Go Down

Topic: Single digit, Seven segment Numitron program and pcb design needed. (Read 19121 times) previous topic - next topic

Daddyfredregill

The 1.27mm and .65mm piches. Which chips are those for?

Daddyfredregill

So the RTC I got looks like it is the 1.27mm pitch but I think both. Sot23-5 chips(booster and charger) are .95mm. I cant even find a .65mm option chip for either of those two.

wvmarle

SOT23-5 must have breakout boards available as well. All those package types do.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

Yeah i found some on ebay. Will tue .95mm pitch impact the pcb design alot?

wvmarle

Not at all, as I've simply selected the SOT-23-5 package in KiCAD. It knows how it looks like, and where the pads go, that's all in the libraries. For most packages I don't really know the actual dimensions, just make sure to select the correct package.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

Got all my parts in except my breakout boards. They are coming from China so hopefully they get here.

wvmarle

Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

Have you ever had any dealings with buying breakout boards and such on Ebay from China sellers? All the ones that I purchased had really high ratings. I am assuming they take so long because it is overseas.

wvmarle

I never buy from E-bay, I just go straight to Taobao, they're the cheapest. Usually shipping within 1-2 days and then 1-7 days for it to get to me depending on the method. Sometimes I've received things the next day, incredibly fast :-) It helps of course that all those electronics are from Shenzhen which is just across the border.

I've used element14 as well, great selection and often good prices, but shipping was remarkably slow - it had to come from Singapore, took them several days (it's just 4 hours on the plane so shouldn't be that long).
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

Finally got all my parts. I will be soldering up the dip adapter chips and building the circuit in the next month or so.

wvmarle

Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

I have gotten all my SMD to DIP board ready. I have a few questions about the build of the circuit.

1. There is a line in the charging/boost part that says "switch", does that go to either SW2 or SW1 or does it need to go the pin 3 before SW1 or after SW1?

2. The spots labeled VCC is my +incoming power, I assume it is my boosted power out of the booster IC(5V)?

3. On the ATTINY441 I am just double checking on how to hook the display up, so pin 13_a on the arduino, that gets connected to a_15 on the display? And so on?

4. The four resistors at the bottom of the diagram, the one that says miso, does that get connected before SW2? I am assuming the rest of the resistors go directly to their labeled pins on the arduino?

5. The program header do those pins go before the pull down/up resistors in the previous question? Example- do I connect the miso pin on the J1 header in front of the miso resistor?

6. How will I be able to program the the arduio with those six pins? I do have a arduino Uno R3 available if that helps. I currently have no program to even run on it. Not really sure where to start on that

7. Any more tips you have on how to build this circuit? Any way to test certain sections before hooking it all up? Should I try to just test the power circuit?

Thanks for all you have done so far. I really appreciate it.

wvmarle

Hi,

Good to hear that!
It's a long time, I almost forgot about this :) Really had to look at the schematics on how everything was planned.

I have gotten all my SMD to DIP board ready. I have a few questions about the build of the circuit.

1. There is a line in the charging/boost part that says "switch", does that go to either SW2 or SW1 or does it need to go the pin 3 before SW1 or after SW1?
Yes, that goes to pin PB1 (pin 3). This pin is multiplexed: used both as switch and to sense the voltage. The trick is that when used as switch it's pulled to GND so ADC reads 0, otherwise it's a higher value (depending on actual battery charge level).

Quote
2. The spots labeled VCC is my +incoming power, I assume it is my boosted power out of the booster IC(5V)?
Indeed.

Quote
3. On the ATTINY441 I am just double checking on how to hook the display up, so pin 13_a on the arduino, that gets connected to a_15 on the display? And so on?
Indeed - follow the labels (in black).
I've been using labels a lot in this schematic - not always the easiest to follow when wiring by hand indeed, but makes the schematic a lot easier to deal with. Less wires there.

Quote
4. The four resistors at the bottom of the diagram, the one that says miso, does that get connected before SW2? I am assuming the rest of the resistors go directly to their labeled pins on the arduino?
Indeed - that's a bunch of pull-up resistors. Directly to the pins. Come to think of it, MISO doesn't need a pull-up, the switch does but we can use the internal one. No need for that 10k resistor.

Quote
5. The program header do those pins go before the pull down/up resistors in the previous question? Example- do I connect the miso pin on the J1 header in front of the miso resistor?
Doesn't matter. As long as the header pin is directly connected to the processor pin.

Quote
6. How will I be able to program the the arduio with those six pins? I do have a arduino Uno R3 available if that helps. I currently have no program to even run on it. Not really sure where to start on that
Quote
You probably have a script called "Arduino as ISP" in the IDE. That one you have to install on the Arduino; connect the wires as per instruction in the sketch (use "old style wiring"), and when done connect a 10µF cap (mind polarity) between the Arduino's reset and GND pins to prevent it from resetting.

Quote
7. Any more tips you have on how to build this circuit? Any way to test certain sections before hooking it all up? Should I try to just test the power circuit?
You can (and should) test the power and charging circuits separately. That's one part of the build. For testing you don't need to use it per se, as long as the rest of the project has 5V power it's fine.

It's actually probably easiest if you build the processor + RTC + Numitron on a breadboard first, and get that fully working. Make it display the time and date upon button press, that kind of things.

Wouter.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Daddyfredregill

Ok, so MISO resistor does not need to be there anymore? Also on the numitron schematic is says to "Buss all commons to +lamp supply, and ground return is through decoder". Don't the output pins on the arduino have a +5v on them? Would that not cause two power sources at once? So commons would have +5v and the arduino would be putting out +5v. I am missing something I think

wvmarle

If the Arduino pin is set to +5V, and the common anodes to +5V, the element will be off. Both sides at the same potential so no current. Arduino pin to GND, current flows, element is on.

Which makes me wonder why there are no current limiting resistors there... numitron displays don't need that, right?
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Go Up