Swapping out a NiMh for a LiPo?

[eccerr0r]

Re: Swapping out a NiMh for a LiPo?

It'll be full again in no time!

[stj]

Re: Swapping out a NiMh for a LiPo?

just change up the mcu for a bigger flash one with the same pinout.

[eccerr0r]

Re: Swapping out a NiMh for a LiPo?

microcontroller flash is always full.
It's gotten so bad that I end up making all textual output as terse as possible to save all those bytes of flash I can...
One of the projects I was working on was a power supply, it too was 97% full on 4K of flash. I ripped out so much of the serial interface and relied only on LCD and front panel control.
1200 lines of .c code with comments... but it's the libc library functions that killed flash memory. The AVR I was using didn't have a hardware multiplier so it had to link in the software multiplier...

... and that RAM I wasted on the CLI buffer... had to chop that down too... I think I had it down to 16 characters command "line" so I could allocate more RAM for the PID controller state.

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

I was actually able to get rid of the portion of the code that relied on the EEProm being 0 or -1 by tweaking things a little bit...

The SoftwareSerial library takes almost 50% of the entire code memory on the ATTINY, but now, when you burn the code to the chip, you simply connect it to a serial interface, and then you can set the time if it's not already set and you can tell it to start a refresh cycle the next time 8 AM happens.

This code takes 97% of the memory available for code storage.

Here is the sketch if anyone is interested:

#include <Arduino.h>
#include <TimeLib.h>
#include <DS3232RTC.h>
#include <EEPROM.h>
#include <BlockNot.h>
#include <SoftwareSerial.h>

#define Rx 3
#define Tx 1
#define RELAY 4

SoftwareSerial serial(Rx,Tx);
BlockNot checkTimer(300, SECONDS); //Five Minutes

long THREE_HOURS = 10800;
long SIX_WEEKS = 3628800;

int NEXT_REFRESH = 0;

time_t rightNow;


void printDigits(int digits){
  serial.print(":");
  if(digits < 10)
    serial.print('0');
  serial.print(digits);
}

void digitalClockDisplay(){
  serial.print(hour());
  printDigits(minute());
  printDigits(second());
  serial.print(" ");
  serial.print(day());
  serial.print(" ");
  serial.print(month());
  serial.print(" ");
  serial.print(year());
  serial.println();
}

void powerOFF() { digitalWrite(RELAY, LOW); }

void powerON() { digitalWrite(RELAY, HIGH); }

void flash() {
  for(int x=0; x<4; x++) {
    powerON();
    delay(750);
    powerOFF();
    delay(500);
  }
}

void writeEE(int address, long value){
  byte four = (value & 0xFF);
  byte three = ((value >> 8) & 0xFF);
  byte two = ((value >> 16) & 0xFF);
  byte one = ((value >> 24) & 0xFF);
  EEPROM.write((address * 4), four);
  EEPROM.write((address * 4) + 1, three);
  EEPROM.write((address * 4) + 2, two);
  EEPROM.write((address * 4) + 3, one);
}

long readEE(int address){
  long four = EEPROM.read((address * 4));
  long three = EEPROM.read((address * 4) + 1);
  long two =  EEPROM.read((address * 4) + 2);
  long one =  EEPROM.read((address * 4) + 3);
  return ((four << 0) & 0xFF) + ((three << 8) & 0xFFFF) + ((two << 16) & 0xFFFFFF) + ((one << 24) & 0xFFFFFFFF);
}

void doRefresh() {
  powerOFF();
  static long now;
  static BlockNot refreshTimer(60, SECONDS);
  now = (long) rightNow;
  long startTime = now;
  long nextRefresh = now + (SIX_WEEKS - THREE_HOURS);
  writeEE(NEXT_REFRESH,nextRefresh);
  bool keepRunning = (now - startTime) < THREE_HOURS;
  while(keepRunning) {
    if (refreshTimer.TRIGGERED) {
      now = (long) RTC.get();
      keepRunning = (now - startTime) < THREE_HOURS;
      powerOFF();
    }
  }
  powerON();
}

