Passive Device Description Files

A passive device description file is used to describe the connections between the pins of a passive device, such as a resistor or link. There must be one CONNECTION LIST per file. The syntax is:

CONNECTION LIST
    [
      CONNECT pinNumber TO pinNumber;
    |
      PULL pinNumber TO pinNumber;
    |
      COUPLE pinNumber TO pinNumber;
    |
      DIFF_TERM pinNumber TO pinNumber;
    |
      BIAS_TERM pinNumber TO pinNumber;
    ]
    { ... }
END;

CONNECT is used to indicate a series link, such as a low-value resistor or a jumper.

PULL indicates a high-value resistor. By combining this with the power and ground nets in the circuit, the connection test will automatically check that these pull resistors are working properly.

COUPLE indicates a series coupling capacitor on an interconnect (i.e. an AC-coupled link). If the coupling capacitor is on a net controlled by a 1149.6-compliant JTAG device then the connection test is able to test that these capacitors are present and working.

DIFF_TERM is used to indicate a differential termination resistor - a resistor which at DC will appear as a short-circuit, but at higher frequencies is used to apply termination to a differential signal. This term is useful if the differential signal is connected to an 1149.6-compliant JTAG device and can therefore be tested at high frequencies. However, DIFF_TERM is not suitable for representing termination to a reference voltage, or for representing single-ended termination resistors.

BIAS_TERM is used to indicate a referenced termination resistor - a resistor between a signal net and a reference voltage, which will at high frequency provide termination for a differential signal, but at low frequencies may result in cross-talk between nets which are terminated to the same reference voltage. This is often useful for termination resistors around DDR memory devices.

Example

// Resistor pack connections
CONNECTION LIST
    CONNECT 1 TO 8;
    CONNECT 2 TO 7;
    CONNECT 3 TO 6;
    CONNECT 4 TO 5;
END;

If you have a resistor pack with a common connection, you just repeat the pin number.

Example

// Pull Resistor pack with common connection
CONNECTION LIST
    PULL 1 TO 10;
    PULL 2 TO 10;
    PULL 3 TO 10;
    PULL 4 TO 10;
    PULL 5 TO 10;
    PULL 6 TO 10;
    PULL 7 TO 10;
    PULL 8 TO 10;
    PULL 9 TO 10;
END;

Passive Device Description files have the extension .pdd.