# 1mhz hardware

• I recently flashed an arduino pro mini bootloader to 1mhz. This in the end did what I wanted, which was low power. However, I am still noticing something odd and believe I have missed something.

I have this line in my loop

``````whichbutton = sleep(digitalPinToInterrupt(2),LOW,digitalPinToInterrupt(3),LOW,3600000);//86400000);
``````

Doesn't seem to be waking up as expected. It does wake up, but not quite on the hour like I would have expected. But it still wakes up on interrupt which is the important thing.

The other thing I am curious about is I have the following for checking my battery. Which works, but I have a question regarding the percent. Is the percent based on the actual drop out voltage? For instance, I have a 3v battery. My fuses are set to 1.8v for dropout. Is the battery percentage basing 0% at 1.8v or 0v?

``````void CheckBattery()
{
// battery stuff
// get the battery Voltage
#ifdef MY_DEBUG
Serial.println(sensorValue);
#endif

// 1M, 470K divider across battery and using internal ADC ref of 1.1V
// Sense point is bypassed with 0.1 uF cap to reduce noise at that point
// ((1e6+470e3)/470e3)*1.1 = Vmax = 3.44 Volts
// 3.44/1023 = Volts per bit = 0.003363075

int batteryPcnt = sensorValue / 10;

#ifdef MY_DEBUG
float batteryV  = sensorValue * 0.0029325513196481;
Serial.print("Battery Voltage: ");
Serial.print(batteryV);
Serial.println(" V");

Serial.print("Battery percent: ");
Serial.print(batteryPcnt);
Serial.println(" %");
#endif

if (oldBatteryPcnt != batteryPcnt) {
// Power up radio after sleep
sendBatteryLevel(batteryPcnt);
oldBatteryPcnt = batteryPcnt;
}

}```

@Nca78``````

• @Jason-Brunk said:

It does wake up, but not quite on the hour

Can you be more explicit? How much time is there inbetween wakeups? The watchdog will always be a bit off, but it should only be a few %

• Did you change the board definition within the Arduino IDE so that the code is compiled for 1 MHz? If not, the timing wont match.

According battery:

100 % = Vmax = 3.44 Volts
0 % = 0 V

• Hello, no idea with the wake up time, I didn't check it at 1MHz, but it should not vary as it's based on the watchdog timer which is always at 128KHz, and not related to the main clock frequency and multiplier.

For the battery level do you use a divider ? That's useful if you have a booster, but for a CR2032 directly connected to Vcc the most simple way is to measure the supply voltage. Please note that my measurement is not exact as value should be adjusted to the exact voltage of the "1.1V" reference voltage of the atmega.

``````#include <SystemStatus.h>
// Parameters for VCC measurement
const int VccMin        = 2000;  // Minimum expected Vcc level, in Volts. At 2V the cell should be dead
const int VccMax        = 2900;  // Maximum expected Vcc level, in Volts.
SystemStatus vcc();
int LastBatteryPercent = 200; // so we are sure to send the battery level at first check

int currentBatteryPercent = SystemStatus().getVCCPercent(VccMin, VccMax);
if (currentBatteryPercent != LastBatteryPercent) {
LastBatteryPercent = currentBatteryPercent;
sendBatteryLevel(currentBatteryPercent);
}

``````

• @TimO Here is my definition in my boards.txt

