16)count;
i2cPckt.byRw = I2C_READ;
i2cPckt.byAddr = BASE;
i2cPckt.lpiResult = &iResult;
I2CXferBlock.iNumPackets = 1;
//fixed (I2C_PACKET* pck = &i2cPckt)
{
I2CXferBlock.pI2CPackets = &i2cPckt; // pck;
//fixed (I2C_TRANSFER_BLOCK* tBlock = &I2CXferBlock)
{
if (DeviceIoControlCE(_i2cFile,
I2C_IOCTL_TRANSFER,
(byte*)&I2CXferBlock,//tBlock,
(uint)sizeof(UNSAFE_I2C_TRANSFER_BLOCK),//Marshal.SizeOf(I2CXferBlock),
null,
0,
null,
null) == 0)
{
int error = GetLastError();
diag("Errore nella TRANSFER");
diag(error.ToString());
}
}
}
}
}
我正在处理的第二个选项是在托管和非托管之间编组：
[StructLayout(LayoutKind.Sequential)]
public struct I2C_PACKET
//public class I2C_PACKET
{
//[MarshalAs(UnmanagedType.U1)]
public Byte byAddr; //I2C slave device address
//[MarshalAs(UnmanagedType.U1)]
public Byte byRw; //Read = I2C_Read or Write = I2C_Write
//[MarshalAs(UnmanagedType.LPArray)]
public IntPtr pbyBuf; //Message Buffer
//[MarshalAs(UnmanagedType.U2)]
public Int16 wLen; //Message Buffer Length
//[MarshalAs(UnmanagedType.LPStruct)]
public IntPtr lpiResult; //Contain the result of last operation
}
[StructLayout(LayoutKind.Sequential)]
public struct I2C_TRANSFER_BLOCK
{
//public I2C_PACKET pI2CPackets;
//[MarshalAs(UnmanagedType.LPArray)]
public IntPtr pI2CPackets;
//[MarshalAs(UnmanagedType.U4)]
public Int32 iNumPackets;
}
[DllImport("coredll.dll", EntryPoint = "DeviceIoControl", SetLastError = true)]
internal static extern int DeviceIoControlCE(
IntPtr hDevice, //file handle to driver
uint dwIoControlCode, //a correct call to CTL_CODE
[In] IntPtr lpInBuffer,
uint nInBufferSize,
[Out] IntPtr lpOutBuffer,
uint nOutBufferSize,
out uint lpBytesReturned,
IntPtr lpOverlapped);
unsafe public void ReadI2C(byte[] buffer)
{
int count = buffer.Length;
I2C_TRANSFER_BLOCK I2CXFerBlock = new I2C_TRANSFER_BLOCK();
I2C_PACKET I2CPckt = new I2C_PACKET();
I2CPckt.byAddr = BASE;
I2CPckt.byRw = I2C_READ;
I2CPckt.wLen = (Int16)count;
I2CPckt.lpiResult = Marshal.AllocHGlobal(sizeof(int));
I2CPckt.pbyBuf = Marshal.AllocHGlobal(count);
//GCHandle packet = GCHandle.Alloc(I2CPckt, GCHandleType.Pinned);
I2CXFerBlock.iNumPackets = 1;
I2CXFerBlock.pI2CPackets = Marshal.AllocHGlobal(Marshal.SizeOf(I2CPckt)); //(Marshal.SizeOf(typeof(I2C_PACKET)));// //(sizeof(I2C_PACKET));//
Marshal.StructureToPtr(I2CPckt, I2CXFerBlock.pI2CPackets, false);
//I2CXFerBlock.pI2CPackets = packet.AddrOfPinnedObject();
//GCHandle xferBlock = GCHandle.Alloc(I2CXFerBlock, GCHandleType.Pinned);
IntPtr xfer = Marshal.AllocHGlobal(Marshal.SizeOf(I2CXFerBlock)); //(sizeof(I2C_TRANSFER_BLOCK)); //
Marshal.StructureToPtr(I2CXFerBlock, xfer, false);
//IntPtr xfer = xferBlock.AddrOfPinnedObject();
