Diff: pixySPI.cpp

Revision:

4:478d4d9193a1

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pixySPI.cpp	Mon Aug 23 11:26:37 2021 +0000
@@ -0,0 +1,129 @@
+    
+
+#include "pixySPI.h"
+ 
+pixySPI::pixySPI(PinName mosi, PinName miso, PinName sclk, int nBlocks)
+    :spi(mosi,miso,sclk)
+{
+    spi.format(8,0); //8bits mode 0
+    spi.frequency(100000); //set the frequency in Hz
+    sync=0xAA55; //start word of a frame coming from the pixy
+    //blocks=new Block[nBlocks]; //allocate space for the blocks
+    //numBlocks=nBlocks;
+    numBlocks=NUM_BLOCKS;
+    bestX=CENTER_X;
+    bestY=CENTER_Y;
+}
+ 
+pixySPI::~pixySPI()
+{
+    //delete blocks;
+}
+ 
+ 
+short pixySPI::readTwoBytesLSB()
+{
+    short out;
+    char read[2]= {0,0};
+    read[0]=spi.write(0x00);
+    read[1]=spi.write(0x00);
+    out=(((short)read[0]) << 8) | read[1];
+    return out;
+}
+ 
+ 
+//this doesn't work
+void pixySPI::readNBytes(char* buf, int num)
+{
+    for (int i=0; i<num; i++) {
+        char byte=spi.write(0x00);
+        memcpy(buf+i, &byte, 1);
+    }
+}
+ 
+void pixySPI::capture()
+{
+    memset(blocks, 0, numBlocks*sizeof(Block)); //destroy the old targets
+    //rec_blocks = 0;
+    for (i=0; i<numBlocks; ++i) {
+        // printf("block %d\n", i);
+        Block* out=&blocks[i];
+        out->signature=INVALID_BLOCK;
+        uint16_t checksum=0;
+        //first we need to detect the start of a block. They all start with 0xAA55
+        char frame[2]= {0,0}; //this is a 2 byte running frame of what is being recieved. It's like a first-in-last-out queue
+        //debug->printf("looking for valid signature\n");
+        Timer t;
+        t.start();
+        while (memcmp((char*)&sync, frame, 2)!=0) {
+            frame[0]=frame[1]; //move byte down
+            frame[1]=spi.write(0x00); //get next byte.
+            if (t.read_ms()>5)
+            {
+                t.stop();
+                return;
+            }
+        }
+        //printf("target\n\n");
+        spi.write(0x00);
+        //ok so we got a valid signature
+        //these didn't end up working
+        //readNBytes((char*)(&checksum), 2); //get the checksum
+        //readNBytes((char*)(&out), sizeof(Block)); //get the rest of the data
+        checksum=readTwoBytesLSB();
+        out->signature=readTwoBytesLSB();
+        out->x=readTwoBytesLSB();
+        out->y=readTwoBytesLSB();
+        out->width=readTwoBytesLSB();
+        out->height=readTwoBytesLSB();
+ 
+        if (checksum!=(out->x+out->y+out->signature+out->width+out->height) || checksum==0) {
+            //debug->printf("checksum doesn't add up %d\n", checksum);
+            out->signature=INVALID_BLOCK; //used for invalid signatures
+        }
+        //printf("found block\n");
+        if (blocks[0].signature!=INVALID_BLOCK)
+        {
+            //mutex->lock();
+            bestX=blocks[0].x;
+            bestY=blocks[0].y;
+            //mutex->unlock();
+        }
+    }
+    return;
+}
+ 
+Block* pixySPI::getBlocks()
+{
+    return blocks;
+}
+ 
+int pixySPI::getNumBlocks()
+{
+    return i;
+}
+ 
+int pixySPI::getBestX()
+{
+    if (bestX>640)
+        return 640;
+    else if (bestX<0)
+        return 0;
+    else
+        return bestX;
+}
+ 
+int pixySPI::getBestY()
+{
+    if (bestY>400)
+        return 400;
+    else if (bestY<0)
+        return 0;
+    else
+        return bestY;
+}
+ 
+char pixySPI::getRawData()
+{
+    return spi.write(0x00);
+}
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