``````## Arduino Pro or Pro Mini (1.8V, 1 MHz) w/ ATmega328
## --------------------------------------------------

``````

• @Nca78 yes currently using a voltage divider. if i go to measuring the supply voltage alone that will get rid of the extra components I may not be needing atleast for this node.

I will try your example. Thanks!

• @Yveaux Ok. so it checked in at 3:17am this morning. it did not check in again until 1:58 this afternoon.

• @Jason-Brunk that's almost 10 hours. My guess is that the timer is 8x off (if the code expects 8Mhz but is running at 1Mhz). Try recompiling with 1MHz board settings or divide the time by 8 in the sketch)

• @mfalkvidd Ill reflash it. Just wondering if there is something in the code I should change to tell it it's running at 1mhz or if that's something that is supposed to just work based on the clock timing

• @Jason-Brunk I think the Arduino IDE is supposed to handle all that if the correct board is selected. I know that timings are off if I select 16MHz pro mini in the IDE and then flash to a 8MHz Arduino. It is also easily noticeable on the serial monitor, which will require a setting of twice the baud rate set in Serial.begin. I have never built a 1MHz node though.

• @Jason-Brunk why not falsh your node for internal 8mhz for instance, and then use 1Mhz in sketch ? On my side, I prefer this way..and it works for me at least.
when the node is not sleeping, and radio is not sleeping in RX mode for instance, there is no big saving to do this, only atmel consumption is low, radio is not..but if your radio is sleeping, yep it's interesting but I don't really see advantage to start node at 1Mhz as the radio does not sleep at startup and does the protocol stuff.

• @Jason-Brunk said:

Just wondering if there is something in the code I should change to tell it it's running at 1mhz or if that's something that is supposed to just work based on the clock timing

Clock settings are determined by the"fuses". What's your tool for fuses and bootloader programming? Are you sure you programmed the fuses as in your "boards.txt" above?

• @m26872 said:

@Jason-Brunk said:

Just wondering if there is something in the code I should change to tell it it's running at 1mhz or if that's something that is supposed to just work based on the clock timing

Clock settings are determined by the"fuses". What's your tool for fuses and bootloader programming? Are you sure you programmed the fuses as in your "boards.txt" above?

My understanding was that the "burn bootloader" function of the Arduino IDE will also write the fuses, no ?

From Arduino website :
"How does it work?

The "Burn Bootloader" commands in the Arduino environment use an open-source tool, avrdude. There are four steps: unlocking the bootloader section of the chip, setting the the fuses on the chip, uploading the bootloader code to the chip, and locking the bootloader section of the chip"

• @Nca78 True. And I suppose you've also double checked the verbose output from that process.

• Ok. So I got back in town and reflashed my bootloader. Claims it's running 1mhz now. No regulator, no leds. Even in sleep mode I am sitting at about 1.66ma. Which in deep sleep mode that seems really high. Considering the capacity of a coin cell i am looking at changing out about once every 2 weeks with no use.

Any thoughts? Recommendations? Just can't seem to get this running low power enough. Not sure if my hardware is junk or what. But i would take any recommendations or tests to see how to get this working since i have a small stack of these pro minis

• There's obviously a problem, I'm at about 1/1000 of that in sleep mode, you're sure your multimeter is not mistaking the unit ?
I have cheap pro minis too, the < 2\$ kind.

1mA+ in sleep mode sounds like a voltage regulator still connected, or the IC not sleeping, at least not in power down mode like when using the MySensors function. Are you sure you didn't leave a #define by mistake (like activating the repeater function with #define MY_REPEATER_FEATURE) that would prevent the atmega from sleeping ?

• I checked, no REPEATER on.

Here is the code for my loop()

``````int whichbutton = 0;

whichbutton = sleep(digitalPinToInterrupt(2),LOW,digitalPinToInterrupt(3),LOW,86400000);

switch (whichbutton) {
case digitalPinToInterrupt(2):
{//off
send(msg_light.set(0),true);
wait(300);
break;
}
case digitalPinToInterrupt(3):
{//on
send(msg_light.set(1),true);
wait(300);
break;
}

}
sleep(250);
CheckBattery();
``````

It's not running that over and over for sure. Otherwise I would see the battery value publishing regularly to the broker.

I broke the regulator off and the LEDs.
This is the one I have.
https://www.sparkfun.com/products/11114

I don't think the multimeter is misreading it. I can see the battery percentage dropping over the course of a day so it definitely seems like it's pulling more mA than it should sleeping.

• @m26872 said:

@Nca78 True. And I suppose you've also double checked the verbose output from that process.

In case someone doesn't believe the Arduino docs
This is at the beginning of the bootloader writing process in Arduino IDE:

``````Writing | ################################################## | 100% 0.01s

avrdude: 1 bytes of efuse written
avrdude: verifying efuse memory against 0x06:
avrdude: load data efuse data from input file 0x06:
avrdude: input file 0x06 contains 1 bytes

Reading | ################################################## | 100% 0.01s

avrdude: verifying ...
avrdude: 1 bytes of efuse verified
avrdude: writing hfuse (1 bytes):

Writing | ################################################## | 100% 0.01s

avrdude: 1 bytes of hfuse written
avrdude: verifying hfuse memory against 0xde:
avrdude: load data hfuse data from input file 0xde:
avrdude: input file 0xde contains 1 bytes

Reading | ################################################## | 100% 0.01s

avrdude: verifying ...
avrdude: 1 bytes of hfuse verified
avrdude: writing lfuse (1 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 1 bytes of lfuse written
avrdude: verifying lfuse memory against 0x62:
avrdude: load data lfuse data from input file 0x62:
avrdude: input file 0x62 contains 1 bytes
``````

• @Nca78
The docs won't tell you if the process fails. The verbose output will.

• hmmm. ok so I have verified I am writing the 1mhz boot loader.

My multimeter says when it's sleeping i am still running at 1.5mah

I have my openhab system tracking the battery usage. IN 6 days I have lost 30% of the battery and it's been in sleep mode.

