I2CDriverTest03.h

00001 // exchange messages betwen the LPC1768's two i2c ports using low level read/write/start/stop commands
00002 // changing master and slave mode on the fly
00003 
00004 #include "mbed.h"
00005 #include "rtos.h"
00006 #include "I2CMasterRtos.h"
00007 #include "I2CSlaveRtos.h"
00008 
00009 const int freq = 400000;
00010 const int adr = 42<<1;
00011 const int len=34;
00012 const char mstMsg[len]="We are mbed, resistance is futile";
00013 const char slvMsg[len]="Fine with me, let's get addicted ";
00014 
00015 static void slvRxMsg(I2CSlaveRtos& slv)
00016 {
00017     char rxMsg[len];
00018     memset(rxMsg,0,len);
00019     if ( slv.receive() == I2CSlave::WriteAddressed ) {
00020         int cnt=0;
00021         while(cnt<len) rxMsg[cnt++]=slv.read();
00022         slv.stop(); // stop sretching low level of scl
00023         printf("thread %x received message (sz=%d) as i2c slave: '%s'\n",Thread::gettid(),cnt,rxMsg);
00024     } else
00025         printf("Ouch slv rx failure\n");
00026 }
00027 
00028 static void slvTxMsg(I2CSlaveRtos& slv)
00029 {
00030     if ( slv.receive()==I2CSlave::ReadAddressed) {
00031         int cnt=0;
00032         while(cnt<len && slv.write(slvMsg[cnt++]));
00033         slv.stop(); // stop sretching low level of scl
00034     } else
00035         printf("Ouch slv tx failure\n");
00036 }
00037 
00038 static void mstTxMsg(I2CMasterRtos& mst)
00039 {
00040     mst.start();
00041     if(!mst.write(adr & 0xfe))printf("adr+W not acked\n");
00042     int cnt=0;
00043     while(cnt<len && mst.write(mstMsg[cnt++]));
00044     // give the slave a chance to stop stretching scl to low, otherwise we will busy wait for the stop forever
00045     while(!mst.stop())Thread::wait(1);
00046 }
00047 
00048 static void mstRxMsg(I2CMasterRtos& mst)
00049 {
00050     char rxMsg[len];
00051     memset(rxMsg,0,len);
00052     
00053     mst.lock(); // no special reason, just a test
00054     mst.start();
00055     if(!mst.write(adr | 0x01))printf("adr+R not acked\n");
00056     int cnt=0;
00057     while(cnt<len-1) rxMsg[cnt++]=mst.read(1);
00058     mst.unlock();
00059     rxMsg[cnt++]=mst.read(0);
00060     // give the slave a chance to stop stretching scl to low, otherwise we will busy wait for the stop forever
00061     while(!mst.stop())Thread::wait(1);
00062     printf("thread %x received message (sz=%d) as i2c master: '%s'\n",Thread::gettid(),cnt,rxMsg);
00063 }
00064 
00065 static void channel1(void const *args)
00066 {
00067     I2CMasterRtos mst(p9,p10,freq);
00068     I2CSlaveRtos slv(p9,p10,freq,adr);
00069     while(1) {
00070         slvRxMsg(slv);
00071         slvTxMsg(slv);
00072         Thread::wait(100);
00073         mstTxMsg(mst);
00074         Thread::wait(100);
00075         mstRxMsg(mst);
00076     }
00077 }
00078 
00079 void channel2(void const *args)
00080 {
00081     I2CMasterRtos mst(p28,p27,freq);
00082     I2CSlaveRtos slv(p28,p27,freq,adr);
00083     while(1) {
00084         Thread::wait(100);
00085         mstTxMsg(mst);
00086         Thread::wait(100);
00087         mstRxMsg(mst);
00088         slvRxMsg(slv);
00089         slvTxMsg(slv);
00090     }
00091 }
00092 
00093 int doit()
00094 {
00095     Thread selftalk01(channel1,0);
00096     Thread selftalk02(channel2,0);
00097     Thread::wait(5000);
00098     return 0;
00099 }
00100