Review of inexpensive Chinese LAN cable tester

I bought an inexpensive LAN cable tester to give to my daughter.

Above is the sellers pic, the specifications states that it checks data wires 1-8 and the shield / ground connection of STP cables.

On test, it failed to show the shield connection on an STP cable, the LED did not light on either the master or the slave unit.

I tore it apart to see if it was worth getting a replacement. Continue reading Review of inexpensive Chinese LAN cable tester

ESP8266 remote power display for energy monitor – EV3 – 5V display

ESP8266 remote power display for energy monitor – EV3 documented an evolved design for a real power display using emontx3 / emonhub / mqtt. This article documents an adaptation to use a 5V display module (for higher brightness). The ESP8266 is not 5V tolerant, so a logic level converter is needed.

Hardware

The remote power display uses a Wemos D1Pro module, a common 5V 4 digit 14.2mm seven segment LED module with 74HC595 shift register per digit, and a common 3V/5V logic level converter between them.

Above, the Wemos D1Pro with wires attached to the HSPI and power pins. A 1k pull=down resistor is soldered between the D8 and GND pins under the D1Pro board. Continue reading ESP8266 remote power display for energy monitor – EV3 – 5V display

ESP8266 remote power display for energy monitor – EV3

ESP8266 remote power display for energy monitor and ESP8266 remote power display for energy monitor – EV2 documented a design and some variations for a real power display using emontx3 / emonhub / mqtt. This article documents an evolution to use the ESP8266 HSPI port for much higher speed writing of the LED display, high enough to be later adapted for multiplexed displays.

Hardware

The remote power display uses a ESP8266-12E devkit 1.0 module, a common 3.3V 4 digit 14.2mm seven segment LED module with 74HC595 shift register per digit. The particular LED module has sufficient space to mount the ESP8266 inside the module.

Above, the interior of the module that suits the implementation. Continue reading ESP8266 remote power display for energy monitor – EV3

ESP8266 remote power display for energy monitor – EV2

See ESP8266 remote power display for energy monitor – EV3 for an update…

ESP8266 remote power display for energy monitor documented a design and some variations for a real power display display using emontx3 / emonhub / mqtt. This article documents a simple compact implementation.

Hardware

The remote power display uses a ESP8266-12E devkit 1.0 module, a common 3.3V 4 digit 14.2mm seven segment LED module with 74HC595 shift register per digit. The particular LED module has sufficient space to mount the ESP8266 inside the module.

Above, the interior of the module that suits the implementation. Continue reading ESP8266 remote power display for energy monitor – EV2

ESP8266 remote power display for energy monitor

This article documents remote power display for an energy monitor system based on emontx3 / emonhub / mqtt.

The remote power display connects via WiFi and subscribes to a topic on a MQTT server, updates are published every 10s with data from the emontx3 by emonhub.

Hardware

The remote power display uses a Wemos D1Pro ESP8266 module, a common 4 digit 14.2mm seven segment LED module with 74HC595 shift register per digit, and a simple 3V/5V level converter between the two (see above shrink wrapped in the cable from the D1Pro to the display).  Continue reading ESP8266 remote power display for energy monitor

ESP8266 IoT DHT22 temperature and humidity – evolution 3

This article documents a first project with the Espressif ESP8266 in its third evolution (based on ESP8266 IoT DHT22 temperature and humidity – evolution 2).

The objective is a module that will take periodic temperature and humidity measurements, and in this evolution publish them using a RESTful API.

Evolution 3

The example platform used in this article is a Wemos D1Pro. In this case, the D1Pro is configured for an external antenna, and a modification is made to the board to add a 1N34A diode for the deep sleep reset circuit (NodeMCU devkit V1 deep sleep). A three pin right angle header to the top of the board (as seen) and another on the underside on the opposite edge to get GND, +5, +3, and D4 for the DHT22 data wire. There is less than $20 in parts in the pic above. Continue reading ESP8266 IoT DHT22 temperature and humidity – evolution 3

ESP8266 IoT DHT22 temperature and humidity – evolution 2

This article documents a first project with the Espressif ESP8266 in its second evolution.

The objective is a module that will take periodic temperature and humidity measurements and publish them to an MQTT message broker.

This inital implementation is very basic, it is largely configured in code, though it does use DHCP. Later extensions might include a web interface for configuration of WLAN parameters etc, but for the moment the emphasis is assessment of reliability given some reports on the ‘net.

Evolution 2

The original design embedded key configuration variables in the main source code for simplicity in getting the code working.

Evolution 2 separates configuration variables from code, and provides a web interface for configuring the most common variables. The screenshot above shows the configuration screen including the use of a datalist on the SSID input field.

Hardware

A module was purchased with on board CP210x USB to serial chip. The only other component needed was the DHT22 digital temperature and humidity sensor.

NodeMCU was chosen for the ESP2866 firmware because of the inbuilt support for ‘interesting things’, including the DHT22.

Above is a breadboard of the system for development. The board had a 4MB (32Mb) flash chip on it. Continue reading ESP8266 IoT DHT22 temperature and humidity – evolution 2

NodeMCU devkit V1 deep sleep

Low cost implementations of the NodeMCU devkit V1.0 abound on eBay, and are featured in lots of projects.

Deep sleep mode is used in a lot of projects, the MCU is but into sleep mode and it requires circuitry so that the  from the /WAKE pin (D0, GIO16) can pull the /RST pin to wake the processor up.

The problem

The common schematics as above simply wire /WAKE pin (D0, GIO16) to /RST (yellow wire), but this disrupts operation of the reset circuit, which degrades development productivity. Continue reading NodeMCU devkit V1 deep sleep

ESP8266 IoT DHT22 temperature and humidity

This article documents a first project with the Espressif ESP8266.

The objective is a module that will take periodic temperature and humidity measurements and publish them to an MQTT message broker.

This inital implementation is very basic, it is largely configured in code, though it does use DHCP. Later extensions might include a web interface for configuration of WLAN parameters etc, but for the moment the emphasis is assessment of reliability given some reports on the ‘net.

Hardware

A module was purchased with on board CP210x USB to serial chip. The only other component needed was the DHT22 digital temperature and humidity sensor.

NodeMCU was chosen for the ESP2866 firmware because of the inbuilt support for ‘interesting things’, including the DHT22.

Above is a breadboard of the system for development. Continue reading ESP8266 IoT DHT22 temperature and humidity

ADS1115 ADC checkout – #1

I have application for an analogue to digital converter (ADC) in a noisy environment, so a possible solution is to place an ADC module very close to the analogue sensors and use some form of digital connection back to a microcontroller. A possible protocol is I2C, and has the advantage that several ADC modules can be attached to the same bus, along with other peripherals Eg LCD.

ads1115-00The above ADS1115 modules have four input channels, 16 bit conversion, flexible input mux, and were available on eBay for less than A$4, so worth a try.
Continue reading ADS1115 ADC checkout – #1