Electronics_Projects_2020/Attiny_Solar_Energy_Harvest/docs/5.tex

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%\title{\textbf{Door Alarm}}
\author{Steak Electronics}
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\textcolor{green!60!blue!70}{
  \section{Attiny Solar Energy Harvest Tests}}

I have the following:
\begin{itemize}
\item Solar panels
\item Attiny 10
\end{itemize}
To this list, I will add a supercap, and an energy harvesting IC. The goal being to load the super cap during the day, and to run 24/7. I will need an exceptionally low power micro. The super cap will need to be about 3.3V or 5V.
\textcolor{green!60!blue!70}{
\subsection{Micro Considerations}}
The Arduino Atmega328P is not an option. I'm looking to have a current draw of only 1mA max, (ideally 500uA) when active. Moteino is also not an option for this. Those are made for batteries. I want to be battery free. A super cap, however can be used to store energy. I'll get to that shortly.

For micros, I have some Attiny10 on hand, and these have a reasonably low power pull in active mode. Let's build those up first. What will the micro do? No idea. I haven't a clue.

\textcolor{green!60!blue!70}{
\subsubsection{Micro Notes}}
Must run at 1.8V / 1MHz per front page of data sheet, for 200uA draw in active mode.
\\
\\


\textcolor{green!60!blue!70}{
\subsection{Energy Storage}}
I don't want a battery. Let's go with a super cap. The solar panels will only be active some of the time, so I will want to harvest energy with some kind of IC into the cap when the sun is out.\footnote{Reference: www.analog.com/media/en/technical-documentation/technical-articles/solarenergyharvesting.pdf is a start. I'll need to do more research.}

\textcolor{green!60!blue!70}{ \subsection{Make parts, not scrap}} I will 
want to make sure that all parts I build are perf board parts, not 
breadboard scrap (to be torn down and rebuilt again). This is an Attiny, 
so no need to test much, yet.

\textcolor{green!60!blue!70}{ \subsubsection{Testing Arduino Loader}}
Tested this with the blink_LED.c in code folder. The code is as simple as possible. 
It is the following:
\begin{verbatim}
//#include <xc.h>
#include <avr/io.h>
#include <util/delay.h>

int main(void)
{
    // PB2 output
    DDRB = 1<<2;

    while(1)
    {
        // Toggle PB2
        PINB = 1<<2;
        _delay_ms(500);
    }
}
\end{verbatim}
When programmed in Mplab, with XC8 compiler, and Attiny10 support, I get the following
hex output:
\begin{verbatim}
:100000000AC020C01FC01EC01DC01CC01BC01AC01B
:1000100019C018C017C011271FBFCFE5D0E0DEBF41
:0A002000CDBF03D000C0F894FFCF5D
:10002A0044E041B940B95FE966E871E05150604087
:0A003A007040E1F700C00000F5CFB0
:02004400DDCF0E
:00000001FF
\end{verbatim}
The content of this hex isn't the focus of this passage. Instead, I want you to review the 
results of a D for Dump Memory, by the Arduino Loader.
\begin{verbatim}

Current memory state:

registers, SRAM
      +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F
0000: 05 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0030: 00 00 00 00 00 00 03 00 00 79 00 03 00 00 00 00 
0040: B7 AD AE FA 58 70 63 6B FB 5A B4 1B FF FF 35 3F 
0050: 67 D7 33 43 DF 5F FB 72 C9 7D FE E9 9D C5 00 12 
NVM lock
      +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F
3F00: FF FF 
configuration
      +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F
3F40: FF FF 
calibration
      +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F
3F80: 79 FF 
device ID
      +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F
3FC0: 1E 90 03 FF 
program
      +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F
4000: 0A C0 20 C0 1F C0 1E C0 1D C0 1C C0 1B C0 1A C0 
4010: 19 C0 18 C0 17 C0 11 27 1F BF CF E5 D0 E0 DE BF 
4020: CD BF 03 D0 00 C0 F8 94 FF CF 44 E0 41 B9 40 B9 
4030: 5F E9 66 E8 71 E0 51 50 60 40 70 40 E1 F7 00 C0 
4040: 00 00 F5 CF DD CF FF FF FF FF FF FF FF FF FF FF 
4050: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 
4060: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 
(...some memory omitted here for brevity...)
43E0: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 
43F0: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
\end{verbatim}

Notice that the "AC020C01F" is set. That is from the hex. But the 01000...
before it seems to be missing. Some deciphering of how the Arduino programs
the Attiny is in order here. It also doesn't end the same.

Regardless, when programming, the Arduino reports 70 bytes written, and
likewise in the Mplab project memorymap.xml file, it also notes 70 bytes
for the sketch. This lines up.\footnote{Although for an unknown reason, every command registers twice on the Arduino serial monitor, but this appears to be harmless.}

The blinking LED works. Let's move on.

\textcolor{green!60!blue!70}{ \subsubsection{IO Port Switching Speed}}
Using the above code without any delay_ms, I get the following results from a default clock
speed, and a 128KHz clock speed. This test was done to confirm that I could change the clock with
\begin{verbatim}
    //Write CCP
    CCP = 0xD8;
    //change CLK to 128KHz
    CLKMSR = 0b01;
\end{verbatim}
There was no issue.
\begin{verbatim}
Default CLK (8MHz? or 1MHz?): 160KHz IO Switch
128KHz CLK: 2.5KHz IO Switch
\end{verbatim}
I am going to pursue 128KHz for starters, for lower current dissipation. Note that with the Arduino loader, it is cumbersome to test and change code as you move along. It is
therefore going to be necessary to use a programmer, with a dedicated header on board.
\textcolor{green!60!blue!70}{ \subsubsection{VCC 1.8V}}
The lowest power supported: 1.8V can be applied, without any configuration
needed. It does not affect IO switching speed (although obviously amplitude is affected).
\begin{verbatim}
128KHz CLK (5.0V): 2.5256  KHz IO switch
128KHz CLK (3.3V): 2.5477  KHz IO switch
128KHz CLK (1.8V): 2.5849  KHz IO switch
\end{verbatim}
As voltage drops, IO increases.
\\
\textbf{VCC Dropout voltage:}
From 1.5, it drops out at 1.248V or so. Comes back at about 1.34V
\\
Test size of 1.
\\
Can't run this with one (AA) battery, but you could with 2.
\\
Current Draw: 128KHz - IO test, 1.8V, 0.08mA (~78uA) (tested w/3478A)
\\





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