Tag Archives: robotics

Compass Only Works on Pins 10 and 11 – Arduino/Software Serial

Hey everyone,

A bit of a confusing issue I ran into today. I couldn’t get my compass to work on any pins other than 10 or 11. Thankfully, there’s a fairly logical explanation:

Not all pins on the Mega and Mega 2560 support change interrupts, so only the following can be used for RX: 10, 11, 12, 13, 14, 15, 50, 51, 52, 53, A8 (62), A9 (63), A10 (64), A11 (65), A12 (66), A13 (67), A14 (68), A15 (69).

I ended up using pins 50 and 51 and it all worked fine. See the following links for more info:
https://www.arduino.cc/en/Reference/softwareSerial
https://arduino.stackexchange.com/a/35719/37451

Arduino GPS – Ublox NEO-M8N Flight Controller GPS w/Protective Shell for PIX PX4 Pixhawk

Hey everyone,

I recently purchased this GPS unit on ebay: http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItemVersion&item=272492032614&view=all&tid=1865626885017

Unfortunately, I didn’t do a lot of research before getting it and had a bit of trouble finding any spec sheets or documentation. Just in case anyone else has the same problem I’ve listed out everything I needed to get it running below.

This is the wiring info you’ll need:
– VCC: red
– GND: black
– TXD: yellow
– RXD: white
– SCL: green
– SDA: blue

The default baud rate was 38400.

This is the example I ended up using to get a quick test up and running. Ensure that you map the rx and tx pins correctly (arduino tx to gps rx, arduino rx to gps tx).


v#include
#include
/*
This sample sketch demonstrates the normal use of a TinyGPS++ (TinyGPSPlus) object.
It requires the use of SoftwareSerial, and assumes that you have a
4800-baud serial GPS device hooked up on pins 4(rx) and 3(tx).
*/
static const int RXPin = 11, TXPin = 10;
static const uint32_t GPSBaud = 38400;

// The TinyGPS++ object
TinyGPSPlus gps;

// The serial connection to the GPS device
SoftwareSerial ss(RXPin, TXPin);

void setup()
{
Serial.begin(115200);
ss.begin(GPSBaud);

Serial.println(F("DeviceExample.ino"));
Serial.println(F("A simple demonstration of TinyGPS++ with an attached GPS module"));
Serial.print(F("Testing TinyGPS++ library v. ")); Serial.println(TinyGPSPlus::libraryVersion());
Serial.println(F("by Mikal Hart"));
Serial.println();
}

void loop()
{
// This sketch displays information every time a new sentence is correctly encoded.
while (ss.available() > 0)
if (gps.encode(ss.read()))
displayInfo();

if (millis() > 5000 && gps.charsProcessed() < 10) { Serial.println(F("No GPS detected: check wiring.")); while(true); } } void displayInfo() { Serial.print(F("Location: ")); if (gps.location.isValid()) { Serial.print(gps.location.lat(), 6); Serial.print(F(",")); Serial.print(gps.location.lng(), 6); } else { Serial.print(F("INVALID")); } Serial.print(F(" Date/Time: ")); if (gps.date.isValid()) { Serial.print(gps.date.month()); Serial.print(F("/")); Serial.print(gps.date.day()); Serial.print(F("/")); Serial.print(gps.date.year()); } else { Serial.print(F("INVALID")); } Serial.print(F(" ")); if (gps.time.isValid()) { if (gps.time.hour() < 10) Serial.print(F("0")); Serial.print(gps.time.hour()); Serial.print(F(":")); if (gps.time.minute() < 10) Serial.print(F("0")); Serial.print(gps.time.minute()); Serial.print(F(":")); if (gps.time.second() < 10) Serial.print(F("0")); Serial.print(gps.time.second()); Serial.print(F(".")); if (gps.time.centisecond() < 10) Serial.print(F("0")); Serial.print(gps.time.centisecond()); } else { Serial.print(F("INVALID")); } Serial.println(); }

Output should be something like this:

DeviceExample.ino
A simple demonstration of TinyGPS++ with an attached GPS module
Testing TinyGPS++ library v. 0.92
by Mikal Hart

