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D1 Mini X-Pad Shield

Adds some buttons to your ESP8266 board.

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I sell on Tindie

This shield for the D1 Mini ESP8266-based development board adds a joystick and three buttons, so that you can implement menus or games on your device easily.

d1-xpad.zip

Gerber files.

Zip Archive - 72.20 kB - 01/25/2017 at 12:06

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  • Version 6.0

    ðeshipu6 days ago 4 comments

    After using an ATtiny24 for handling buttons in #Micro:Boy I decided that this is also the way to go with the X-Pad shield. I designed version 5.0 which used the same buttons and layout as 4.0, but a different chip, and I tested the firmware with it. Turns out that it works very well, and does de-bouncing and buffering for you, so that you don't have to poll the chip frantically for presses, afraid that you miss any. All button presses now wait nicely in the buffer until you read them. The shield looked like this:

    But then I have some problems with the shields I sold on Tindie (due to poor solder joints on the buttons), and I removed the shield from my store. I decided to work on the design a little bit more and make a version that will really be the best I can make. Behold, version 6.0:

    It's bigger than the original X-Pad shield, and has mounting holes. It also has all the components, except buttons, on the back, and away from the middle part of the board — so it can lie flat against the D1 Mini and other shields. It also has friction-fit headers, so no soldering is necessary and you can add it to another shield easily, like this:

    There are also two headers for popular display modules. One for the 128×128 ST7735R module (you might need to trim that corner):

    And one for the popular SPI-based OLED modules, such as SSD1331 or SSD1306:

    I still need to add some last finishing touches to the firmware and test it all properly, and it's going into my Tindie store.

  • Version 3.0

    ðeshipu01/25/2018 at 20:41 0 comments

    I have been working a little on this project in the recent months, designing a new PCB using different parts and so on, but I didn't really have time to assemble and test it properly. Recently I found the PCBs in a drawer, found the matching parts, and decided to give it a go. Behold, version 3.0:

    and the back side:

    Read more »

  • Example Code

    ðeshipu10/11/2017 at 18:13 0 comments

    There has been some questions as to how to actually handle this shield in the code, so I'm providing some simple examples:

    MicroPython

    from machine import I2C, Pin
    import time
    i2c = I2C(sda=Pin(4), scl=Pin(5))
    while True:
        print(hex(i2c.readfrom(0x20, 1)[0]))
        time.sleep(1)

     NodeMCU

    i2c.setup(0, 1, 2, i2c.SLOW)
    tmr.alarm(0, 1000, 1, function ()
        i2c.start(0)
        i2c.address(0, 30, i2c.RECEIVER)
        print(string.toHex(i2c.read(0, 1)))
        i2c.stop(0)
    end)

     Arduino

    #include <Wire.h>
    void setup() {
        Wire.begin();
        Serial.begin();
    }
    void loop() {
        Wire.requestFrom(0x20, 1);
        Serial.print(Wire.read(), HEX);
        delay(1000);
    }

     All of the above examples scan the buttons once a second and print their state as a hexadecimal number on the serial console.

  • Buy it on Tindie

    ðeshipu10/09/2017 at 15:06 0 comments

    I have added this to my shop at Tindie, so you can now buy it: https://www.tindie.com/products/deshipu/x-pad-20-buttons-shield-for-d1-mini/

    It's the cheapest shield I have made so far. I am not entirely happy with it yet (the buttons are too small and I should have put the chip on the underside), but it's actually very useful, so why not let people get it. It goes well together with the official OLED shield:

  • Pull-ups? We need no @#$@$ pull-ups!

    ðeshipu09/28/2017 at 09:50 3 comments

    Turns out that I have over-engineered this shield a little bit — I wanted to make sure the pins are pulled up when the buttons are not pressed, so I added a pull-up resistor to each button. But looking at the #LAMEBOY - another ESP12 handheld project, I noticed that @davedarko didn't use any pull-ups, and it works reliably for him. We dived into the datasheet a bit and did some experiments, and it turns out you really don't need them. So now I'm leaving the pads for the pull-up resistors un-populated. Perhaps I will design another version of the PCB, with the chip on the bottom side and without any pull-ups whatsoever, but for now this simplified second version works well for me.

  • New Version Assembled

    ðeshipu09/07/2017 at 11:41 1 comment

    It took me a while to assemble this, because by mistake I used 4x4mm button footprints instead of the 5x5mm, so I had to order matching switches. But it's there, and it's working. Here's a comparison photo with the old version:


    The friction-fit alternating pins work really well, and make the whole thing much smaller. The chip, even though SMD, is still pretty huge — I'd love to find a small, preferably QFN, chip that can handle buttons over I²C, but I'm too lazy to look for it specially. The buttons are much more convenient than the old "joystick", even though they are still not very friendly to your fingertips.

