Bidirectional Port Using DLL in QSPICE?

QSPICE
1

Hi everyone,

I’m currently working with QSPICE and using a DLL block for custom modeling. I noticed that the DLL symbol only allows input and output ports, but there doesn’t seem to be any option for a true bidirectional (inout) port.

In my application, I need a node that:

  • Can be driven by the DLL under certain conditions
  • Can be released (high-impedance) at other times
  • Can always be sensed/read by the DLL

Essentially, I’m trying to emulate something similar to a tri-state or open-drain bidirectional signal.

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2

How about using 1 in and 1 out (then connect this pin to an NMOS) to emulate such open drain pin. Then somehow write a driver in C to perform such function.

Anyway, there is a complication to make it natively. Basically because Qspice Cblock has 1 timestep delay between the input and output and also with how Qspice integrate Cblock with the rest of the analog solver

3

Hi, Mike.

There’s no way to have a bi-directional DLL pin. I had to solve this with a GPIO symbol for my QMdbSim micro-controller simulation project. You can find it here: GitHub - robdunn4/QSpice: QSpice tools, components, symbols, code, etc..

–robert

4

check the I2S example SDA should be bidirectional.
Also like @physicboy said you can have a low impedance output and a high impedance input wired together.
As for the time step delay: just use a smaller step and add some more margin like real systems.
IRL nothing is exact so try triggering on signal edges.