Location: -27.427371,153.028945 Date/Time: 9/10/2017 06:04:21.40
Location: -27.427371,153.028945 Date/Time: 9/10/2017 06:04:21.40
LocatiaonfTGS+wh atahdSmlesiTiGS+bay .2b a at
ain Da/ie/ ai .Da/Te 1tion: -27.427371,153.028945 Date/Time: 9/10/2017 06:04:21.60
Location: -27.427371,153.028945 Date/Time: 9/10/2017 06:04:21.60
LocaS+bay .2b a at
ain Da/ie/ ai .Da/Te 1tion: -.aeTm1.
ti:.atTm:7cation: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:21.80
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:21.80
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.00
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.00
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.20
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.20
Location: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.40
Locat/Te:/ an:3aTi: /1ain.atTm:7atn 3Dtie 1.cto.3teim 1.
ti: .aTim1aton: -27.427370,153.028945 Date/Time: 9/10/2017 06:04:22.40
Location: -27.427368,153.028945 Date/Time: 9/10/2017 06:04:22.60
Location: -27.427368,153.028945 Datn 3Dtie 1.cto.3teim 1.

One final thing to note is that the blue light will start to flash once the GPS has a lock. You'll need a pretty open space, mine didn't work inside but got a lock within 60 seconds outside.

Let me know if you have any questions or links to better doco!

TensorFlow – KeyError: “The name ‘import/input’ refers to an Operation not in the graph.

Hey everyone,

Just another small error I’ve run into while testing out Tensorflow’s label image example (Tensorflow/tensorflow/examples/image_retraining/label_image.py):

KeyError: "The name 'import/input' refers to an Operation not in the graph.

This one thankfully doesn’t seem to be my fault. In label_image.py change the following lines:

# Line 78-79
input_layer = "input"
output_layer = "InceptionV3/Predictions/Reshape_1"
 
# Change to this
input_layer = "Mul"
output_layer = "final_result"

Once that’s done just rerun your script and it should all work. Thanks to the following post for the solution: https://github.com/tensorflow/tensorflow/issues/12736

Tensorflow – No such file or directory

Hey guys,

Just a quick post on how to resolve an error I came across while testing out tensorflow:

Traceback (most recent call last):
  File "C:\Users\Chris-PC\Desktop\images-to-use\attempt2\tensorflow\examples\label_image\label_image.py", line 112, in <module>
    graph = load_graph(model_file)
  File "C:\Users\Chris-PC\Desktop\images-to-use\attempt2\tensorflow\examples\label_image\label_image.py", line 30, in load_graph
    with open(model_file, "rb") as f:
FileNotFoundError: [Errno 2] No such file or directory: 'tensorflow/examples/label_image/data/inception_v3_2016_08_28_frozen.pb'

All you need to do is download the following file and place it in the directory in the error message: https://storage.googleapis.com/download.tensorflow.org/models/inception_v3_2016_08_28_frozen.pb.tar.gz

Start a Script on Startup – Raspberry Pi

Hey guys,

Just thought I’d leave a couple of links to some guides I came across for setting up boot scripts on a raspberry pi.

Quick guide on how to get them running: http://www.instructables.com/id/Raspberry-Pi-Launch-Python-script-on-startup/

How to delay the boot process until the network is available: https://raspberrypi.stackexchange.com/a/45774

Raspberry PI Keeps Booting into the Login Screen

Hey everyone,

A bit of weird issue today – my RaspberryPi kept reverting to the login screen. To get around this, open command prompt from the login screen (ctrl + f1) and then run sudo rm ~/.Xauthority

Reboot and then it should work normally.

 

Exit Raspberry Pi Camera Preview

Hey everyone,

I ran into a bit of a weird issue with a raspberry pi camera preview today. After starting the preview I hit an uncaught exception which meant that exitPreview was never called.

To get around this use the terminal hotkey and kill the python process. Note that while you won’t be able to see the terminal, it will be running in the background.

https://www.raspberrypi.org/forums/viewtopic.php?t=152239&p=998212
ctrl + alt + t
pkill python
pkill python3