I need to know how to calculate the termination resistors and PCB trace dimensions that will carry a JTAG emulator probe's signals to a processor on a PCB.
The processor is an STMicroelectronics STM32F373VCT6 and the emulator probe is an IAR I-jet. The schematic for these traces is identical to that on page 50 of:
The input impedance of the processor is very high, so I expect near total reflectance. My first guess is to use trace widths that would have a impedance to ground that is one half impedance of the I-Jet's cable, and set the termination resistors equal to that trace impedance. I figure that this way the voltage at the processor input will, upon reflection, double up and be equal to the voltage the emulator sourced, because after the termination resistor the propagated voltage would be half of what was sourced. I do not have total confidence in that guess. How is this done?
I am also concerned about reflection back from the termination resistors. Because the reflection will see an impedance that is the termination resistor plus the characteristic impedance of the emulator cable. So I know I will not be able to totally suppress oscillations.
STM32F373VCT6:
I-jet: