I'm planning on chaining together 40 x 74HC595 shift registers. The whole chain of 74HC595s will be controlled by a 5 V microcontroller, which will generate the
Each shift register and the microcontroller will have its own PCB, as illustrated in the diagram below:
Because of mechanical constrains, the distance between each shift register will be of about 30 cm (12 in), so the control signals will travel along a distance of aprox. 12 m (40 ft). Besides that, the whole system will be mounted in a very noisy environment (near fluorescent lights, mains wires etc.)
My concern is that the control signals will be very noisy and the shift registers might output the wrong things. I was thinking of:
- Using a buffer IC on each board, to buffer the control signals. Which one would you recommend?
- Using shielded cables between the boards for the signals
- Lowering the
CLOCKfrequency as much as possible. I only need to update the registers' content a few times a day.
Are the above solutions a good thing to do? What else can I do to keep the (potential) noise in the signal wires to a minimum?