// Periodically modify a flag in the global variables of program slot 1.
// The program in slot 1 is a watchdog program that will notice when this "pings" no longer
// arrive and will stop itself and shut down motors and sensors gracefully.
// On the other side, the pinger will monitor if the watchdog is still running (could have
// been stopped manually by the user) and if so, terminates the Basic program also.
private static void runpings()
{
ByteCodeBuffer c = new ByteCodeBuffer();
c.OP(0x3A); // Move32_32
c.CONST(42); // move this value
c.GLOBVAR(0); // to gloval variable 0-3
c.OP(0x7E); // Memory_Write
c.CONST(1); // program slot 1 = user slot
c.CONST(0); // write to global variables
c.CONST(0); // to global variable 0
c.CONST(4); // write 4 bytes
c.GLOBVAR(0); // take the prepared value 42
c.OP(0x0C); // opProgram_Info
c.CONST(0x16); // CMD: GET_STATUS = 0x16
c.CONST(1); // program slot 1 = user slot
c.GLOBVAR(0);
for (; ;)
{
lock (sync)
{
byte[] packet = null;
try
{
packet = con.DirectCommand(c, 4, 0);
}
catch (Exception e)
{
throw e;
}
// detected communication error or watchdog progam is no longer running
if (packet == null || packet.Length <= 0 || packet[0] == 0x40)
{
System.Environment.Exit(1);
}
}
System.Threading.Thread.Sleep(500);
}
}
private static EV3Connection TestConnection(EV3Connection con)
{
try
{
// perform a tiny direct command to check if communication works
ByteCodeBuffer c = new ByteCodeBuffer();
c.OP(0x30); // Move8_8
c.CONST(74);
c.GLOBVAR(0);
byte[] response = con.DirectCommand(c, 1, 0);
if (response == null || response.Length != 1 || response[0] != 74)
{
throw new Exception("Test DirectCommand delivers wrong result");
}
return(con);
}
catch (Exception e)
{
con.Close();
throw e;
}
}