Troubleshooting

Posted on Mon 10th, August 2015

• #1

user52526

>digitalWrite(A4,1);
=undefined
>digitalRead(A4);
=0
>pinMode(A4, "input_pulldown");
=undefined
>digitalWrite(A4,1);
=undefined
>digitalRead(A4);
=0
>pinMode(A4, "input_pullup");
=undefined
>digitalWrite(A4,1);
=undefined
>digitalRead(A4);
=0
>

• #2

DrAzzy

What's connected to A4? Could it be shorted to ground?
• #3

Gordon

So the issue is that the last digitalRead should return 1? As discussed in another thread on here very recently, it's not a massive surprise that the first digitalRead returns 0, as before you call pinMode, digitalRead will make sure the pin is an input, which would make the voltage on it more or less random.

Is A4 connected to anything? Which board are you using, and do you have up to date firmware?
• #4

Gordon

Just tried it here and it works fine for me.
• #5

user52526 in reply to @Gordon

I have to date firmware and A4 is connected to a diode. I'm using this board: http://www.espruino.com/EspruinoBoard
• #6

user52526

All good in the hood, thanks guys!
• #7

Gordon

Was the diode connected to GND on the other side?

Post a reply
- Bold
- Italics
- Link
- Image
- List
- Quote
- code
- Preview
Formatting Help

Don't worry about formatting, just type in the text and we'll take care of making sense of it. We will auto-convert links, and if you put asterisks around words we will make them bold.

Tips:

Create headers by underlining text with ==== or ----

To *italicise* text put one asterisk each side of the word

To **bold** text put two asterisks each side of the word

Embed images by entering:
![](https://www.google.co.uk/images/srpr/logo4w.png)
That's the hard one: exclamation, square brackets and then the URL to the image in brackets.

* Create lists by starting lines with asterisks

1. Create numbered lists by starting lines with a number and a dot

> Quote text by starting lines with >

Mention another user by @username

For syntax highlighting, surround the code block with three backticks:

```
Your code goes here
```
Just like Github, a blank line must precede a code block.

If you upload more than 5 files we will display all attachments as thumbnails.

For a full reference visit the Markdown syntax.

Troubleshooting

About

Troubleshooting

Actions

Troubleshooting

Formatting Help

About

Troubleshooting

Actions

Espruino