Reading DHT22 and Light sensor data using NodeMCU dev board

Experimented with reading DHT22 amd Light sensor modules using NodeMCU ESP12E development board. Main problem I had that timer did not work on old firmware, had to update it ( read previous post ). Other that that all went fine and could read data.One strange thing is that I am getting temperature a little bit higher than actual. Not sure why is that, maybe because board is powered by 3.3v and not 5v. Will have to find out that later.Code:if not tmr.alarm(0, 5000, tmr.ALARM_AUTO , function() print("Starting to read data:")…

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tmr.alarm not working on ESP12E 0.9.5 firmware

Tested that this sample was not working on dev board:if not tmr.alarm(0, 5000, tmr.ALARM_SINGLE, function() print("hey there") end) then print("whoopsie") endChecked firmware version (connected to ESPlorer and pressed reset):ESP12E default NodeMCU 0.9.5 build 20150318  powered by Lua 5.1.4Decided to update firmware. Found here that only 9.6 is available precompiled, later ones have to be costum built. Downloaded 9.6 files and uploaded them using ESP8266Flasher.exeChecked firmware version then:NodeMCU 0.9.6 build 20150704  powered by Lua 5.1.4And tested this code sample:if not tmr.alarm(0, 5000, tmr.ALARM_SINGLE, function() print("hey there") end) then print("whoopsie") endIt worked.

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How to use Arduino IDE to program NodeMCU

1. Install the Arduino IDE from download section of website 2. Run Arduino IDE's arduino.exe3. Arduino IDE >> File >> Preferences (Shourtcut is CTRL + COMMA)>> Settings tab >> on Additional Board Manager URL side type this >> and click ok. json object will bring necessary drivers for NodeMCU from the website to our Arduino IDE.4. Arduino IDE >> Tools >> Board >> Boards Manager... >> Type = Contributed >> click on install (Or, search ESP8266 from the search bar)5. Arduino IDE >> Tools >> Board >> NodeMCU 1.0 (ESP-12E…

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Repairing ZX Spectrum Kempston joystick

As recently I started tinkering with ZX Spectrum hardware, tested one old joystick I had. Up and right positions did not work during the games. Tested port reading with one simple program:10 LET x=IN 3120 PRINT X30 GOTO 10There was no reading in up and right position.I took apart joystick case and tested connection between PCB and plug - there was no connection for up and right wires.So, just took now DB9 female connector and soldered it instead of an old one that I have just cut away. 

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Fixing ZX Spectrum+ 48K (s/n S01-135100) video problems

So, this ZX spectrum was alive, but during testing with some games (for example game "Breakthrough"), I noticed strange video glitch in upper screen part:My guess was it is not video RAM related, but probably RF module fault. First decided to change all electrolytic caps on the board and see if it helps - it did not. Picture was the same.Then decided to check RF module - remove it and re solder all joints.After putting it back I did a check with the same game. It helped a bit, but…

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Another ZX Spectrum 48K

Maybe I got carried away.. but here is another non working rubber keyboard ZX Spectrum I got (s/n D01-257600).Its interesting regarding those serial numbers, some are 01 some D01. I really would like to know what do they mean, if they mean anything ? Found one site that has list of some serial numbers and has a form to submit more. Probably later I will submit them serial number of my ZX Spectrum machines. But now, back to this one.. On the outside it has some bruises and scratches, also…

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Repairing ZX Spectrum+ 48K

Another was ZX Spectrum+ 48K (s/n S01-135100). After turning it on could not see clear image (sorry did not take image of that picture). When I disassembled this device I found that it already had some changes, lower RAM chips were not original, it had some jumper wires soldered on PCB, transistor TR4 seemed like already replaced (at least someone did some soldering with it). Expecting the worst I started to check voltages (using this guide) and noticed that 12V is missing on lower RAM chips. When checked transistors TR5 and TR4 found that…

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Repairing and upgrading ZX Spectrum 16K

Going back into retro computing. Recently got little bit nostalgic and purchased two used non working ZX Spectrum machines. One was 16K, SN 001-201230.Tested some voltages using this guide and it seemed like everything is more ore less normal. Plugged it to TV antenna, tuned to channel 35, turned it on and as expected it didn't work. As usual biggest suspects were 4116 lower RAM chips:I had two options, first was to cut those IC`s out and desolder leads that were left using regular soldering iron. But doing that I would…

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