So, recently I've discovered shift registers, and the applications of these little chips are absolutely stunning... How have I not heard of these before!
Anyway, I'm working on pulling together a robotics project and it requires a large number of servos (at least twelve, two per leg.) and I cannot be bothered to fork out the money to get a control board like the one Adafruit offers, so I was thinking of using shift registers paired up with one of the PWM outputs on the arduino board. Basically, a couple shift registers will be daisy-chained and connected to the board using a serial output, the shift registers outputs will be connected to bases of an array of transistors, the PWM output of the arduino will be connected to the collectors of the transistor array, and the data line for each of the twelve servos will be connected to the emitters of the transistor array.
In essence, I'd be using a shift register to decide which of a set of servo motors the PWM pin is currently attached to.
So, recently I've discovered shift registers, and the applications of these little chips are absolutely stunning... How have I not heard of these before!
Anyway, I'm working on pulling together a robotics project and it requires a large number of servos (at least twelve, two per leg.) and I cannot be bothered to fork out the money to get a control board like the one Adafruit offers, so I was thinking of using shift registers paired up with one of the PWM outputs on the arduino board.
A couple shift registers will be daisy-chained and connected to the board using a serial output, the shift registers outputs will be connected to bases of an array of transistors, the PWM output of the arduino will be connected to all of the collectors of the transistor array, and the data line for each of the twelve servos will be connected to the emitters of the transistor array.
In essence, I'd be using a shift register to decide which of a set of servo motors the PWM pin is attached to, and I can issue commands to that set using the PWM pin. I've already done a very basic test to check that this works in principle, and it seems to, but I have two questions: does a standard servo motor have memory? That is, if I set it to move 80 degrees to a certain spot once and immediately leave it, will it be able to remember to stay there for an extended period of time? Secondly, are there any obvious problems with this set up, as I have described it?