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Saturday, April 8, 2023

NTP clock on 4 OLED displays

    I wanted to created a special clock as a vintage clock with VFD display, so I realised ca easiest way is to use an i2c expander as TCA9584A chip/module.

   I used info from article Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino

   I used this schematic:
and I tested Santos's sketch:

   For a real NTP clock with DST selector (winter/summer time) I used this schematic and NTP_clock_TCA9548A_4OLEDs_1.ino sketch:
so combined schematic
   For DST=1 (summer time):
and for DST=0 (winter time)
  I uploaded 2 movies:

After than I added the feature to see clock as VFD display, as in article 
so you find how clock is in this video:
NTP clock with 7-segment numbers on 4 OLED displays (2)
   I moved the project from breafboard to a classical PCB (sandwich) with 2 PCBs):
so you can see the 2 other videos:


Sunday, July 10, 2022

X9C103 digital potentiometer with EEPROM stored initial value

      I received few X9C103 digital potentiometer modules with 10kΩ and I need to prepare it for tests:

   I used this schematic:
where in A0 is voltage fron wiper of potentiometer (as a resistive divider for 5V power supply) and also I read 5V voltage in A0 (to check if is 1023).

   In the previous tests with a remote contributor X9C103 potentiometer not store value in NVM, so I used an oscilloscope to saw the signals... the signals are ok, but chip not store the value in NVM (non-volatile memory):
so I used EEPROM memory from Arduino Nano board (ATmega328P chip).
   Last sketch is pot_X9C103_1_1.ino. and in this sketch it used LapX9C10X library (also X9C103 chip "not want" to store the value using writeNVM() command from this library).
   I upload the X9C103 digital potentiometer with EEPROM stored initial value where you can see how sistem works:

Bibliography: article in romanian languageTeste cu potentiometrul digital X9C103 (10kΩ) !

Thursday, June 23, 2022

Railway Crossing Multi Track Two Way

    This article is based on the article with same name and Railway Crossing Part 4: Putting it all Together article.

   My tests included few models until at last version with sounds (warnings) and other count method for trains, but main structures are same:

Railway_Crossing_1 (just added tip and free lights), sketch: us_barriers_rudysarduinoprojects_1b.ino

Railway_Crossing_2 (added sounds using Mike Osborn MKO tips),sketch: bell_and_button_servo_4
Railway_Crossing_3 (added sounds and test different count methods: original with few updates or big changes)
with 3 sketches 
   For last sketch, I uploaded this videos:
Railway Crossing with lights and sounds for Multi Track Two Way
   If no train between IR sensors, barriers (gates) are open:
but at least a train is between sensors, barriers (gates) are closed:

   I changed the sketch for remove sound after gate is open (us_barriers_2b_2)
as Jedidiah Sawyer wanted. 
   Last change of the sketch is to have also fading light as in 2nd Avenue Railroad Crossing, Clanton, AL

so, last sketch is us_barriers_2b_3
and a short video made by Jedidiah Sawyer:

   The variable for change the fade effects are:
and the fade for LED3 is
so, LED3 is off (brightness = 0), than after 200ms (variable time_to_stop) brightness increased at 1 (variable fadeAmount), than after 2 ms (variable fade_delay) brightness is 2, after more 2ms brightness is 4, etc, until brightness is 255 (maximum = 100%) .. is a pause (time_to_stop = 200ms) and after that brightness decrease with 1 at every 2ms until 0... 
Leds for blink effect (LED1 and LED2) are same period as fadding leds (LED3and LED4):, you can change the values as you want,...