Author: Chris Owens

Unsupported_Grant_Type – MVC Web Api (error)

Hi everyone,

I ran into the following error while attempting to authenticate using .NET Web Api:

POST http://localhost:63720/Token HTTP/1.1
Host: localhost:63720
Content-Type: application/json
Content-Length: 0
HTTP/1.1 400 Bad Request
Content-Type: application/json;charset=UTF-8
Date: Mon, 16 Apr 2018 14:18:06 GMT
Content-Length: 34

{“error”:”unsupported_grant_type”}

This one was pretty straight forward. Ensure that have the correct content-type:

Content-Type: application/x-www-form-urlencoded

And finally, ensure that you provide a grant type in the request body:

grant_type=password&username=test_username&password=test_password

Thanks to the following stackoverflow post for the info: https://stackoverflow.com/a/29261024/522859

An error occurred (UnrecognizedClientException) when calling the CreateFunction operation: The security token included in the request is invalid.

Hi everyone,

I ran into the following error today while attempting to create a Lambda function using the CLI:

An error occurred (UnrecognizedClientException) when calling the CreateFunction operation: The security token included in the request is invalid.

The first thing to check is that your aws config is setup correctly. For me this is under c:userschris-pc.aws.

If that looks fine, double check that the associated user has the correct rights by viewing the IAM page in the server console: https://console.aws.amazon.com/iam/home

Finally, ensure that the user has programmatic access and that the keys match those in your config.

FAILED. Reason: Requires capabilities : [CAPABILITY_IAM] – AWS SAM

Hi everyone,

I ran into an error today while trying to deploy using AWS SAM:

aws cloudformation deploy –template-file C:Usersxxxserverless-output.yaml –stack-name events-app
Failed to create the changeset: Waiter ChangeSetCreateComplete failed: Waiter encountered a terminal failure state Status: FAILED. Reason: Requires capabilities : [CAPABILITY_IAM]

The solution is pretty straightforward. You need to explicitly add –capabilities CAPABILITY_IAM to you command:

Serverless Offline Error – sls offline start

Hi everyone,

I ran into the following error while trying to start serverless offline:

serverles events.js:160
throw er Unhandled ‘error’ event spawn java ENOENT at exports._errnoException (util.js:1020:11) at Process.ChildProcess._handle.onexit (internal/child_process.js:197:32) at onErrorNT (internal/child_process.js:376:16) at _combinedTickCallback (internal/process/next_tick.js:80:11) at process._tickDomainCallback (internal/process/next_tick.js:128:9)

Solution
It turned out to be because I didn’t have the Java JDK installed.

I expect you’ll have the same problem if the command prompt doesn’t have access to the JAVA_HOME variable or if your JAVA_HOME path isn’t set correctly.

AWS CLI Copy from Bucket – An error occurred (AccessDenied) when calling the CopyObject operation: Access Denied

Hi everyone,

I ran into the following error while trying to copy files from one bucket to another using the AWS CLI:

An error occurred (AccessDenied) when calling the CopyObject operation: Access Denied

Thankfully this one is pretty self-explanatory. My user was missing the permissions required to view the bucket.

To see your user: aws configure list
To add permissions: view the IAM Management Console

Thanks,
Chris

AWS CLI Copy to Bucket – Could not connect to the endpoint URL

Hi everyone,

I ran into the following error while attempting to copy files to a bucket via the AWS CLI:

Could not connect to the endpoint URL: “https://wildrydes-us-east-1.s3.wildrydesxxxx.amazonaws.com/?prefix=WebApplication%2F1_StaticWebHosting%2Fwebsite%2F&encoding-type=url”

The solution turned out to be pretty straight-forward. The region on the cli-config was set incorrectly. For example, mine was set to “Sydney” instead of “ap-southeast-2”. Type “aws configure list” to check what yours is set to.

Thanks to the following stackoverflow post for the info: https://stackoverflow.com/a/40411174/522859

Using INA219 (GY-219) with the Raspberry Pi

Hi everyone,

I’ve just setup an INA219B Voltage/Current sensor on my RaspberryPi. Just thought I’d link the tutorials and libraries I used – there’s a lot of really useful info out there.

