SWD_RAW_RECEIVE

The SWD_RAW_RECEIVE function receives raw data on the SWD pins. Receiving data via this function bypasses XJTAG's handling of the bidirectional nature of the protocol, and will clock in the next bitLength bits irrespective of the state of the interface.

If SWD pins are shared with JTAG TAP pins, the first JTAG access after using SWD_RAW_RECEIVE will reset the JTAG chain.

SWD_RAW_RECEIVE( INT bitLength )

Example

  INT data, ack, idcode, parityBit, parityError;

  SWD // Places the target into SWD mode
    
    // Using raw functions to manually use the bidirectional protocol
    
    SWD_RAW_SEND(8, 0b10100101);      // Request id code. [0]start=0b1, [1]debug port=0b0, [2]read=0b1,
                                      // [3..4]address=0b00, [5]parity=0b1, [6]stop=0b0, [7]park=0b1.

    SWD_RAW_RECEIVE(4)(data);  // Receive the acknowledgement. [0]turnaround bit, [1]OK, [2]wait, [3]fault.
    ack := data[3..1];
    PRINT("Acknowledgement: ", FORMAT(ack, "%#03b\n"));
    IF ack != 0b001 THEN EXIT; END;  // Check it returned the OK response.
    
    SWD_RAW_RECEIVE(33)(data); // Receive the data [0..31]data, [32]parity.
    idcode := data[31..0];
    parityBit := data[32];
    PRINT("IDCODE: ", FORMAT(data, "%#08x\n"));
    PRINT("Parity Bit: ", parityBit, "\n\n");
  END;

  SWD
    
    // The same thing achieved using the built-in protocol functions
    
    SWD_EXIT_ON_ERROR(FALSE);
    SWD_READ(0, 0)(idcode, ack, parityError);        // Debug port, address 0.
    PRINT("IDCODE: ", FORMAT(data, "%#08x\n"));
    PRINT("Acknowledgement: ", FORMAT(ack, "%#03b\n"));
    PRINT("Parity Error: ", parityError, "\n");
  END;

Acknowledgement: 0b001
IDCODE: 0x2ba01477
Parity Bit: 0

IDCODE: 0x2ba01477
Acknowledgement: 0b001
Parity Error: 0