uint size = (uint)sizeof(I2C_TRANSFER_BLOCK);//Marshal.SizeOf(I2CXFerBlock);
uint getCnt = 0;
if ((DeviceIoControlCE(_i2cFile,
I2C_IOCTL_TRANSFER,
xfer,
size,
xfer, //IntPtr.Zero,
size, //0,
out getCnt,
IntPtr.Zero)) == 0)
{
int error = GetLastError();
diag("Errore nella TRANSFER.");
diag(error.ToString());
}
else
{
//success
I2CXFerBlock = (I2C_TRANSFER_BLOCK)Marshal.PtrToStructure(xfer, typeof(I2C_TRANSFER_BLOCK));
I2CPckt = (I2C_PACKET)Marshal.PtrToStructure(I2CXFerBlock.pI2CPackets, typeof(I2C_PACKET));
Marshal.Copy(I2CPckt.pbyBuf, buffer, 0, count);
diag("Success in TRANSFER: " + buffer[0].ToString());
}
Marshal.FreeHGlobal(I2CPckt.pbyBuf);
Marshal.FreeHGlobal(I2CXFerBlock.pI2CPackets);
Marshal.FreeHGlobal(xfer);
//packet.Free();
//xferBlock.Free();
}
编辑 2：我拥有的（据称）工作代码（我无法运行）来自我获得的驱动程序，它可能是部分专有的（因此我无法共享）。但是我在网上找到了 I2C 总线的标头，其中包含以下定义：
#define I2C_MACRO_TRANSFER(hDev, pI2CTransferBlock) \
(DeviceIoControl(hDev, I2C_IOCTL_TRANSFER, (PBYTE) pI2CTransferBlock, sizeof(I2C_TRANSFER_BLOCK), NULL, 0, NULL, NULL))
我最初尝试将“null”赋予参数，因为它在这里完成，但我仍然得到相同的错误代码。
编辑 3：来自同一个驱动程序，结构定义：
// I2C Packet
typedef struct
{
BYTE byAddr; // I2C slave device address for this I2C operation
BYTE byRW; // Read = I2C_READ or Write = I2C_WRITE
PBYTE pbyBuf; // Message Buffer
WORD wLen; // Message Buffer Length
LPINT lpiResult; // Contains the result of last operation
} I2C_PACKET, *PI2C_PACKET;
// I2C Transfer Block
typedef struct
{
I2C_PACKET *pI2CPackets;
INT32 iNumPackets;
} I2C_TRANSFER_BLOCK, *PI2C_TRANSFER_BLOCK;
编辑 4：我尝试实现将 a 传递ref给我的结构的版本，正如@ctacke 在他的评论中所建议的那样。我仍然得到同样的错误，所以我想我一定做了与他想象的不同的事情。这是片段：
[StructLayout(LayoutKind.Sequential)]
public struct REF_I2C_PACKET //public class REF_I2C_PACKET //
{
//[MarshalAs(UnmanagedType.U1)]
public Byte byAddr; //I2C slave device address
//[MarshalAs(UnmanagedType.U1)]
public Byte byRw; //Read = I2C_Read or Write = I2C_Write
//[MarshalAs(UnmanagedType.LPArray)]
public IntPtr pbyBuf; //Message Buffer
//[MarshalAs(UnmanagedType.U2)]
public Int16 wLen; //Message Buffer Length
//[MarshalAs(UnmanagedType.LPStruct)]
public IntPtr lpiResult; //Contain the result of last operation
}
[StructLayout(LayoutKind.Sequential)]
public struct REF_I2C_TRANSFER_BLOCK //public class REF_I2C_TRANSFER_BLOCK //
{
//public I2C_PACKET pI2CPackets;
public IntPtr pI2CPackets;
//[MarshalAs(UnmanagedType.U4)]
public Int32 iNumPackets;
//[MarshalAs(UnmanagedType.LPArray)]
//[MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.LPStruct, SizeConst = 2)]
//public REF_I2C_PACKET[] pI2CPackets;
}
[DllImport("coredll.dll", EntryPoint = "DeviceIoControl", SetLastError = true)]
