I just received my NodeMCU Motor Shield to go with my NodeMCU v1 ESP12e development board and robot chassis. So the board has a bunch of screw terminals on it – A+, A-, B+ and B- to connect two motors, and then VM/GND (up to 9v for the microcontroller) and VIN/GND (up to 36v for the motors). However the mostly undocumented feature is that if you jumper the VIN/VM pins near to the power switch, you can supply up to 9v to VIN/GND and it will feed that into the motors and also into the NodeMCU’s 3.

Whilst looking for something I could do with an ESP-01 and sleeping/batteries, I found this, which itself was inspired by this (which I couldn’t get to work!) Essentially you power on the ESP-01 by pressing a button. Now whilst that sounds lame, the clever part is that once its on, you can do whatever you like e.g. post to a website, and then turn the unit back off (by setting GPIO2 and CH_PD low) until the button is pressed again.

I’ve finally gotten around to making a web frontend for my Raspberry Pi & Arduino wireless sensor network. I chose Shopify’s Dashing dashboard, as its opensource and can be installed locally and not via some cloud crap. Essentially you have a HTML template into which you feed JSON data. I got a bit tied up in the JSON formatting so it took longer than it should have to get working (about 3 hours) but once I realised that most of the job placeholders were a single line of JSON, and not a whole entity, it was quite straightforward.

I’ve finished my obstacle avoiding robot project. Basically its an ATmega328p microcontroller that uses an HC-SR04 ultrasonic sensor to detect obstacles. The head moves using an SG-90 servo and a L293D dual H-bridge drives the two motors, using a library I’ve written and put on GitHub. The whole robot is powered by two 3.7v 18650 Li-Ion batteries with a DC/DC converter that drops it to 6v for the motors and a diode (and smoothing cap) to drop it further to 5v for the microcontroller and servo.

I’ve made my Pro Micro/Mini ISP breakout board and Raspberry Pi nRF24L01+ breakout board as per my previous post and decided to get on with trying out RF24Mesh. The problem there was that with the newer commits to RF24 and RF24Network, I was getting no response from the Arduino’s to the RPi. After some debugging with the author of the libraries on GitHub, we managed to find the culprit – not really the clone issue or the differing module issue, but actually a bit of an oddity in how dynamic payloads and dynamic ACKs work together.