void processSerial() {
  String in = serial.readString();
  String first = in.substring(0,1);
  if (first.equals("?")) {
    serial.println(F("TXXXXXX to set time, use 'date +T%s' to get time\nG - shows the time from the RTC\nF - Sets next refresh to happen when the hour is 8 AM"));
  }
  else if(first.equals("T")) {
    long num = in.substring(1).toInt();
    time_t t = num + 2;
    if (t > 100) {
      RTC.set(t);  // set the RTC and the system time to the received value
      setTime(t);
      adjustTime(-25200);
      serial.println(F("Time Set!"));
    }
  }
  else if(first.equals("G")) {
    digitalClockDisplay();
  }
  else if(first.equals("F")) {
    long now = (long) RTC.get();
    writeEE(NEXT_REFRESH,now);
    serial.println(F("Done!"));
  }
  while(serial.available()) serial.read();
}

void setup() {
  serial.begin(9600);
  delay(5000);
  setSyncProvider(RTC.get);  // the function to get the time from the RTC
  delay(200);
  adjustTime(-25200);
  pinMode(RELAY,OUTPUT);
  flash();
  powerON();
  delay(6000);
}

void loop() {
  static long nextRefresh;
  static long now;
  if (checkTimer.TRIGGERED) {
    rightNow = RTC.get();
    now = (long) rightNow;
    nextRefresh = readEE(NEXT_REFRESH);
    if ((now > nextRefresh) && (hour(rightNow) == 8)) {
      doRefresh();
    }
    else {
      powerON();
    }
  }
  if (serial.available()) processSerial();
  delay(500);
}

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

Here's an update on this project...

The new board design is working out well with one exception. It turns out that the ATTINY85 chip wouldn't start running it's code until I had first applied power to the circuit, then press the reset button. So I did some poking around and someone on the Arduino forum suggested putting a cap between the top of R4 and ground, but that didn't work, so I just removed R4 all together and that actually did the trick. So now the code starts running as soon as power is applied.

The way I know that the code is running, is I have it flash the lights a few times in the setup() routine.

As far as the code for the ATTINY, that was a little tricky. The chip cant store much code, so I had to use one program to set the DS3232 RTC to the correct date and time. then use a different program for actual daily use.

So I decided on doing the battery charge refresh once every six weeks (refresh cycle is three hours) and I use the ATTINY's EEPROM to store the Unix time code, which wasn't easy because each EEPROM storage location is not large enough to store a long datatype so I had to concatenate sequential addresses to be able to store the whole timecode. And the timecode is actually a future date.

The main loop periodically pulls down the current Unix timecode from the DS3232 and compares it with the future date in EEPROM, and if the current timecode is larger than the one stored in the EEPROM AND ALSO if the current hour is 8 AM, then it starts a refresh cycle. And that cycle, when it starts, calculates another six weeks and stores that back into EEPROM, and then it cuts power to the unit for two hours and that's about the gist of it all.

In order to kick off the first recording of the future date, when I burn the code to the chip, I first burn a bootloader, then the code, that way the initial reading of the EEPROM will be either 0 or -1, then when the code starts, it looks for a value less than 1000 or whatever and when it sees that, it starts the first refresh cycle which then calculates six weeks into the future, writes that to EEPROM and its all good.

The initial refresh worked fine ... so I won't actually know if the six-week thing works until it happens and if I'm around to see it.

Here it is installed in the unit ...

[sam_sam_sam]

Re: Swapping out a NiMh for a LiPo?

Gotta love it when someone is that dedicated to science!

Either that or just mad —> or just dose not have anything else to do

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

lol
like the youtube guy "project farm",
he reads package claims and says "we're gonna test that!"
#

Gotta love it when someone is that dedicated to science!

[stj]

Re: Swapping out a NiMh for a LiPo?

lol
like the youtube guy "project farm",
he reads package claims and says "we're gonna test that!"
#

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

umm....
that label is meant to be informative, not a challenge!!!

My motto is ... question EVERYTHING! :-)

[stj]

Re: Swapping out a NiMh for a LiPo?

umm....
that label is meant to be informative, not a challenge!!!