unsafe internal static extern int DeviceIoControlCE(
IntPtr hDevice, //file handle to driver
uint dwIoControlCode, //a correct call to CTL_CODE
//[MarshalAs(UnmanagedType.AsAny)]
//[In] object lpInBuffer, //
ref REF_I2C_TRANSFER_BLOCK lpInBuffer,
uint nInBufferSize,
byte* lpOutBuffer, //ref REF_I2C_TRANSFER_BLOCK lpOutBuffer,
uint nOutBufferSize,
out uint lpBytesReturned, //uint* lpBytesReturned,
int* lpOverlapped);
unsafe public void RefReadI2C(byte[] buffer)
{
int count = buffer.Length;
REF_I2C_TRANSFER_BLOCK I2CXFerBlock = new REF_I2C_TRANSFER_BLOCK();
REF_I2C_PACKET[] I2CPckt = new REF_I2C_PACKET[2];
I2CPckt[0] = new REF_I2C_PACKET();
I2CPckt[1] = new REF_I2C_PACKET();
I2CPckt[0].byAddr = BASE;
I2CPckt[0].byRw = I2C_READ;
I2CPckt[0].wLen = (Int16)count;
I2CPckt[0].lpiResult = Marshal.AllocHGlobal(sizeof(int));
I2CPckt[0].pbyBuf = Marshal.AllocHGlobal(count);
Marshal.Copy(buffer, 0, I2CPckt[0].pbyBuf, count);
I2CPckt[1].byAddr = BASE;
I2CPckt[1].byRw = I2C_READ;
I2CPckt[1].wLen = (Int16)count;
I2CPckt[1].lpiResult = Marshal.AllocHGlobal(sizeof(int));
I2CPckt[1].pbyBuf = Marshal.AllocHGlobal(count);
Marshal.Copy(buffer, 0, I2CPckt[0].pbyBuf, count);
I2CXFerBlock.iNumPackets = 2;
I2CXFerBlock.pI2CPackets = Marshal.AllocHGlobal(Marshal.SizeOf(I2CPckt[0])*I2CPckt.Length);
uint size = (uint)Marshal.SizeOf(I2CXFerBlock); //sizeof(REF_I2C_TRANSFER_BLOCK);//Marshal.SizeOf(I2CXFerBlock);
//size += (uint)(Marshal.SizeOf(I2CPckt[0]) * I2CPckt.Length);
uint getCnt = 0;
if ((DeviceIoControlCE(_i2cFile,
I2C_IOCTL_TRANSFER,
ref I2CXFerBlock,
size,
null, //IntPtr.Zero,
0, //0,
out getCnt,
null)) == 0)
{
int error = GetLastError();
diag("Errore nella TRANSFER.");
diag(error.ToString());
}
else
{
//success
I2CPckt = (REF_I2C_PACKET[])Marshal.PtrToStructure(I2CXFerBlock.pI2CPackets, typeof(REF_I2C_PACKET[]));
Marshal.Copy(I2CPckt[0].pbyBuf, buffer, 0, count);
diag("Success in TRANSFER: " + buffer[0].ToString());
}
Marshal.FreeHGlobal(I2CPckt[0].pbyBuf);
Marshal.FreeHGlobal(I2CPckt[0].lpiResult);
}
编辑5：
我在网上找到（http://em-works.googlecode.com/svn/trunk/WINCE600/PLATFORM/COMMON/SRC/SOC/COMMON_FSL_V2_PDK1_9/I2C/PDK/i2c_io.cpp）以下代码：
BOOL I2C_IOControl(DWORD hOpenContext, DWORD dwCode, PBYTE pBufIn,
DWORD dwLenIn, PBYTE pBufOut, DWORD dwLenOut,
PDWORD pdwActualOut)
{
/*stuff*/
case I2C_IOCTL_TRANSFER:
{
#define MARSHAL 1
#if MARSHAL
DuplicatedBuffer_t Marshalled_pInBuf(pBufIn, dwLenIn, ARG_I_PTR);
pBufIn = reinterpret_cast<PBYTE>( Marshalled_pInBuf.ptr() );
if( (dwLenIn > 0) && (NULL == pBufIn) )
{
return FALSE;
}
#endif
I2C_TRANSFER_BLOCK *pXferBlock = (I2C_TRANSFER_BLOCK *) pBufIn;
if (pXferBlock->iNumPackets<=0)
{
