For my project I have to connect a IMU sensor via SPI with a Cortex M4 microcontroller (Teensy 3.6). The sensor has to be about 0.5m apart so I will probably have to add some extras to deal with the longer than normal wires.
Ideally I would like to calculate/simulate my bus before soldering everything. I made a LTSpice model to simulate the behaviour of a 1MHz square wave (see bellow). What I'm not sure is if I have modeled the input of uC and Sensor correctly (as it is now the uC would just float high). From the datasheets I could only gather that the uC has a capacitance of 7pF on it's digital pins and the IMU (MPU9250) 10pF. So I added two capacitors as shown in the schematic bellow. Additionally the IMU breakout board has a 10k pull up. What I could not find is if there is a second internally pull-up that I'm missing.
I want to use the simulation to get a sense to where I can adjust my components to stay within rise time margins and avoid transmission line effects by adding a low-pass filter if necessary.
I'd appreciate any feedback on this.