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How can an Arduino be used to show open/closed trading times of stock exchanges within a Time zone clock display?

I'm making a clock display for my wall, with 3 clocks showing the times in NYC, London & Hong Kong. I want to use them partially to monitor each cities' stock exchange (opening & closing trading hours). Is there a way to integrate an Arduino to control two LEDs (1 green 1 red) and turn green for trading hours and Red for closed in each clock? 1 Arduino per clock I assuming. 


I have experience with Ardunios and this project will include a Arduino (obviously) breadboard with jumper leads, xbees, LEDs, 9v (a set of all these things per clock I'm guessing), but this is beyond my knowledge base, and wanted to seek the help of those who know more.

lf battery life is going to be an issue (always illuminating an LED), 1 green light for open trading could also be used to save electricity.  How can I create an trading hours database, reference GMT time and a script which uses all this data to make a true/false value for an LED to show the current open/closed status?
In short how can I bring the project to life? Is it even possible?
I would be very grateful for any help. Thanks.

janw6 years ago
For timekeeping I would use my favorite DS1307 I2C RTC and let him run in GMT. Then the arduino can calculate the local time from that base. The DS1307 also knows the date dan the day of the week so on days where there is no trading the leds won't go green.

for your dislpay you can also us I2C protocol with these kind of displays. This way you only need 2 pins for the clock and the 3 displays. if you then use bi-color leds, you can build the whole project with only 8 pins on your arduino.

good luck!
maewert6 years ago

Bicolor 7 segment LED displays can be found on the internet. Here is one that is single digit only:
http://www.betlux.com/led/0.80-inch-single-seven-segment-led-display--bi-color-BL-S80A-11XX,BL-S80B-11XX.htm

Of course you can use four of them :-)

Look around and you should be able to find a 4 digit or a 3 1/2 digit version. (They are called 3 1/2 since the first digit is usually only 0 or 1 assuming a 12 hour clock)

To get the time you can use a real time clock or even a GPS module.
Others have posted instructables that simply use the Arduino's 16 MHz clock to keep time (although I don't know how accurate this method is over time).

Battery life would have to be calculated. You may need a solar cell or AC power. If you are doing this to the minute your code could place the arduino into a pow power sleep mode that is awakened based on a counter that is set up to wake every minute (assuming you are using a separate LED driver module and do not need to use the Arduino to scan the 7 segment displays.)

Lots of options here.
Best Wishes.