I'm interfacing the encoder output w. QEI pins. I wonder how much is the input impendance of these pins on chip... Could someone let me know?
Thx alot!
Thx but I have tried this way and nothing is found...
What I need is the input impedance of QEI pins but what given is for "A/D" or "D/A" pins... Faint...
with QEI the pins are digitial (make sure you set the pins to be digital) - does TABLE 31-9: DC CHARACTERISTICS: I/O PIN INPUT SPECIFICATIONS which gives the leakage current help?
are you having problems connecting your device?
Let me put it specifically: My encoder signal is 0 - 5VDC pulses, as u know, and I just use a voltage divider (400Ohm & 600Ohm) to shift it down to 0 -3VDC. I havn't tried this yet, but I'm concerning about the impedance issue. That is, is my impedance of "encoder + voltage divider" much smaller than that of DSP QEI pins?
with QEI the pins are digitial (make sure you set the pins to be digital) - does TABLE 31-9: DC CHARACTERISTICS: I/O PIN INPUT SPECIFICATIONS which gives the leakage current help?
are you having problems connecting your device?
You should not have a problem with those sort of values.
In automotive it is common practice to put a 33K series resistor, mounted close to the pin, on digital input pins that go to the outside world.
This is for ESD protection, as during transient testing, the connections are zapped with up to 8Kv positive and negative spikes.