Tech Diary

ESP-01 is a simple ESP8266 module which can be purchased cheaply from Aliexpress. At one of promotion, I purchased an ESP-01 for just S$1.97. That's very cheap for a wifi enabled microcontroller. An ESP-01 can be a WIFI bridge for non-connected microcontroller such as Arduino UNO, Mega, Nano etc. Communication between the microcontroller can be done using the serial link between them. I have written a post on this using ESP-Link to connect to an Arduino Pro Mini. Together with the client library provided, the Pro Mini can easily transfer sensor data via MQTT. http://iotdiary.blogspot.sg/2017/09/using-esp-link-transparent-bridge.html For the most part, once the firmware is in place, normally I will use OTA to update. Sometimes, I wanted to reuse the same controller for another firmware and I have rewired up the controller for reflashing. This makes it very inconvenient to use. Recently, I bought a USB ESP-01 adapter thinking that my problem is solved. When I received it and r...

One of the difficulties I had with the common IR transmitter module block from Arduino kit is it is not powerful. It can only transmit from a distance of about 1 m and the angle is very narrow. I need an effective distance of more than 3m and a wider angle and I wanted to use Tasmota as the bridge so that I can send the IR commands from my PC or another remote non-IR device. The circuit for the super IR transmitter is as follows. On the web, I have found 2 approaches: connect multiple IR LEDs in series or parallel. The parallel configuration will provide more current to the LEDs and the series configuration will provide less current. I chose the series circuit because the resistance in the parallel circuit cannot be matched properly and the LED with the lowest resistance will get more power than the other which may result in 1 IR Led brighter than the other. I managed to find a super bright IR transmitter LED in Aliexpress. The LED has a blueish tint compared to the...

For this article, I am writing about the 3 sites where I have purchased most of the Home Automation project parts. Online shopping for China goods in Singapore is a wonderful experience. The parcel delivery services here are reliable and reasonably fast. So far I have not encountered a single package lost. My main consideration for online shopping is the ability to pay with maximum convenience, minimum fee and delivery to your doorstep. Taobao Taobao is the de facto shopping for those people in living China. In the early days, for those staying outside China, the only way to buy from Taobao was to go through agents who ordered the products on your behalf and charge a fee. Taobao recently announced a tie-up with Lazada (an online shopping portal bought over by Alibaba). Most of the fanfare is Lazada provides a Taobao link in Lazada portal . Actually, the main benefit is that I can order from Taobao main site and send over to Singapore via Lazada. Although in Taob...