Tinker app not really doing anything (404 error)


I was having a play to see what I could do with the tinker app and from images it shows that you should be able to see the values being read on a given pin (e.g. http://docs.spark.io/#/start/tinkering-with-tinker-the-tinker-app). Now I don’t seem to be able to even get the user led to light, I go to D7, set to write and it shows a red circle round it but then if I click on it it says high followed by “core pin unknown error: 404”. This happens with any pin (digital or analog read or write).

Really appreciate any help.


Hi @Blacksheep,

The API will give you a 404 error if it thinks your core isn’t online, or if it thinks that function is missing. If you write and flash a program via the web IDE, it will replace tinker, and the digitalwrite / digitalread functions will no longer be available. You can always reflash tinker, or do a factory reset to get those back.

If you open up this url it’ll show you what functions and variables are exposed by your core.



Thanks David - I believe I’ve wiped the core, there response comes back as (obviously changing the ID):

“id”: “XYZ”,
“name”: “Core1 (sep ar)”,
“variables”: {},
“functions”: []

but behavior is as described before.

When you say wipe/reset do you mean something other than to:

void setup() {


void loop() {


Many thanks,


@Blacksheep: He means that, if you reprogrammed the Core to something other than the Tinker software, trying to use the iPhone app to control the pins will result in 404 errors. There are two different things you can do to get Tinker back onto your Core so that you can test its connectivity again.

First, if your Core is currently connected to the Spark network (breathing Cyan), you can go into the Spark Core app, click the list icon at the top left-hand corner of the app, click the arrow drop down next to your Core, and press the “Reflash Tinker” button. Make sure that the Connected: status reads “Yes”.

If that is not working, you can complete a factory reset for your Core. It’s really simple, and reverts the Core back to the firmware it was programmed with when you opened the box.

Try a factory reset. Hold down both buttons, then release the RST button, while holding down the MODE button. The LED should begin flashing yellow. Continue holding down the MODE button until you see the Core change from flashing yellow to flashing white. Then release the button. The Core should begin flashing blue after the factory reset is complete.

Let me know if any of that works for you!


Just unpacked my Spark board. It connects to the cloud fine, has a dandy name and is visible in both Android and iOS.

BUT… I have the exact same issue : digitalwrite of D7 doesn’t turn the blue LED on. I know it’s working because I saw it do a firmware update or something, and I saw it flashing in the corner.

So I followed Wills procedure to do a factory reset, but still no blue led i Tinker.

( I have junior Arduino experience)

Wellllllllll, that was a quick fix!

Turns out that if you remove the USB cable (hard power off) and restart the Spark, everything works fine! In Tinker I can now toggle D7, it show the words LOW and HIGH while toggling and the blue LED goes on and of, pfewwwww!

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Thanks guys - just being a little special ATM. Appreciate the pointers.

Any way you could add this to the IDE (say as a reset option)?

I’ll pop that in the feature request backlog for the build IDE, I think that would be nice to either have parity with the Tinker mobile app, or to make it clear which cores were flashed most recently with which apps.


Hey folks, I’d like to throw in another option to reflash the Tinker FW on your Core, that was there from the word go - at least on the Android versions I used to use.
Once you got your Core(s) registered with :spark: Spark Tinker App you should be able to reflash Tinker FW by just selecting the apropriate named menu item “Reflash Tinker” in the Apps menu (on the Tinker “Pin-Control-Screen”)

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