Install the following library via git: https://github.com/chrisb2/pi_ina219
sudo pip3 install pi-ina219

Follow this tutorial: https://www.rototron.info/raspberry-pi-ina219-tutorial/

Misc Notes

  • Common ground is required
  • Vin – and Vin+ are attached to +, neither goes to ground

Custom Sensor Address
na = INA219(SHUNT_OHMS, MAX_EXPECTED_AMPS, address=0x41)

Can be configured via the following:

https://www.rototron.info/raspberry-pi-ina219-tutorial/
https://www.rototron.info/raspberry-pi-ina219-tutorial/

Enable Low Power Between Reads
ina.configure(ina.RANGE_16V)
while True:
print "Voltage : %.3f V" % ina.voltage()
ina.sleep()
time.sleep(60)
ina.wake()

If you’re getting the following error:

OSError: [Errno 121] Remote I/O error

Run the following command:

i2cdetect -y 1

And check to ensure that your device is showing up on 40. If it’s a different number you’ll just need to update the address in your code e.g. (0x40, 0x41, etc.)

Mini-360 DC-DC Buck Converter – Incorrect Voltage 10v Instead of 5v

Hi everyone,

I’ve been playing around with a few DC-DC buck converters similar to these ones: https://www.amazon.com.au/UEB-Power-Converter-Module-Supply/dp/B078CXHWXC/ref=sr_1_fkmr1_1?ie=UTF8&qid=1519030369&sr=8-1-fkmr1&keywords=mini+360+buck+converter

I had expected 5v output from my 12v supply but when I hooked it up to a multimeter I found I was getting just over 10v. This would fry pretty much everything in my circuit so I was pretty worried.

After a bit of research, I came across a thread on eevblog that mentioned a screw for adjustment. Looking closely you can see that there is a small screw on the side of the chip. Turning this quarter of a rotation anti-clockwise put mine at exactly 5.04 volts.

A few other small tips:

  • The thread seems to indicate that some models require a lot more turning (up to 30 seconds for one poster).
  • I had to push down fairly hard to get it to actually turn the part underneath instead of just the metal cover

Hopefully this helps someone else out!

Eevblog: https://www.eevblog.com/forum/beginners/dc-dc-buck-converter-step-down-module-lm2596-power-supply/

Thanks,
Chris

Duinotech Hall Effect Sensor with RaspberryPi

Hi everyone,

This is just a quick post to cover how the Duinotech hall effect sensor module (XC-4434) can be hooked up to a RaspberryPi.

Sample Code

The code below will output a zero when the sensor is activated by a magnet, otherwise a zero.


import time
import datetime
import RPi.GPIO as GPIO

# Define constants
BUCKET_HALL_EFFECT_SIG_PIN = 14

# Setup GPIO pins
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
GPIO.setup(BUCKET_HALL_EFFECT_SIG_PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP) # Important

while True:
print(str(GPIO.input(BUCKET_HALL_EFFECT_SIG_PIN))
time.sleep(0.5)

Wiring

Example

When near a magnetic field the light on the sensor will turn on. If you’re using the sample code above, a zero will be shown when close to a magnet, otherwise a 1.

Misc

Purchased from: https://www.jaycar.com.au/arduino-compatible-hall-effect-sensor-module/p/XC4434

Spec Sheet: Z7275

AttributeError: module ‘serial’ has no attribute ‘SerialException’ – Python 3.5

Hi everyone,

A quick fix for an error I ran into while updating to Pyhton 3.5.2:

AttributeError: module 'serial' has no attribute 'SerialException'

I needed to add pyserial:

pi@raspberrypi:~/Desktop/piscripts/get-commands $ sudo pip3.5 install pyserial
Collecting pyserial
  Downloading pyserial-3.4-py2.py3-none-any.whl (193kB)
    100% |████████████████████████████████| 194kB 530kB/s
Installing collected packages: pyserial
Successfully installed pyserial-3.4

Thanks to the following link: https://stackoverflow.com/a/47562659/522859