Raspberry pi Blynk value display in Python (API)

Need Help With My Project
1

Hello friends. I am doing a simple Blynk project and I seem to have approached a problem which I cannot solve. I am using a raspberry pi, and so far I have managed to create a code which can take input from buttons and sliders. But now I want to be able to do the exact same thing, but this time, get data from the Pi to Blynk. I want to display text on “value display”. But i dont seem to find a solution with regards to python.

For button, I would just do:

led = Blynk(auth_token, pin = “V3”)

Please help me with regards to how can I do the same way and get text from Pi to the Value display. For example, I want to display “0.1” on value display. How to do this? Any help would be appreciated, because all the things I have searched about this cater more towards Arduino users, not raspberry pi users.

2

Arduino and ESP are the most commonly used devices with Blynk in this forum.

But I am also slowly teaching myself to use the RPI (as Blynk client) with the NodeJS (Javascript) and Python languages.

I find it best to look through the examples on the GitHub page for each applicable language… for example the Python page…

Check out the 02_virtual_read.py and 03_virtual_write.py examples… well check them all out :stuck_out_tongue:

There is a lot of looking at how things were done and then Googling Python commands and experimenting…

Note: The syntax and letter case for Blynk commands is different then Arduino code… for example NO capitalization of blynk or use of the V in a vPin numbering…

For example, I think this should do what you are asking … at least in the most basic of ways…

blynk.virtual_write(3,'0.1') # Send the value 0.1 to a display widget on V3
3

Well, I tried the one you suggested, but sadly it didnt work. Basically let me explain how I did it.

I did:
led = Blynk(token,pin = “V3”)
ledStatus = led.get_val()

now basically, V3 is a button on Blynk. If I push it, ledStatus becomes 1 and obviously if not, it becomes 0.

When I tried to check the functions associated with this object, I found something called

set_val(self, value,request)

which I figure is the equivalent of the get_val() function. I understand that value would be the text I want to put (ie. “0.1”). But do you know what does the request mean? Like what do you think I should type there?

4

Where are you getting these commands from?? Where is the rest of your code?

5 
import spidev
from blynkapi import Blynk
import time
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(8, GPIO.OUT)
GPIO.output(8,GPIO.LOW)
auth_token = "fc11c09f1xxxxxxxxxxbe52ee70548"
spi = spidev.SpiDev()
spi.open(0, 0)
spi.max_speed_hz = 976000
mcp = Blynk(auth_token, pin = "V1")
display = Blynk(auth_token, pin = "V2")
led = Blynk(auth_token, pin = "V3")

def write_pot(input):
    msb = input >> 8
    lsb = input & 0xFF
    spi.xfer([msb, lsb])


	
while True:
    blink = led.get_val()
    
    if blink[0] == u'1':
	print("inside if statement")
        GPIO.output(8,GPIO.HIGH)
        mcpval =  mcp.get_val()
        mcpval[0] =int(mcpval[0])
        write_pot(mcpval[0])
	#display.virtual_write(2,'0.1')
	print(Blynk.set_val_old.func_code.co_varnames)
	
	break
	
    else:
	GPIO.output(8,GPIO.LOW)

so basically this is the code of my project. These are python commands from the Blynk library. Basically I have a button which i push, and a slider to control its brightness. But now I want to be able to display text on my blynk app. Like when I push the button, it displays a particular text on the value display area. Please help me if you can.

6

I had to properly format your posted code as required in the Welcome Topic…

Blynk%20-%20FTFC

I also blanked out part of your AUTH code so that others will not try to control your stuff :stuck_out_tongue:

I don’t quite understand what you are doing here… but it doesn’t look correct :face_with_monocle:

Start off with a simple sketch like this (Blynk Button, LED & Display Widgets) and confirm it works, then start adding all your other stuff one piece at a time…

import BlynkLib

BLYNK_AUTH ='xxxxxxxxxx'

# Initialize Blynk
blynk = BlynkLib.Blynk(BLYNK_AUTH)

@blynk.VIRTUAL_WRITE(0) # Virtual Button/Switch on V0
def my_write_handler(value):
    if int(value) == 1:
        blynk.virtual_write(1,255) # Turn ON Virtual LED on V1
        blynk.virtual_write(2,'LED is ON') # Send Text to Display on V2
    else:
        blynk.virtual_write(1,0) # Surn OFF Virtual LED on V1
        blynk.virtual_write(2,'LED is OFF') # Send Text to Display on V2


# Start Blynk (this call should never return)
blynk.run()
7

Hmmm… I think you are using Blynk differently then the “official” Blynk Python Library method… I am installing and using the Blynk Python Library as shown on the developers GitHub page… You seem to be using some API method??

8

Yes I am using a blynk api for this. It is different from the code which you suggested. And so far, I have got the button and slider working perfectly with the code I showed. Its only when I want to display on the value display area I am having trouble.

9

Sorry, but I am totally unfamiliar of that API method for Python.

I can use normal Blynk API commands to control, or get feedback from, the normal Python Library so didn’t even know there was a way like however you are doing it.