Some time ago I have purchased online carbon dioxide (CO2) sensor module MH-Z19b. It's a cheap and very simple sensor with the UART interface allowing concentration measurement in the range up to 5000ppm.
While working on a CO2 sensor [/2019/06/10/carbon-dioxide-sensor-mh-z19b-part-1/] I needed to manage the device without any human interface or additional connectors. Fortunately, the ESP8266 devices include the WiFi interface and it was obvious step to use it for device management.
A few days ago I have taken part in the discussion on Reddit about displaying JPEG image on black and white e-ink screens attached to the ESP8266 MCU. The original poster asked how to use external service to convert RGB image into dithered black and white one.
> Buy the CH340G programmer for ESP8266/ESP32 > [https://www.tindie.com/products/thinkingthing/usb-programmer-for-esp8266esp32/] > online
It's quite some time since the last update about my awesome FIDO2 Authenticator project [/category/fido2/]. The project did not stop, no. The latest challenging point was the idea that I should not use the external biometric scanner with UART interface but make a built-in one. So, I have ordered a few more biometric scanner modules and, unfortunately, it took several weeks to deliver.
After some disruption on hardware design, I have returned to writing driver for the FPC1020 fingerprint scanner [/2019/12/03/fpc1020-fingerprint-scanner/]. It's sad, but as I don't have complete documentation the process takes a significant amount of time and a lot of effort. To speed up the evaluation I started to write relevant code using C++ and Arduino Framework.
Part 1 - Hardware design [/2019/06/10/carbon-dioxide-sensor-mh-z19b-part-1/] Prototype projects do not require complex software and I am using the Arduino framework because it has plenty of useful libraries for all possible device types. For compiling the project I am using PlatformIO framework.
Recently I have purchased one more carbon dioxide sensor module - CJMCU-811. The module is built on a chip CCS811 by company ams.
Having two different CO2 sensors it makes sense to put them together and compare reading over some period of time.
It's quite a long time since the last update, but the summertime asks you to spend more time outside and I could not resist this call. Nevertheless, here's the small project I made.
About one year ago I have purchased a widely available fingerprint identification module with UART interface. You can find this module almost everywhere for quite a decent price. However, the information about how to use it with Arduino is not that easy to find. I am interested to use it with the URU Card [/2020/06/29/uru-card-arduino-fido2-authenticator/] device so I took some time to play with it.
> Buy the CH340G programmer for ESP8266/ESP32 > [https://www.tindie.com/products/thinkingthing/usb-programmer-for-esp8266esp32/] > online
Recently I was exploring the differences between IBUS and SBUS protocols used in remote controls. The IBUS protocol appears to be a very simple half-duplex UART operating on speed 115200 baud. Packets of a fixed size, simple checksum calculation... Wait a second. What if we take the dirt-cheap ESP01 module, program it as the receiver and operate it with the smartphone? In just half an hour the minimal prototype was built.