return FALSE;
}
#if MARSHAL
MarshalledBuffer_t Marshalled_pPackets(pXferBlock->pI2CPackets,
pXferBlock->iNumPackets*sizeof(I2C_PACKET),
ARG_I_PTR);
I2C_PACKET *pPackets = reinterpret_cast<I2C_PACKET *>(Marshalled_pPackets.ptr());
if( (NULL == pPackets) )
{
return FALSE;
}
#else
I2C_PACKET *pPackets = pXferBlock->pI2CPackets;
#endif
#if MARSHAL
struct Marshalled_I2C_PACKET
{
MarshalledBuffer_t *pbyBuf;
MarshalledBuffer_t *lpiResult;
} *Marshalled_of_pPackets;
Marshalled_of_pPackets = new Marshalled_I2C_PACKET[pXferBlock->iNumPackets];
if (Marshalled_of_pPackets==0)
{
return FALSE;
}
MarshalledBuffer_t *pMarshalled_ptr;
int i;
// Map pointers for each packet in the array
for (i = 0; i < pXferBlock->iNumPackets; i++)
{
switch( pPackets[i].byRW & I2C_METHOD_MASK )
{
case I2C_RW_WRITE:
pMarshalled_ptr = new MarshalledBuffer_t(
pPackets[i].pbyBuf,
pPackets[i].wLen,
ARG_I_PTR,
FALSE, FALSE);
if (pMarshalled_ptr ==0)
{
bRet = FALSE;
goto cleanupPass1;
}
if (pMarshalled_ptr->ptr()==0)
{
bRet = FALSE;
delete pMarshalled_ptr;
goto cleanupPass1;
}
break;
case I2C_RW_READ:
pMarshalled_ptr = new MarshalledBuffer_t(
pPackets[i].pbyBuf,
pPackets[i].wLen,
ARG_O_PTR, FALSE, FALSE);
if (pMarshalled_ptr ==0)
{
bRet = FALSE;
goto cleanupPass1;
}
if (pMarshalled_ptr->ptr()==0)
{
bRet = FALSE;
delete pMarshalled_ptr;
goto cleanupPass1;
}
break;
default:
{
bRet = FALSE;
goto cleanupPass1;
}
}
pPackets[i].pbyBuf = reinterpret_cast<PBYTE>(pMarshalled_ptr->ptr());
Marshalled_of_pPackets[i].pbyBuf = pMarshalled_ptr;
}
for (i = 0; i < pXferBlock->iNumPackets; i++)
{
pMarshalled_ptr = new MarshalledBuffer_t(
pPackets[i].lpiResult, sizeof(INT),
ARG_O_PDW, FALSE, FALSE);
if (pMarshalled_ptr ==0)
{
bRet = FALSE;
goto cleanupPass2;
}
if (pMarshalled_ptr->ptr()==0)
{
bRet = FALSE;
delete pMarshalled_ptr;
goto cleanupPass2;
}
pPackets[i].lpiResult = reinterpret_cast<LPINT>(pMarshalled_ptr->ptr());
Marshalled_of_pPackets[i].lpiResult = pMarshalled_ptr;
}
#endif
bRet = pI2C->ProcessPackets(pPackets, pXferBlock->iNumPackets);
#if MARSHAL
DEBUGMSG (ZONE_IOCTL|ZONE_FUNCTION, (TEXT("I2C_IOControl:I2C_IOCTL_TRANSFER -\r\n")));
i = pXferBlock->iNumPackets;
cleanupPass2:
for (--i; i>=0; --i)
{
delete Marshalled_of_pPackets[i].lpiResult;
}
i = pXferBlock->iNumPackets;
cleanupPass1:
for (--i; i>=0; --i)
{
delete Marshalled_of_pPackets[i].pbyBuf;
}
delete[] Marshalled_of_pPackets;
#endif
break;
}
/*stuff*/
}
我不能声称理解 100%，但根据 Windows 命名约定（http://msdn.microsoft.com/en-us/library/windows/desktop/aa378932(v=vs.85).aspx）它会看来我应该发送的大小参数是我传输的总字节数，包括所有内容。我试图自己弄清楚这个数字，但到目前为止我还不能。或者，我想可以尝试对必须将它们转换为字节数组的结构做一些事情。只有我猜它需要有一个特定的字节顺序才能让系统理解它。
任何人都可以参与其中吗？