  • Upgrade

    ðeshipu08/03/2017 at 10:40 0 comments

    I went ahead and upgraded the design of this shield a little bit. It now uses all SMD components (including the PCA8574 chip), has all parts on one side, and uses buttons in place of that tiny joystick thing. Oh, and I dropped the address selection jumpers, since you are not going to have more than one of this on a single dev board anyways.

    The pin headers now are staggered for a pressure fit, so that you should be able to put this between your dev board and a display shield without additional headers increasing the height.

  • Proper Buttons

    ðeshipu02/25/2017 at 12:57 1 comment

    The first prototype used whatever buttons I have at hand at the moment — they weren't very good. Now the buttons I ordered for it arrived, so I assembled a second prototype. Unfortunately, the buttons I ordered are too big, so I had to wrap their legs under them. But it works and doesn't look too bad.

  • Done.

    ðeshipu01/25/2017 at 12:03 2 comments

    The PCB arrived from OSHPark, and it works. You can order it at: https://oshpark.com/shared_projects/J8a9MVbO

    I'm not happy with the buttons -- I used some cheap SMD buttons that I had on hand, but they are not really designed for being pushed directly by fingers. I might try gluing something on top of them, so they work better.

    I used a chip socket for the chip, and the whole thing is rather high. In the future, I would probably use a different chip, in SMD version, and maybe even put it on the bottom.

    All in all, it works well enough and I'm quite happy with it.


  • Button Layout

    ðeshipu01/10/2017 at 22:42 0 comments

    need an easy way to add user input capabilities to my D1 Mini boards. A joystick and some buttons would be probably the most versatile approach -- I could also use an encoder, like I did for #Nano TTY, however, that works well for menus, but not so good for games, and I want to try making some games too in the future. So I need something roughly like a game pad. A 4-way joystick, at least two buttons (accept and back), possibly a third button for start/settings, and possibly the fire button on the joystick. That's eight buttons together. Since the ESP8266 doesn't have a lot of GPIO pins, I will probably use a port expander -- this way I can just connect it to the I²C bus.

    Next, I need to choose the layout for this shield. Using a standard D1 Mini shield shape doesn't seem like a good idea, because I want to be able to stack this with the display and led matrix shields. I could probably use the "double" shield for this, but it would be better if the buttons and joystick were accessible even if it's not the top shield.

    I considered several options:

    I even considered more exotic solutions, like putting all the buttons on the sides of the board, so that they are accessible -- but that's hard to do with the joystick, and makes it too easy to press the reset button accidentally.

    I finally decided to use the last design on that image above. Yes, it's going to be problematic with the double shield -- but that can be worked around by making one of the stacks higher.

    I couldn't sleep last night, so I got up and designed the PCB for this in Fritzing. I'm going to use the good old PCF874 port expander, even though it's a bit dated and weird to use -- but at least it's easy to get. Routing everything properly on such a small board was a bit tricky, but finally I even managed to add the footprints for the I²C pullup resistors and the address selection jumpers. I'm pretty happy with how it came out:One trick I had to do -- I put the joystick up-side-down. It won't affect anything, but it makes it easier to route the ground pin for it. Now just waiting for the PCB.

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Jon Raymond wrote 10/11/2017 at 17:12 point

Picked up one of these on Tindie, cool little board. Any demo code available for it?

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ðeshipu wrote 10/11/2017 at 17:50 point

Hi, thanks for your order. You literally just read a single byte over I²C. I will post some example code here for the most popular platforms.

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Starhawk wrote 01/10/2017 at 23:37 point

I spy with my little eye... a typo. Google helped me on this one.

PCF8574, not PCF874. Proof --> http://www.nxp.com/products/interfaces/ic-bus-portfolio/ic-general-purpose-i-o/remote-8-bit-i-o-expander-for-icbus-with-interrupt:PCF8574AP

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ðeshipu wrote 01/11/2017 at 02:51 point

Good catch, thanks, fixed. What is more important, though, I noticed that one of the traces is going too close to the joystick's mounting hole. I fixed that too, however, the PCB is already ordered. I guess I will fix it with some wire if it doesn't work.

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davedarko wrote 01/25/2017 at 13:03 point

there's still one in the log "Button Layout" ;)

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ðeshipu wrote 01/25/2017 at 16:45 point

Thanks, fixed.

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