EV3 "Hello World!" program

[afanofosc]

The layer number is encoded into the specified output in this manner by combining one of the OUT_* constants (or a variable containing that constant value) with one of the LAYER_* constants using | or +. The firmware opcodes use two separate parameters for layer and port but the API I have designed combines them into one.

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#define OUT_A    0x01 /*!< Output port A */
#define OUT_B    0x02 /*!< Output port B */
#define OUT_C    0x04 /*!< Output port C */
#define OUT_D    0x08 /*!< Output port D */
#define OUT_AB   0x03 /*!< Output ports A and B */
#define OUT_AC   0x05 /*!< Output ports A and C */
#define OUT_AD   0x09 /*!< Output ports A and D */
#define OUT_BC   0x06 /*!< Output ports B and C */
#define OUT_BD   0x0a /*!< Output ports B and D */
#define OUT_CD   0x0c /*!< Output ports C and D */
#define OUT_ABC  0x07 /*!< Output ports A, B, and C */
#define OUT_BCD  0x0e /*!< Output ports B, C, and D */
#define OUT_ABCD 0x0f /*!< Output ports A, B, C, and D */
#define OUT_ALL  0x0f /*!< All output ports (A-D) */

#define OUT_MASK 0x0f /*!< The output port mask */

  // daisy chain constants
#define LAYER_MASTER 0x00 /*!< The master layer */
#define LAYER_SLAVE1 0x10 /*!< The first slave layer */
#define LAYER_SLAVE2 0x20 /*!< The second slave layer */
#define LAYER_SLAVE3 0x40 /*!< The third slave layer */
#define LAYER_MASK   0x70 /*!< The layer mask */

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  DecodeOutputs(&Outputs, &Layer);
  if (Layer == LAYER_MASTER)
  {
    cmd[0] = opOutputStop;
    cmd[1] = Outputs;
    cmd[2] = useBrake;
    return WriteToPWMDevice(cmd, cmdLen) == cmdLen;
  }
  else
  {
    return false;
    // support for daisychaining not yet implemented
  }

John Hansen

[afanofosc]

I do not plan on implementing support for a single call that controls motors on different layers, but I will give it some thought.

John Hansen

[HaWe]

is the restriction to 4 layers made by the ev3 hardware or by software / by your API ?

[HaWe]

is the restriction to 4 layers made by the ev3 hardware or by software / by your API ?

[totokan]

Thank you for the tutorial, it was really helpful in learning everything about low-level EV3 interfacing! If anyone is interested, I wrote a simple, high-level function call to handle getting info from serial sensors, as well as an example program showing its use. It's pretty rough, but it works!

[lvoc]

I like the way you wrapped the code in high level functions. The same could be used for other sensor interafces.

[HaWe]

I agree,

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int ReadSerial(char port, UART *pUart);

is sth like what I have already been proposing

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GetSensor(char port, long SensorType, long & values[])
// or
GetSensor(char port, long & values[]) // (in plain C: the pointer to the array: * values[])