Scroll pHAT HD Scrolling Issues


#1

Hello there,

I am trying to create a simple dice roller for my Scroll pHAT HD. I have written the following (below) in Python, it works in terminal with no problems… but when I try to display it on my Scroll pHAT HD it will not scroll the text for some reason. It just shows the first part of the “You Rolled A…” string. Furthermore all subsequent sentences just appear on top of the old one… I imagine this is something to do with the clear function.

If anyone can point me in the right direction I would be very grateful.

import random
import signal
import time
import scrollphathd as sphd

def roll(sides=6):
num_rolled = random.randint(1,sides)
return num_rolled

def main():
sides = 6
rolling = True
while rolling:
roll_again = raw_input("Ready to roll? ENTER=Roll.Q=Quit. ")
if roll_again.lower() !=“q”:
num_rolled = roll(sides)
sphd.write_string(“You rolled a”, num_rolled)
sphd.show()
sphd.scroll(1)
time.sleep(0.05)

else:
	rolling = False

	print ("You We're On A Roll!")

main()


#2

You should use three backticks to format your code for readability, like so:

```
# Code goes here
```

The scroll() command only moves the buffer as far as you tell it. It needs to be called continuously to keep scrolling.

A continuous blocking* scrolling function might look like this:

import scrollphathd

def scroll_message(message):
    scrollphathd.clear() # Clear the display and reset scrolling to (0, 0)
    length = scrollphathd.write_string(message) # Write out your message
    scrollphathd.show() # Show the result
    time.sleep(0.5) # Initial delay before scrolling
    
    # Now for the scrolling loop...
    while length > 0:
        scrollphathd.scroll(1) # Scroll the buffer one place to the left
        scrollphathd.show() # Show the result
        length -= 1
        time.sleep(0.02) # Delay for each scrolling step

scroll_message("Hello World! How are you today?")

*blocking means your code wont be able to do anything else until the message has finished scrolling


#3

Okay. My first try had a small bug (forgetting import time notwithstanding) so I’ve fixed up this code and added it as an example: https://github.com/pimoroni/scroll-phat-hd/blob/master/examples/simple-scrolling.py

#!/usr/bin/env python

import time

import scrollphathd

print("""
Scroll pHAT HD: Simple Scrolling
A simple example showing a basic scrolling loop for scrolling
single messages across the display.
Press Ctrl+C to exit.
""")


def scroll_message(message):
    scrollphathd.clear() # Clear the display and reset scrolling to (0, 0)
    length = scrollphathd.write_string(message) # Write out your message
    scrollphathd.show() # Show the result
    time.sleep(0.5) # Initial delay before scrolling

    length -= scrollphathd.width
    
    # Now for the scrolling loop...
    while length > 0:
        scrollphathd.scroll(1) # Scroll the buffer one place to the left
        scrollphathd.show() # Show the result
        length -= 1
        time.sleep(0.02) # Delay for each scrolling step

    time.sleep(0.5) # Delay at the end of scrolling

scroll_message("Hello World! How are you today?")

#4

Many thanks Phil, I have tried to integrate your suggestions but still facing similar (if different) troubles. Now Python is upset that “length” is “not defined”… which I feel like it is on [Line 12].

import random
import signal
import time
import scrollphathd

def roll(sides=6):
    num_rolled = random.randint(1,sides)
    return num_rolled

def scroll_message(message, num_rolled):
    scrollphathd.clear() # Clear the display and reset scrolling to (0, 0)
    length = scrollphathd.write_string() # Write out your message
    scrollphathd.show() # Show the result
    time.sleep(0.5) # Initial delay before scrolling

    length -= scrollphathd.width

def main():
	sides = 6
	rolling = True

	while rolling:
		roll_again = raw_input("Ready to roll? ENTER=Roll.Q=Quit. ")

if length > 0:
    scrollphathd.scroll(1) # Scroll the buffer one place to the left
    scrollphathd.show() # Show the result
    length -= 1
    time.sleep(0.02) # Delay for each scrolling step

    time.sleep(0.5) # Delay at the end of scrolling

if roll_again.lower() !="q":
	num_rolled = roll(sides)
	scroll_message("You rolled a", num_rolled)

else:
	rolling = False

print ("You We're On A Roll!")

main()