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

Review of Hantek DSO8102E hand held oscilloscope

This article is a brief review of some issues that were found with initial testing of a Hantek DSO8102E two channel 100MHz hand held oscilloscope.

The DSO8102E is a member of the DSO8000 series (DSO8060, DSO8070E, DSO8100E, DSO8150E, DSO8200E), and shares most specifications across the series.

The specifications are very impressive, and price at just under $1000 for a Chinese brand seemed reasonable (hand held oscilloscopes are expensive compared to bench oscilloscopes).

The test scenario was a practical application, observation of the data traffic to/from a DHT22 temperature and humidity sensor in the project ESP8266 IoT DHT22 temperature and humidity – evolution 2. Continue reading Review of Hantek DSO8102E hand held oscilloscope

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

High gain external antenna for Wemos ProMini

I have some IoT projects that would benefit from range afforded by a better antenna than the on-board antennas in most ESP8266 modules.

The Wemos ProMini has an on-board IPX socket for an external antenna so it is a candidate. Note that a 0R 0603 resistor needs to be removed and another or a wire link soldered in to route the RF to the IPX socket.

Above the Wemos ProMini with a 7dBi SMA-RP antenna ($1.80) and flylead SMA-R(F) to IPX (M) ($1.00).  Continue reading High gain external antenna for Wemos ProMini

ESP8266 relay module review – Yunshan WiFi relay

After scouring eBay for a packaged esp8266 with 220V 10A relay, two products were identified:

  • Yunshan WiFi relay; and
  • LC Technology relay.

As is usually the case, finding a schematic and specifications is very difficult and the sellers were of no help (no surprises).

The LC Technology device was offered with indistinct pics that hinted it had a 8Mb flash chip, ESP8266EX processor, and a STC 15F104 8 bit processor on board for some unidentified purpose.

A schematic was eventually located for the Yunshan board, and from pics it appeared to have a 12E module on it which hinted the flash size.

A Yunshan module was purchased for about $10 posted, and it was indeed a 12E with flash-id 4016, so 4MB of flash memory.

The board does not incorporate a USB-TTL adapter which is a nuisance not just requiring an external adapter for programming, but there is no integration of the RTS and DTR signals as in the NodeMCU devkit. Adding a quality USB adapter (eg CP2102) would not increase the price a lot, you can keep the CH340G etc). Continue reading ESP8266 relay module review – Yunshan WiFi relay

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

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