Two 28X2's monitoring the same pushbuttons?

[vectorspace]

I am adding control pushbuttons to an existing project which has two 28X2's, each running the same code. Each 28X2 monitors serial data from a videoconferencing codec and sends serial commands to an audio/video/XVGA recoder to capture/stream everything whenever a call is received on the codec. There are two codecs and two recorders and they both operate the same way, one codec/recorder pair on each PICAXE. They share the power supply.

Each pushbutton is to be used to tell the corresponding 28X2 to disable or enable monitoring the serial data -- switching from 'monitoring' to 'not monitoring' to 'monitoring' etc. each time the button is pushed.

But, I want to be able to reset both 28X2's by holding both pushbuttons for a couple seconds. I have code that works fine in simulation but I want to be sure that I'm connecting the buttons in a way that will be reliable and will not cause problems of which I am ignorant. The code recognizes that the appropriate button has been pressed and then after a short delay, checks to see if the other button is also pressed. If it is, it SW resets.

Below is a schematic of the pertinent components. The placement and values are purely guesses on my part. Does the circuit look reasonable?

Happy New Year!

 

[nick12ab]

I can see no reason why that won't work.

Don't forget to put pull-up resistors on the actual reset pins of the PICAXEs. Since the switches are on port B, you can also eliminate the need for those external pullups on the switches by using the pullup command.

 

[PaulRB]

Looks ok to me. Maybe 10K rather than 100K.

Paul

 

[mrburnette]

Looks ok to me. Maybe 10K rather than 100K.

Paul

Pull-Up and Pull-Down resistors are commonly selected by experience and/or "rule-of-thumb"
PullUp PullDown

Decide whether your application requires a pull-up, pull-down or both.
For sensor and switch applications it is common practice to use two wires to the sensor, one of them being ground. A pull-up is required in this case , i.e. a resistor connected to a positive power rail, e.g. 5V.

For resistive sensor inputs pick a value comparable to the maximum value the variable resistor will have. Be careful of values less than 1kohm as the sensor may heat up. Values greater than 500Kohm may require slow acquisition times of the ADC.

For switch inputs and many resistive sensors 10K-20K is a very common range of values.