Dave,

I would be interested to see how you would implement the binary/BCD conversion. The code I posted is my take on the shift and add 3/double dabble routine.

The original data will come from 4 74HC165 shift registers, I will shift in 4 bytes of data and store these as BBIN1...4. The program is part of a frequency counter I am working on. I am 4 using 74HC393 binary counters followed by the shift registers to give a 32 bit count. The PIC will only do the arithmetic and control the MAX7219 display driver. I will be using an external timebase.

I'm sure this isn't the simplest or most elegant way to implement a frequency counter, but I will learn more doing it this way. My first thought is that I may be able to reduce the number of 393/165 chips and count the number of overflows during the timing period to reduce chip count.

I could use 74HC390 to avoid having to do the binary/BCD conversion but this would need more chips due to the redundancy of bits in BCD

Regards,
John