I want to make one counter card, which will give interface to 2 quadrature encoder i.e. 2 channel card with some digital input & outputs.
I am having 3 to 4 options for decoding quadrature input
1) Using HP 2020 IC (16 BIT INBUILT COUNTER)
2) OR LS 7084 + 16 BIT COUNTER
3) OR TI DSP processor which has this port
4) OR use CPLD

Finally I am thinking of using CPLD as I found other options are costly.
I want to ask
a) What maximum frequency that I can give with the combination of CPLD+89c52 for two channels
b) If I am using the 89c52 timers for other work and I use external counters from CPLD how much it will affect the max. Frequency.
c) can u suggest any better solution ?which should not be costly.


regards
vikrant