I’ve successfully created an SPI cable to plug in to a .NET Gadgeteer Raptor board (from GHI electronics), and got the Raptor talking over SPI to the Pixycam/CMUcam5. I’ve converted the Arduino code into C# .NET and it ‘works’ to some extent.
However, while I do see data coming from the cam (I cover the lens an I get no data, I uncover it and I get data), I don’t get a start of frame or block marker (AA 55 hex or 170 85 decimal). When I use PixyMon on my PC, I see an object detected and its signature 1. On the Raptor I do get bytes 170 170 (and 85 85 regularly, but NOT 170 85) and here’s an example of the bytes that follows, any ideas why I am not seeing AA 55 hex or 170 85 decimal? If there anything I need to do in the PixyMon configuration, I have created a signature and it identifies the object OK, and have set the output interface type to zero (SPI with no Slave Select)?
170
170
5
48
0
32
39
128
115
0
152
1
84
85
82
80
45
64
0
0
62
1
160
2
224
11
Would any SPI settings (clock, rising edge sampling, clock idle high/low) or any 2s compliment stuff alter/corrupt the data coming in? I am assuming because I’m seeing data coming from the cam that I have the SPI setting right. I have played about with some of the SPI settings…
SPI.Configuration PixyCamSPIConfig = new SPI.Configuration(
Cpu.Pin.GPIO_NONE, //chip select port (was Cpu.Pin.GPIO_Pin1)
false, //chip select active state
0, //chip select setup time
0, //chip select hold time
false, //clock idle state
true, //clock edge
1000, //clock kHz (1mhz)
spiModule //SPI module defined above
);
My code to read data is very similar to Arduino code…
private byte GetByte(byte dataInTheOutQueue)
{
byte[] buffer = new byte[1];
PixyCamSPI.WriteRead(new byte[] { dataInTheOutQueue }, buffer);
Debug.Print("read byte:" + buffer[0]);
return buffer[0];
}
Code to Get start of frame… (never finds the start of frame because it never finds 170 85)…
private const UInt16 PIXY_FRAME_START_WORD = 0xaa55; //2 of these = start of new frame or one of these followed by…
private const UInt16 PIXY_FRAME_START_WORD_CC = 0xaa56; //one of these (cc=colour code object)
private const UInt16 PIXY_START_WORD_WRONG_ORDER = 0x55aa; //need to resync if this is read (one byte out when reading)
private bool GetStartOfFrame()
{
UInt16 w;
UInt16 lastw = 0xffff;
Debug.Print("getting start of frame...");
while (true)
{
w = GetWord();
if (w==0 && lastw==0)
{
Thread.Sleep(1);
return false;
}
else if (w==PIXY_FRAME_START_WORD && lastw==PIXY_FRAME_START_WORD)
{
_IsColourBlock = false;
return true;
}
else if (w==PIXY_FRAME_START_WORD_CC && lastw==PIXY_FRAME_START_WORD)
{
_IsColourBlock = true;
return true;
}
else if (w==PIXY_START_WORD_WRONG_ORDER)
{
GetByte(0); // resync
}
lastw = w;
}
}