Not your situation, just a point to remember, when using 'reset' you start from 0v and not 1/3rd Vcc.
For those interested, what I am trying to do here is to run my UNO based project on a set of AA batteries for 1-2 years (6 Eneloop AA in series).
I suspect I am missing something fundamental here.Any help/hints are welcome!
I working on project where I need to send a pulse to the active low trigger on a 555 timer using an Arduino. I have this pin connected via a 20K pull-up resistor to +5V. if I manually ground this pin for a split second everything works fine in timer part of my circuit. For the Arduino part I was thinking of using a digital pin, assign it as an output, and then set it to low with a digitalWrite() call for a short time and then set it back up to high using another digitalWrite() call. This works fine when I use the Arduino by itself.
The problem I have is when I connect this digital pin to the trigger pin in the timer circuit. For some reason the pulse does not go high (stays around 1V) and I don't understand why. Do I need to use another method? Add more/less pull-up/down resistors?
I should also add that my timer circuit is running all the time and I would like the Arduino to not trigger the timer during Arduino's power-on cycle but only when a certain condition is fulfilled in the Arduino code and then go low for the first time (trigger pulse). I can easily add capacitors to filter out spikes etc. I tried many things but so far no luck and I suspect I am missing something fundamental here.Any help/hints are welcome!
Show us the circuit please, words are a poor substitute... Perhaps you mean pin 2 on the 555, the trigger pin (its not a logic pin, so saying "active low"is meaningless - it goes into a comparator, as does pin 6 the threshold input. pin 2 voltage iscompared to Vcc/3 (one third the 555's supply voltage).
For those of you following this thread, here is a complete schematic of my circuit.