Planned build – and a few of questions

[dwbconz]

I’ve ordered a kit and shipping times mean I should be receiving it in a couple of weeks.

I’ve not done any decently involved physical electronics projects before, but I’ve got a few years programming experience, as well as back-end web design and systems/network exposure. All these things will be needed for my plans.

I’ve looked over the schematic and briefly looked through the code, I’ve got a few queries:

• How would I change the brightness of the digits – is this a code change for a PWM output modification or can I change a resistor? I’d prefer to have this changeable by code, because it means I can have multiple brightness settings, or I may look at getting a light dependent resistor connected to the remaining free analog input pin to have an adaptive brightness based on ambient light conditions in the room.
• What are the values of the four resistors connected to the various LED’s on the board? I’ll also look at changing these out for higher ohms to dim the LED’s while they’re on.
• I’ve seen it said in the forums multiple times that a 12V power supply -should- be ok, but to monitor the temperature of the voltage regulator. Is there a different voltage regulator I may be able to get that would better handle that? I suspect if there was one, it probably wouldn’t fit the holes in the PCB.

So, those questions out of the way, here’s my plans, laid out in full.

I intend to add day awareness to the alarm clock, so I can set my alarm Mon-Fri only.

I have an existing arduino which I once used for an LED PoV toy. It’s been sitting idle since then, so I thought I’d use it to expand on the functions of the defusable alarm clock.

My arduino will control a separate circuit, which will have about 5m of LED strips around my room, hidden behind various items of furniture. Using this, I will be able to fade in and fade out these LED’s; one of the intents of this is as a night light so when I wake up in the middle of the night I can have some dim soft light around the room instead of direct lamps. The other intent of this is so that when the alarm turns on, it will also send a signal to the arduino controlling these lights, which will over the period of a few minutes bring them up to full brightness.

I want to have web based control of the alarm clock functions, so that will be implemented on a web server running on my other arduino. I intend to establish a serial comms channel between the two systems for control, and I’ll write in the controls to the defusable alarm clock to adjust variables appropriately when certain commands are received.
Controls I intend to add include:

• Basic password authentication (don’t want people at home screwing with this, and screwing with my sleep)
• Showing the current time
• Setting the time (I’ll also set my PC at home to have a scheduled task every hour to send a time update from its on board clock, which is synced with NTP. This will mean the alarm clock stays accurate without my intervention. Will investigate the possibility of having the alarm clock automatically get NTP updates on the hour via the serial communications channel with the Ethernet connected arduino.)
• Setting the alarm time, days, and beep pattern
• Testing the alarm beep pattern
• Turning on/off the lights
• If possible, setting the dimmer level of the LED digits

I’m probably also going to end up setting it so the only way I can disable the alarm is through the web interface, and just not use the defuse function; I’ll leave the wires all connected for decorative purposes though. Haven’t yet decided what case I’m going to mount this all in.

[Michael]

You can’t change the brightness in software. The LEDs are not driven by PWM. They are driven by a 7-segment driver chip.

You can make them dimmer by changing the 8 150 ohm resistors under the display to larger values. For example, 220 ohms, or higher. Just try some things, I think.

You can power the clock from 12V, but the regulator will get warmer. Not too warm, just warmer. Any regulator that takes in 12V input and ouputs 5V needs to dissipate the power as heat, so all regulators should output the same amount of heat.

[dwbconz]

OK, well that at least gives me a point to work from for the brightness settings. I’m still going to try to control that through code, I think it’s doable if I use the free analog pin as the base input for 8x transistors to replace the 8x resistors that are there, though I’ll probably have to add a decoupling capacitor to each base to ensure they get consistent signal across them all.

[Michael]

Ok, best of luck. I still don’t see how you can change the brightness. Analog pins are analog input, not analog output.

[GreggGraham]

@dwbconz wrote:

I’ve ordered a kit and shipping times mean I should be receiving it in a couple of weeks.

I’ve not done any decently involved physical electronics projects before, but I’ve got a few years programming experience, as well as back-end web design and systems/network exposure. All these things will be needed for my plans.

I’ve looked over the schematic and briefly looked through the code, I’ve got a few queries:

• How would I change the brightness of the digits – is this a code change for a PWM output modification or can I change a resistor? I’d prefer to have this changeable by code, because it means I can have multiple brightness settings, or I may look at getting a light dependent resistor connected to the remaining free analog input pin to have an adaptive brightness based on ambient light conditions in the room.
• What are the values of the four resistors connected to the various LED’s on the board? I’ll also look at changing these out for higher ohms to dim the LED’s while they’re on.
• I’ve seen it said in the forums multiple times that a 12V power supply -should- be ok, but to monitor the temperature of the voltage regulator. Is there a different voltage regulator I may be able to get that would better handle that? I suspect if there was one, it probably wouldn’t fit the holes in the PCB.

So, those questions out of the way, here’s my plans, laid out in full.

I intend to add day awareness to the alarm clock, so I can set my alarm Mon-Fri only.

I have an existing arduino which I once used for an LED PoV toy. It’s been sitting idle since then, so I thought I’d use it to expand on the functions of the defusable alarm clock.

My arduino will control a separate circuit, which will have about 5m of led lights around my room, hidden behind various items of furniture. Using this, I will be able to fade in and fade out these LED’s; one of the intents of this is as a night light so when I wake up in the middle of the night I can have some dim soft light around the room instead of direct lamps. The other intent of this is so that when the alarm turns on, it will also send a signal to the arduino controlling these lights, which will over the period of a few minutes bring them up to full brightness.

I want to have web based control of the alarm clock functions, so that will be implemented on a web server running on my other arduino. I intend to establish a serial comms channel between the two systems for control, and I’ll write in the controls to the defusable alarm clock to adjust variables appropriately when certain commands are received.
Controls I intend to add include:

• Basic password authentication (don’t want people at home screwing with this, and screwing with my sleep)
• Showing the current time
• Setting the time (I’ll also set my PC at home to have a scheduled task every hour to send a time update from its on board clock, which is synced with NTP. This will mean the alarm clock stays accurate without my intervention. Will investigate the possibility of having the alarm clock automatically get NTP updates on the hour via the serial communications channel with the Ethernet connected arduino.)
• Setting the alarm time, days, and beep pattern
• Testing the alarm beep pattern
• Turning on/off the lights
• If possible, setting the dimmer level of the LED digits

I’m probably also going to end up setting it so the only way I can disable the alarm is through the web interface, and just not use the defuse function; I’ll leave the wires all connected for decorative purposes though. Haven’t yet decided what case I’m going to mount this all in.

SOunds like decent project.. Were you to accomplish it or still working? I would love to work on similar project so please reply

[Author]

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