``````|| *Time* || *Value* ||
|| 2016-08-14 19:29:27 || 100 ||
|| 2016-08-15 19:07:57 || 80 ||
|| 2016-08-15 19:11:18 || 81 ||
|| 2016-08-15 19:12:48 || 83 ||
|| 2016-08-15 19:13:14 || 76 ||
|| 2016-08-15 19:13:17 || 84 ||
|| 2016-08-15 19:13:56 || 80 ||
|| 2016-08-15 19:16:48 || 78 ||
|| 2016-08-19 15:07:57 || 76 ||
|| 2016-08-19 15:10:09 || 80 ||
|| 2016-08-19 15:12:43 || 79 ||
|| 2016-08-19 15:13:49 || 82 ||
|| 2016-08-19 15:14:20 || 84 ||
|| 2016-08-20 11:44:01 || 69 ||
|| 2016-08-20 11:44:23 || 48 ||
|| 2016-08-20 11:44:31 || 71 ||

``````

Any thoughts? Any recommendations on maybe a replacement pro mini that will for sure run at <1mah?

• remove the power led (1-2mA), remove the voltage regulator if possible (1mA)

• @cimba007 Led was already removed.

• I would only imagine that the VoltageRegulator might be the culprit.

As you said you use a "3v battery" so there is no need for the VoltageRegulator at all. Where do you apply the power? RAW or VCC? To power your Arduino with higher voltages you connect them to RAW which leads to the regulator.

On most of my projects I use 2x AA Battery which are connected directly to VCC .. even with the VoltageRegulator intact I am at 66% for the last 7 days .. not loosing a single %.

PS: Sry .. I missed that you have already removed the voltage regulator + the led.
The library states to use RISING, FALLING, CHANGE as the interrupt mode but you use LOW .. I don't know to which of the 3 this mapps.

But my guess is you are using FALLING .. thus waking your node up if you connect pin 2 or 3 to ground .. which means you have some kind of pull up don't you?

Do you have anything connected to the Arduino ProMini? If so maybe try an empty sketch and remove all connected peripherals. Maybe even you can find some inspiration on this link: http://electronics.stackexchange.com/questions/49182/how-can-i-get-my-atmega328-to-run-for-a-year-on-batteries

Another really good test on the powerdown current is here:

http://www.rocketscream.com/blog/2011/07/04/lightweight-low-power-arduino-library/

with this library (not compatible with mysensor so dont't use at the same time)

https://github.com/rocketscream/Low-Power

• @cimba007 thanks! will definitely test out some of this stuff. I am connecting power to vcc and the regulator has been removed.

2 buttons connected to the interrupt pins, 1 for on 1 for off.

here is my sleep statement

``````whichbutton = sleep(digitalPinToInterrupt(2),LOW,digitalPinToInterrupt(3),LOW,86400000);
``````

Could my resistors connected to the buttons be causing the extra power?

I would expect that to be the cause because even a door sensor or something would have to trigger the interrupt.

A buddy of mine suggested I throw an additional multimeter in line so i am actually measuring with 2 and see if maybe my readings are just off or my multimeter is wonky reading it. He thinks maybe the fact i am measuring it is causing the extra current... (sounds like quantum entanglement stuff there, "It changed cause you measured it!!")

• Putting a multimeter in series will most likeley only cause a voltage drop of up to 200mV (just a rough number). If your circuit draws very little current even routing this current trough the resistor (which is causing the voltage drop) would not result in additional consumption.

Lets look at your switches .. if you are using a setup like this:

http://www.starting-point-systems.com/images/pullup_example.gif

http://www.microchip.com/forums/m341654.aspx states that there should be zero current consumption while the button is not pressed. Are u using this button setup? If not can u provide a drawing?

I don't think that the multimeter is to blame. You reported a very weak batterylife even when you are not measuring the current I guess.

``````He thinks maybe the fact i am measuring it is causing the extra current... (sounds like quantum entanglement stuff there, "It changed cause you measured it!!")
``````

Long story short .. I would not suspect the burden Voltage to be the problem .. I can measure in the 200ÂµA range with my cheapish Multimeter when the Atmega328p is in deep sleep mode .. so something must be drawing current in your setup.

• To get the fastest results I would try to disconnect everything from your circuit .. hook up the Multimeter to measure current in lets say 200mA range (if available) and try the deep sleep example from https://github.com/rocketscream/Low-Power

If the pro mini is in deep sleep mode you can switch from 200mA to 2mA or even 200ÂµA range if available. (just don't let the pro mini wake up while you have the range set very low)

Lower measure range = higher burden voltage = potential less power for your ÂµC .. maybe even to the point it will go into brown out or start to behave strange

• @cimba007 Thanks for the details. Let me get you back some info.

yes, my buttons are setup like the pullup example image

i didn't think the multimeter would do it, but at this point i am willing to try anything

I will pull my mini tonight and remove everything and do a test.

my code only wakes up when button is pressed or every 24 hours. so it shouldn't come on while testing. Ill try with my code and with the sleep example you referenced.

Thanks!!!!