Member Since: October 17, 2012

Country: United States

  • The speaker accessory would also be a good item to carry so customers don’t have to go to another site to get all the pieces they want. (Which would probably lose a sale here if the customer has to go elsewhere which has all the pieces they want.)

  • Charlieplexing wouldn’t work well with this because of the common anode configuration. A grid matrix, yes. But not charlieplexing.

  • To those playing at home, the APA102 LED strips are the same thing that AdaFruit sells as DotStars. So if you are building a project with SparkFun parts based on a published DotStar design, you won’t have to split your parts order for the LED strips now.

    The high PWM frequency of the APA102 makes them much more suitable for persistence of vision (PoV) projects than WS2812 (NeoPixel) based LEDs.

    Thanx for the 2nd source, SparkFun! :-D

    Also, I’d be tempted to argue if the footprint of that bargraph is compact or not. It is (nearly) as compact as it can be based on the physical size of the display. It doesn’t take much more space than the LEDs. But the way the legs are staggered along the length, one can’t get away with hanging it off the edge of a board unless one creates a separate carrier board that pulls all the connections down to a single grid of pins at one end. (Hmmm… sounds like a quick project to design and throw up on OSHPark…)

  • Too bad the chronodot doesn’t use the DS3232SN… That is I2C like the DS3231SN, but includes NV SRAM (but only 236 bytes instead of the 256 bytes of the DS3234).

    But, maybe that is an opportunity for SparkFun. A refresh of the DeadOn RTC:

    • Upgrade the current version to the …SN variant and add the RESET and 32khz breakout pins.
    • Make a new breakout board for an I2C DeadOn using the DS3232SN.

    That would give customers the option of I2C or SPI without loosing the accuracy and existence of on-board memory.

    Also, Adafruit’s breakout and feather wing board only uses the …S variant, not the …SN variant. The …S variant isn’t rated for accuracy below freezing.

  • What I often use the SQW pin for is I set it as 1Hz (1PPS) and attach it as an interrupt. Then on the falling edge I set a flag. I then only regularly read the time if the flag is set. Yes, I can’t use alarms with this technique, but I only have to spend the clock cycles to communicate and parse the response of the RTC once a second, instead of on every loop of my code.

  • There are a couple minor differences (or major if your project depends on them…) in addition to I2C vs SPI:

    • The chronodot has the RESET and 32kHz pins broken out which this doesn’t.
    • The chronodot uses the …SN variant which is tested/qualified to keep accuracy below freezing (zero celsius). Specifically, the …SN variant is rated -40°C to +85°C, but the …S variant is only rated 0°C to +70°C.
    • The DS3231N on the chronodot doesn’t have battery backed RAM, but this DS3234 has 256 bytes of NV SRAM.
  • No, not by itself.

    Because the DST rules are different in different countries (and sometimes different within portions of the same country) and subject the the whims of what ever politicians are in charge, it would make no sense to hard-code the rulesets into silicon. There is a DST library available for Arduino (I forget the site and don’t have time to Google it for you), or you can simply code in the rules for the target location where you plan to deploy your clock.

  • Why are you telling people to tie the SQW pin (which is an output) to GND? Granted this is an open drain output so grounding it shouldn’t hurt it. Here is what the datasheet says about the pin:

    Active-Low Interrupt or Square-Wave Output. This open-drain pin requires an external pullup resistor. It can be left open if not used.

    If you aren’t using it, just leave it unconnected. It’s a bad habit to tie unused outputs to ground. It’s the unused inputs that should be tied either to ground or VCC.

  • The Chronodot uses the DS3231N (this is the industrial version that is tested to work below freezing). The versions that I’ve used have solder locations for I2C pullup resistors, but leave it up to you to decide if you need them or not. I think you can get the Chronodot over at EvilMadScientist and/or AdaFruit. Maybe other places. Creative searching might find DS3231 based breakouts less expensive than the chronodot, but you won’t get the cute round PWB. ;-)

    Watch out, though. The DS3231 doesn’t have NVRAM, so if you plan on using the storage (for example, storing daylight savings time rules/settings) then you are out of luck.

  • I don’t know how severe your visual impairment is, but you may want to look into trying out a magnifier visor. Not the most fashion-forward accessory, but really helps to see those little details. Because it is a visor, it should work with most glasses (but I can’t guarantee how compatible it is with your prescription). I have one that has an integrated LED lamp that helps to remove the shadow that my big, fat head would otherwise cast over my workpiece.

    Here is an Amazon search so you can get an idea of the options out there. In fact, this is the one that I have. It is kinda cheaply made, I have to constantly re-tighten the swivel points between the visor and the head band. And the slide switch inside the lamp is intermittent (a firm tap usually gets full brightness back). But what do you want for less than $10USD?