We received our ESP8266 NodeMCU several months ago it has been difficult to find a working example of Hardware PWM to generate crisp Infrared carrier signals. Most posts we have read suggest that there is no PWM readily available on any of the supported platforms. As we have already shown with Arduinos and the Particle Photon we figured it would be possible to use a spare UART pin on the ESP8266 NodeMCU to achieve our goal. After some initial success we encountered some watchdog timeouts/resets and it seemed like the uPWM hack would not be possible on the ESP8266 Node MCU platform. For a few weeks we ‘parked’ the effort and today we decided to try again with all of the latest and updated firmware available from the ESP8266 community via the Arduino IDE. This time we were successful and the ESP8266 NodeMCU Backdoor uPWM Hack for IR signals using works!
One of the most popular projects involving Infrared remote control, is to use an Arduino to control an Air conditioner (AC) system. However, AC signals are usually very long and take up a lot of SRAM on a standard Arduino. Experienced users will go about reverse engineering the AC protocol to make the sketch fit within the 2K Bytes of SRAM. Many hobbyists will struggle, even with the help of tools like AnalysIR to guide them. In this post we cover sending long AC Signals from Flash with IRremote. IRremote (along with IRLib) is a popular open-source library for sending and receiving IR remote control signals with Arduino. The demo code covered in this sketch extends our previous sendRAW example by demonstrating how to store many long AC signals in Flash with little or no SRAM overhead.
Marco is a volunteer for an organization (NSW Australia) that builds custom aids for people with disability, and has recently been looking at a project to create a ‘very large button’ IR remote control for a cable TV Set Top Box (STB). The custom unit needed basic functions (Channel Up/Down, Volume Up/Down and Power On/Off). Commercially available large button remotes have buttons that are still too small and/or they have too many buttons. Soon he hit a roadblock trying to capture some difficult Foxtel signals and searched all over the web looking for a solution. Needless to say, nothing worked out for him until he came across AnalysIR via Google. Once he started Troubleshooting the Big Button Infrared remote control with AnalysIR the root cause of his problems became obvious.
One of our users from Italy, Guido, was tasked with upgrading an old in-house WRC system to allow the team of Sport’s Journalists to access the rack of satellite receivers relaying the various sports events around the building. The challenge is that all of the STB (Set Top Boxes) are located in a dedicated room away from the Journalist’s desks and it is impractical for them to manually change the stations when working to tight deadlines. Previously there was a system in place to remotely switch feeds, but Guido needed to upgrade the system to handle the ever growing number of devices and Infrared protocols. Luckily, he found AnalysIR during his research to implement ‘a hack for Hacks using AnalysIR‘.
In this blog post we follow up on our recent article about generation of infrared PWM from the Photon’s UART where we suggested that it may be possible to achieve something similar with the Arduino. In our previous attempt the Arduino was only able to generate PWM at 40 kHz and 33 kHz using the same approach. After some investigations we discovered a new approach which provides an even better set of results using the Arduino’s USART. Yes, we were able to generate 30, 33, 36, 38, 40 , 56 and surprisingly the illusive 455 kHz which was not possible on the Photon (using this approach). Read on for the details. Readers should also study our original series of articles on ‘softPWM‘ for a better understanding of the source code which can be downloaded below.
This post is the second in a two-part series about Reverse Engineering AC Infrared protocols. This time we look at the Mitsubishi Air Conditioner IR Protocol. The project was undertaken by two of our users in France (Vincent & Mathieu), with the help of AnalysIR, who collaborated to reverse engineer this Mitsubishi and previously the Panasonic AC Infrared protocol, both examples of the more challenging AC Infrared protocols. Not only did they identify the individual field codes & checksum but also provided some impressive documentation. Detailed information is available via GitHub which is linked below. This 288 data bit Mitsubishi AC Infrared protocol is composed of two consecutive frames. Both frames are always identical for each signal sent. In common with most AC units the complete settings are sent with every IR signal (temperature, fan, swing etc…). AnalysIR was used to record and turn the signal into HEX/Binary format from which the reverse engineering of the individual fields was tackled.
Recently, two of our users in France (Vincent & Mathieu) collaborated to reverse engineer the Panasonic AC Infrared protocol, one of the more challenging AC Infrared protocols using AnalysIR. Not only did they identify the codes & checksum but also provided some impressive documentation and full source code to help others. Detailed information is available via GitHub which is linked below. This 216 data bit Panasonic AC Infrared protocol is composed of two consecutive frames. The first frame remains constant for every command sent to the AC unit. In common with most AC units the complete configuration is sent with every IR signal (temperature, fan, swing etc…). AnalysIR was used to record and turn the signal into HEX/Binary format from which the reverse engineering of the individual fields was tackled.
Anyone who has tried controlling an Air Conditioner unit using an Arduino, USB IR Toy, RPi or any MCU will know how difficult it can be to record the longer infrared signals they use. Typical TV systems use IR signals circa 32 bits long, while this Chigo AC unit uses a signal with 197 marks & spaces (or 97 data bits). One of our users, Sertunc – from Istanbul in Turkey, reported his success using AnalysIR to easily record the signal timings for his AC unit and sent us the details along with some nice photos. After testing the validity of the recorded signals using an Arduino, he then set about loading the signals onto his Samsung smart phone (models S4, s4 mini, S5 and more supported). This was helped by installing the free ‘Samsung IR – Universal Remote‘ app onto his phone via Google Play.
A while ago we came across a website on infrared remote controls which suggested a simple way to view IR signals using an Oscilloscope. The idea is to use a standard IR Led mounted into a BNC/RCA plug using a spare channel making an Oscilloscope infrared receiver. So we set about ordering the connectors, which arrived in the post today. Another way of looking at this device is as a ‘poor-mans’ IR receiver, but if you have an Oscilloscope to plug it into then maybe you are not so poor after all.
Recently we have been helping several members on the Arduino forum to record and playback their remote control signals from their Air Conditioners. These signals are typically much longer than those of TVs or common media devices. The 2 most popular libraries for Arduino, IRremote & IRlib are excellent, but have some limitations which we have covered in a previous post. In this post we address one particular issue that is proving challenging to users.