[SOLVED] What GPIO pin is connected to GrovePi's A0 analog input

grovepi
faq

#1

Which pins of raspberry pi is connected to analog input A0?


#2

I am assuming your talking about the GrovePi. I took a peek at the GrovePi+ schematics and as I would suspect he A0 port isn’t directly connected to the Raspberry Pi. The reason is this: the raspberry pi has no analog inputs. That is partly why the GrovePi exists. It can take in analog data and send it off to the pi as Digital. This is the same for all GrovePi versions.

Does that answer your question?

@Matt or someone else, if I am wrong please fix it.


#3

Hi @saishruthi10,


I think the following post is going to help you understand how the GrovePi works:


The reason for which the GrovePi appeared was that the Raspberry Pi didn’t have the functionalities of an Arduino-like system and vice-versa.

Before having the GrovePi, the user didn’t have that many options for connecting an analog sensor or a relay to a Raspberry Pi - it would have required the user lots of time for creating a workaround.

The Raspberry Pi doesn’t have any analog ports, but the GrovePi has.
So through the GrovePi, the Raspberry Pi is able to communicate with those sensors.

You can think of us the ones that created a bridge between the world of computing and the world of sensors / actuators. - I think this is a fun way of thinking of our products.


Also, thank you @graykevinb for making it more clear.
You are entirely correct and there’s nothing wrong in your answer.


Thank you!


#4

Thank you so much for clear responses. I got the working of grove pi.

So the communication between grove pi and pi 3 ( my case) happens only through i2c.

I would like to know, say I have two sensors connected to A0 and A1 port of grove pi. I want to send this sensor data to cloud. I need to give sensor pin details through which I am getting sensor values, to send value to cloud.

So now how can this be done? How values from both sensors will be sent from grove pi to pi simultaneously ?

Please pardon me for any wrong understanding. I am new to grove pi use.


#5

I take it from reading this page that if you plugged something in A0 it is pin 0, A1 is pin 1, and so forth. I haven’t actually used one, but that is how I think it works.


#6

Hi @saishruthi10,

What you need to do is really straightforward:

  1. Stack the GrovePi onto your Raspberry Pi.

  2. Connect a sensor to an analog port - for instance a light sensor to it.

  3. Boot the Raspberry Pi with a Raspbian For Robots image.

  4. Run a Python script which reads the value of the given analog port - let’s say in our case the analog port is A0.

Here’s a mock-up code of what you could have:

import grovepi
from time import sleep

# indicates to A0 port on the grovepi
sensor_pin = 0

# set the GrovePi port to A0
grovepi.pinMode(sensor_pin, "INPUT")

while True:
    # read the sensor's value
    sensor_value = grovepi.analogRead(sensor_pin)

    '''
    code for uploading the sensor data
    to the cloud
    '''

    # wait some time before moving on to the next reading
    sleep(0.5)


The example code I’ve shown you doesn’t have a good architecture, but it proves the point.
Your code should be fault-tolerant and it should be easy to understand.

That’s what engineers are targeting - reliability.


Also, here’s a link to our repository’s folder which holds lots of example programs for you:


If you wish to talk more on this subject, please don’t hesitate and tell / ask us anything you want.
We are here for you.

If you consider this thread to have answered to your questions, again, tell us so we can mark it as solved.


Thank you!


#7

Thanks a ton for the response. I followed the same to send data but in my cloud setup, i need to mention the GPIO pins to which sensors are attached in order to read the its value and send data. I initially thought they are GPIO pins of GrovePI 0 is directly connected to pi zero. But, I read few other posts from which I got to know that they are not directly connected but instead through ATMEGA.

How does it map to pi GPIO Pins. Becasue, I need to specifically mention GPIO pin number of pi to which my sensor is connected. Is there a way out ?


#8

Hi @saishruthi10,

The Diagram

For specifying in a Python script to which port a sensor or actuator is connected, you first need to take a look at the following diagram:



Port Description

As you can see, we have multiple types of ports. These are:

  1. Analog Ports - A0, A1, A2 - with these ports you can read the voltage output of sensors.
    In this diagram, these ports are blue-colored.

  2. Digital Ports - D2, D3, D3, D5, etc - with these ports you can read and write digital values of 1 and 0.
    In this diagram, these ports are orange-colored.

  3. PWM Ports - 3, 5, 6, 9 - with these ports you can set an “analog” value on each specific port - google more on the duty cycle / PWM / PPM concept.
    In this diagram, these ports are green-colored.

  4. I2C Ports - which are yellow-colored and have the SDA & SCL acronyms written.

  5. Serial Ports - which are found in the bottom-left corner of the diagram.
    These 2 yellow-colored ports are the Serials.


What we are only interested (at the moment) are the Analog, Digital and PWM ports.
For each of these ports, you only need to specify their port number inside your Python script.

Excluding the Analog ports in this case (which are just input ports) you can also specify whether the port should be an input or an output with the pinMode() function.

It’s just like in the Arduino environment.


Numbering System

When specifying the pin number for any of these 3 kinds of ports, you can either choose:

  • The orange colored numbering that you can see in the diagram - like 0, 1, 2,…,16, 17.

  • The grey colored numbering that you can see in the diagram - like 0, 1, … 8.

Personally, I prefer the orange notation as it’s more precise and you have more control over the pin you’re using. This numbering system is also useful when you’re working with custom-made sensors.

On the other hand, the grey numbering system is way more easy to use and understand, so for starters, I’d go with this one.


Examples

Please, head over to our repository (link) and take a look at the example programs (link) we have and try them out.
They are really helpful for your understanding of how the GrovePi works.


Hope I’ve offered the right path for understanding the GrovePi platform.

Thank you!


#9

Thanks a lot !! It was very useful in understanding grove pi in depth. I did that finally but writing sensor value to a file and sent it to cloud.


#10

Hi @saishruthi10,

I’m really glad to hear that.
So, I’ll be closing the thread now.

If there’re any other issues, please don’t hesitate to post a question on our forums.

Thank you!


#11