Problem with analog joystick

[riklaunim]

I have a typical analog joystick board: two pins for power, one for button pressed, two for x and y axis potentiometer value. So I set two ADC pins to read value returned from potentiometers and one digital input to read button pressed status:

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class Joystick:
    def __init__(self, x_axis_pin, y_axis_pin, button_pin):
        self.x_axis = pyb.ADC(x_axis_pin)
        self.y_axis = pyb.ADC(y_axis_pin)
        self.button = pyb.Pin(button_pin, pyb.Pin.IN)

    def get_state(self):
        return {
            'x': self.x_axis.read(),
            'y': self.y_axis.read(),
            'button': self.button.value()
        }

The problem is that:
- pressing button doesn't set the pin to high
- ADC changes only for one axis on the joystick and it changes values for x and y:

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# start
{'x': 2855, 'button': 0, 'y': 2851}
>>> j.get_state()
# x axis on one side
{'x': 4095, 'button': 0, 'y': 3140}
>>> j.get_state()
# x axis on another side
{'x': 5, 'button': 0, 'y': 5}

One is on X12 second is on Y12 and button is on X1. The same joystick works with pymcu (5V):

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from time import sleep

import pymcu

BUTTON_DIGITAL_PIN = 1
X_AXIS_ANALOG_PIN = 1
Y_AXIS_ANALOG_PIN = 2

mb = pymcu.mcuModule()
mb.digitalState(BUTTON_DIGITAL_PIN, 'input')
mb.pinHigh(BUTTON_DIGITAL_PIN)

while True:
    print mb.analogRead(X_AXIS_ANALOG_PIN), mb.analogRead(Y_AXIS_ANALOG_PIN)
    if not mb.digitalRead(BUTTON_DIGITAL_PIN):
        print 'button pressed'
    sleep(0.1)

[dhylands]

As far as the push button goes, I think you need a pullup.

The lines:

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mb.digitalState(BUTTON_DIGITAL_PIN, 'input')
mb.pinHigh(BUTTON_DIGITAL_PIN)

are configuring the pin as an input and then enabling the pull-up.

You used:

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self.button = pyb.Pin(button_pin, pyb.Pin.IN)

which enables no pull-up. Changing this to:

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self.button = pyb.Pin(button_pin, pyb.Pin.IN, pull=pyb.Pin.PULL_UP)

will enable the pull-up in micropython.

I wired up the following:

Simple Joystick

JoyStick.png (21.78 KiB) Viewed 9564 times

and ran this code:

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import pyb

x_pin = pyb.Pin('X12')
y_pin = pyb.Pin('Y12')
button_pin = pyb.Pin('X1')

class Joystick:
    def __init__(self, x_axis_pin, y_axis_pin, button_pin):
        self.x_axis = pyb.ADC(x_axis_pin)
        self.y_axis = pyb.ADC(y_axis_pin)
        self.button = pyb.Pin(button_pin, pyb.Pin.IN, pull=pyb.Pin.PULL_UP)

    def get_state(self):
        return {
            'x': self.x_axis.read(),
            'y': self.y_axis.read(),
            'button': self.button.value()
        }

j = Joystick(x_pin, y_pin, button_pin)

while True:
    print(j.get_state())
    pyb.delay(100)

and I can get this output:

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{'x': 4, 'button': 1, 'y': 1}
{'x': 4, 'button': 1, 'y': 0}
{'x': 4, 'button': 1, 'y': 1}
{'x': 4, 'button': 1, 'y': 4}
{'x': 4, 'button': 1, 'y': 3}
... move one pot ...
{'x': 9, 'button': 1, 'y': 2}
{'x': 493, 'button': 1, 'y': 1}
{'x': 1015, 'button': 1, 'y': 2}
{'x': 1857, 'button': 1, 'y': 1}
{'x': 1855, 'button': 1, 'y': 0}
... move the other pot ...
{'x': 1860, 'button': 1, 'y': 0}
{'x': 1860, 'button': 1, 'y': 3}
{'x': 1860, 'button': 1, 'y': 649}
{'x': 1858, 'button': 1, 'y': 1213}
{'x': 1862, 'button': 1, 'y': 1473}
{'x': 1865, 'button': 1, 'y': 2080}
{'x': 1858, 'button': 1, 'y': 2077}
... press the button ....
{'x': 1858, 'button': 1, 'y': 2080}
{'x': 1858, 'button': 0, 'y': 2080}
{'x': 1860, 'button': 0, 'y': 2077}
... release the button ...
{'x': 1858, 'button': 0, 'y': 2077}
{'x': 1859, 'button': 1, 'y': 2075}
{'x': 1863, 'button': 1, 'y': 2077}
{'x': 1862, 'button': 1, 'y': 2077}

Do you have a schematic for your joystick?

[dhylands]

And what version of the micropython firmware were you using?

Mine reports:

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Micro Python v1.3.1-75-g8369559 on 2014-09-13; PYBv1.0 with STM32F405RG
Type "help()" for more information.
>>> 

There was a bug in ADC related to using multiple channels fixed on June 16. So if your firmware is earlier than that, then I think you'll need to update the firmware.
https://github.com/micropython/micropython/pull/698

[riklaunim]

Kickstarter version, so I'll probably will have to update it and see if that helps

[riklaunim]

Firmware updated.

But firmware backup:

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sudo dfu-util --alt 0 --upload pyboard-original.dfu -s:524288

Gave:

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invalid dfuse address: :524288

And there is no description what's that address is and from where it comes from.

[dhylands]

There really isn't any reason to backup the firmware.

If you really need to go back, I'd be happy to build you the version that came with your board.

But there really isn't any reason to go back. If for some reason the very latest doesn't work, you can find a few days, plus several previous releases here:
http://micropython.org/download/

The 0.5 version of dfu-util fails the way you described. The latest version works properly.

You can grab source for dfu-util from here:
http://dfu-util.gnumonks.org/

and the build instructions are here:
http://dfu-util.gnumonks.org/build.html

I did the following (ubuntu 14.04)

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git clone git://gitorious.org/dfu-util/dfu-util.git
cd dfu-util
sudo apt-get build-dep dfu-util
sudo apt-get install libusb-1.0-0-dev
./autogen.sh
./configure  # on most systems
make

The compiled dfu-util will be in the src tree.

[riklaunim]

I was just doing what https://github.com/micropython/micropyt ... are-Update says to do :]

[blmorris]

I was just doing what https://github.com/micropython/micropyt ... are-Update says to do :]

From the page:

Previous releases of micropython are available from: http://micropython.org/download/ so performing a backup should be unecessary.

Looks like "should be necessary" should have been "shouldn't be necessary"
Guess I'll head over and see if I'm allowed to edit

[dhylands]

@blmorris - thanks for the typo correction

[riklaunim]

And the firmware update solves problems with ADC as well the Timer class allows better DC motor control -> article