Any examples of rpigpior with Shiny?

[dcaud]

I'm wondering whether Pi's GPIO would work well with R's Shiny.

1. Could you continuously monitor an input from a GPIO and continuously plot it within Shiny? Perhaps something like:

library(shiny)
library(rpigpior)
library(ggplot2)

# Initialize GPIO
rpigpior::setup(pin = 2, mode = "in")

ui <- fluidPage(
  titlePanel("Real-Time GPIO Pin Monitoring"),
  mainPanel(
    plotOutput("pinPlot")
  )
)

server <- function(input, output, session) {
  
  # Function to read pin status
  readPin <- reactivePoll(1000, session,
                          checkFunc = function() {
                            Sys.time()  # Forces reactive to execute every 1 second
                          },
                          valueFunc = function() {
                            rpigpior::read_pin(pin = 2)
                          })
  
  # Generate plot for output
  output$pinPlot <- renderPlot({
    data <- data.frame(
      Time = Sys.time(),
      Value = readPin()
    )
    
    ggplot(data, aes(x = Time, y = Value)) +
      geom_line() +
      labs(title = "GPIO Pin 2 Status", x = "Time", y = "Value") +
      ylim(0, 1)  # Since GPIO pin values are either 0 or 1
  })
}

# Run the application
shinyApp(ui = ui, server = server)

Also, I wonder how this could be adapted to monitor a momentary switch -- something with short pulse that would not span the polling duration set in the Shiny app.

If anyone has examples (or can just say that this generally would work) would be super helpful.

[mnr]

This all seems to be possible. It implies you are running shiny on a raspberry pi - or passing data from the raspberry pi to an external data cache.

There is a pretty complete write-up on running shiny on RPi here... . I suspect there are easier ways to do this - certainly start with r4pi

[mnr]

regarding monitoring a switch, I haven't implemented generating an interrupt for a switch - so currently that would done by polling the button every so often. Again - ought to work, but I'm not sure how shiny timing would feel about polling.

When you suggest a momentary switch, are you referring to a manual pushbutton? Or are you watching for a signal from some other device?

[dcaud]

Great! Thanks for the general confirmation that this seems possible.

I was thinking of a manual pushbutton as I was trying to see the limits of the polling. I presume some kind of proper interrupt would lessen the problems associated with trying to poll events that are short-lived.

In general, I was wondering the feasibility of having Shiny be the front-end (and more!) for a number of possible Pi applications -- including monitoring multiple kinds of inputs and controlling multiple kinds of outputs (PWM, etc.).