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

i hate those battery holders - you often hit the battery on something while trying to slide it out.
i use the type on pc's where you just drop the battery in past a latch

Yeah for whatever reason, this holder was the best one I could find at the time on Amazon. Then I had to create the object for EasyEDA and I had holes placed in the PCB where the three small studs or whatever stick out from the holder, but after seeing how it all works, I think those might have been meant to rest against the PCB and give it support. ALSO, don't hold onto any of the metal when you're soldering it to the board ... just an FYI on that! lol

I forgot to mention earlier that these batteries ... are everything there are advertised to be... I had to use a towel on my tongue after trying it out...

[stj]

Re: Swapping out a NiMh for a LiPo?

i hate those battery holders - you often hit the battery on something while trying to slide it out.
i use the type on pc's where you just drop the battery in past a latch

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

Update:

Got the re-designed PCBs and this is the first complete build...






Addedd access to two of the softSerial pins for easy inquiry and for setting the RTC.





Got rid of that microscopic piece of crap cap and put a real cap on there ...











And a video ...

Maybe it's my imagination but the green PCBs seem to be of a higher quality than the blue ones.

I'm gonna have 8 PCBs leftover and a lot of extra parts too ... it's a decent circuit for switching AC off and on up to 240V at 2 amps ... if anyone would like a PCB I can just put one in an envelope, stick a stamp on it and it gets there when it gets there ... if you want components, just pay my cost and ill include those as well ... up to what I have anyways.

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

One comment I have is that what I have read about doing circuit traces is that should have rounded curves and not square edges that come to a point

For the life of I can not remember the exact reason for this is

Yes, I've seen that stated before too ... but until someone can tell me WHY this should be the case ... then I call bullshit on it.

Certainly, in high-frequency circuits, trace layout could mean the difference between success and failure... but in raw DC switching applications? BAH!

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

you used an smd electrolytic - you terrorist!!!!

Not in version 2.0!

[Agent24]

Re: Swapping out a NiMh for a LiPo?

One comment I have is that what I have read about doing circuit traces is that should have rounded curves and not square edges that come to a point

For the life of I can not remember the exact reason for this is

Sharp inner corners (45 degrees and below) can create an "acid trap" that could cause undercutting of the trace during etching.

Also, sharp angles are no good for high frequency signals, so traces that must carry them are usually curved around corners instead of angled.

[sam_sam_sam]

Re: Swapping out a NiMh for a LiPo?

One comment I have is that what I have read about doing circuit traces is that should have rounded curves and not square edges that come to a point

For the life of I can not remember the exact reason for this is

[stj]

Re: Swapping out a NiMh for a LiPo?

you used an smd electrolytic - you terrorist!!!!

[EasyGoing1]

Re: Swapping out a NiMh for a LiPo?

An update on this thread ...

One of the circuit boards I ordered recently was the one to do this project... Though I screwed up on the schematic and cross-connected the input to the relay so I had to cut traces and jumper across to make it right.

Also, R5 ended up not being needed at all ... it was choking the voltage at the relay input and I learned a very important lesson in this venture ... SURFACE MOUNT COMPONENTS CAN REALLY SUCK SOMETIMES!

C1 is so friggin tiny, that I can't even pick it up with my fingers ... I must have lost 10 of them just trying to get one on the board ... I ended up just using the oven with some solder paste which actually worked out well.

Here are some pics ...








And this is the re-design ... got rid of that damn microcap and put a real cap in there ... fixed the leads to the relay, fattened up the traces a bit ... dumped R5 and its cap and bigger resistors cause they're easier to work with also added the ability to connect to serial on the ATTINY ...



OH, and those connector blocks ... are REALLY REALLY NICE ... they have some kind of mechanism in them so that when you pull on the wire, it somehow gets tighter ... I tried with all my might to rip the wire out once it was latched in there and it wasn't budging AT ALL. I have so many of them because of the required minimums but I think I had to purchase 50 of them at like 2 cents each or something ridiculous like that .... if anyone is interested in trying them, PM me your mailing address, and I'll send you a few ... they're pretty slick.

[eccerr0r]

Re: Swapping out a NiMh for a LiPo?

I'll need to see if I have one somewhere...ugh...

... and nope, dont think this open loop common emitter shunt regulator is accurate enough... need to have full control loop