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Great projects guys! Tru, what size 'box' do you need to house this? In other words, what are the sizes of everything you need to fit inside?
Most certainly. What if it weren't a box, but a tube or two? Any chance?
Been hitting the drawing board pretty hard. Its hard to not have the feature set snowball when using a micro controller.My Design so far:3.7 volt single Li-On cell powered2x8 back-lit displayVariable voltage using a DC-DC booster 3.80v - 6.2v at 0.05v steps.3 button interface.display shows Volts, Amps, Watts, Resistance & battery SOC on demand.device senses Shorted Atty, Open Attyuser can change voltage, display contrast, back light on/off via the 3 button interface.user can change if display is on or off during vaping.measures amp, volts, watts under load.Low battery warning via display.Over current warning via display.USB charging.Initial schematic finished.Initial Software flow chart finished.Initial Software psedo-code finished. (I forge out the psedo-code so I have a template used as a blueprint for multiple micro - controller platforms. All my past experience is with Microchip 8bit controllers. May go with one of their 16bit units or switch to ATMELCreative juices flowing for a possible tube-mode solution as enclosure, without being overly bulky.Parts on order.
Perhaps I should keep my processor powered all the time and make it go into sleep mode when not needed. Shutting pwr completely off and on doesn't seem to be the way to go.Funny though, when it was on a bread board, it worked consistently well every time. From complete power down to powering up.
Yeah Craig is bang on with all the theory and best practice(s). Everything mentioned I have been heard from other digital engineers. (one of them worked on space-shuttle, B2 stealth, and various spy satellites).I planing a using 3v LDO reg with an ultra-low quiescent, as well and all 3v components:Digi-pots, sensors, & MCUSince I am using only a 3.7 volt battery, I don't have much overhead to play with. Hopefully the battery voltage won't drop off too much under load. I found some pretty good 3v and Adjustable LDO's than can source up to 500mA. I have calculated that about 300mA would be highest possible amp demand for my particular setup. (on the digital side) and typical less than 100mA during normal operation and just micro amps when sleeping. It will be interesting to see what the actual amp draw is compared to the calculated.Some of the LDO's were in the SOIC8 package, which I find pretty easy to deal with. I have some SOIC8 to bread board adapters that I use during the prototyping phase and SOIC8 is NOT too high on the P.I.A. scale for soldering.Will post some pics soon.
I think the size of the 8 x 2 LCD display will fit nicely in a small box. The results are tight. No room for a space between values.Note: have to look at my math code on rounding the numbers. the power calc is slightly off. Should have been 6.71w. The resistor, amps and voltage are dead on. Compared against my MultiMeter.
Being you are using a single battery, wouldn't it be possible to for-go the regulator and power just from the battery? I read that somewhere on a site.I need 5v so I couldn't go that route.
That half volt margin would not be enough for a single ICR 18650. I would have to run two ICR 18650s in parallel or one IMR 18650 to get battery DC resistance down low enough. I'd also have to use a 2.7V detector for over-discharge protection.
Seem like the with an LDO, if the Vin is from a battery, the Vout is not really going to have hardly any ripple. Not like a transformed / rectified AC source.
...You either need to run two in parallel, or use a CGR18650CH which is Panasonic's high drain 18650. It has half the internal impedance and almost double the drain limit. It comes at a cost in charge capacity, 2150mAh peak for the CGR18650CH versus 3100mAh peak for the NCR18650A. ...
I had noticed my MCU regulator dipping when I fired up the OKR-T/6 that I had mounted on the same PCB. I did what Craig suggested by separating the ground plane for the DC-Conv and added the extra de-coupler for VCC to mcu but it didn't help.I removed the OKT-T/6 off the PCB and NO dip in regulator voltage at all... Rock Solid output now.When I cram it all into an enclosure I will keep the Converter away from the MCU circuitry and leave the converter separate.
That's a good way to handle it.If you use a 1uF cap and increase resistance to 2.2k and 6.8k, the filter will work exactly the same and you'll get less current draw.
Been playing around with an Atmel's ATMega328 Processor in 28 pin DIP package. Chip came pre-loaded with the Arduino Optiboot (Uno 16MHz) Bootloader. Installed it on a Programmer breadboard I made which I plan to also use for loading my own bootloader on future chips.Chip worked fine and loaded simple sketches on it several times. The second day, I loaded a new sketch and received an error: Avrdude: stk500_getsync(); Not in sync; resp=0x00. Did some googling and found several people having similar issues. Seems to be communication problems. Tried every possible means unsuccessfully to get it working.Finally this morning with changing devices to write to and com ports as I did yesterday, it worked . Must be buggy Arduino software because the settings are the original settings.