[LIM PHANG MOH]

The article you pointed out is using an Arduino Pro Mini based on ATMega328P. Your’s is a Pro Micro.
Never had the chance to test with a Pro Micro yet, so I won’t know the exact figure. The regulator and the TLC5940 should have it’s quiescent current. Do check their datasheet.

[LIM PHANG MOH]

Just remember to add some delay in setup() like few seconds to provide enough time for you to upload code next time before it goes to sleep. Else you will have a bricked unit.

[LIM PHANG MOH]

1) Why does one need to detach the USB connection? Why isn’t it enough to simple attach it again – especially when you then see that the default detach method is empty?

Because without detaching the USB peripheral actually consumes additional current.

2) If I in my final design does not need the USB connection, should I then detach it anyway (e.g. in the Setup routine) to minimize sleep current?

Yes, you need them as the above.

3) Will Serial1 be working, or should that also be detach / attach – if so, do you also know the command for that?

No, you do not need to do that. Just make sure you use Serial1.flush() if you want to make sure characters are transmitted out before going into sleep. Else you might see some garbage characters.

4) Where is the different sleep modes in your library described (powerDown, idle, etc.)?

Take a look at our very old article here.

5) Can I do anything else (software-wise) to save power in sleep mode, than just calling:
LowPower.powerDown(SLEEP_FOREVER, ADC_OFF, BOD_OFF);

Take care of pins that are floating and make sure they are at a defined state (high or low).

[LIM PHANG MOH]

Hi julle.p,
Please take a look at my solution here.

You need to properly attach and detach the USB port.

[LIM PHANG MOH]

The library currently uses the WDT as an interrupt timer to wake up (SLEEP_8S, SLEEP_4S, etc) rather than a reset.
During non-sleep operation, you could use the WDT as a reset source but it’s not covered by the library. For sleep operation, instead of using SLEEP_FOREVER and depend solely on the external RTC, you could instead use SLEEP_xS instead although that is not the same as WDT reset but it uses the same exact WDT internal timer to do that.

[LIM PHANG MOH]

Try to upload a simple blink sketch to the board to get the board out of this state. You can do this by double pressing the reset button in quick succession after you press the upload button on the Arduino IDE. This works all the time.

Looking at your code, the code uses Serial instead of SerialUSB for debug information. So, unless you are connecting the Serial pins on the board to a USB-Serial converter, you won’t see anything if you connect the Mini Ultra Pro’s USB port to the IDE.

[LIM PHANG MOH]

Yes, you can replace it with a 16×2 as long as it is the 3.3V version.

small voltage displays connected to the control terminals of the SSR and the thermocouple terminals?

You can’t on the thermocouple terminals as they only few mV range. For the SSR terminal, as long as the small voltage display is not using it as power supply.

[LIM PHANG MOH]

That is good news, I will keep track of the progress on your new boards. Please check with the RN2903 if you can make it work in the Malaysian/Indonesian frequency. Although it is advertised as being able to run in the 915mHz range, when I bought them (3 months ago) they came pre-programmed with the US settings and so they don’t work out of the box.

After asking Microchip how to change it, because I couldn’t figure out how to, there wasn’t much in the docs, they said I had to update the firmware and they advised me to write it myself because they had none for AS923. Needless to say I wasn’t happy about this, also because it took them over two weeks to respond to this question. Note that this is for LoraWAN, when using Lora only you can change the frequency.

Let me check with them on this. I know AS923 support or even AU915 is missing.

Long story short, although they look easy to use with the TX/RX build in support. For us costs wise and limitations on software adjustments actually made us abandon our custom build boards around this chip. Hence I moved on and started ordering your boards with the RFM95 chip 🙂

I still believe people would still want the RFM95W version. As many people run RadioHead library instead of the LoRaWAN LMIC. It won’t be that hard to do a version with the RFM95W. Also I forgot to mention, board will also be able to run on non-rechargeable batteries like 2xAA, 3xAA, CR123A, Li-SOCL2. This will leave user with a wider temperature range and various battery chemistry to select from based on different requirements, cost and scenario.

[LIM PHANG MOH]

Hi Roy,

I’m currently working on it but it will come with an RN2483A/RN2903 instead of the RFM95W to make it easier for mass deployment. Supports Li-Ion/Pol, 2 cell NiMH (not sure whether 3 cell is desired), or LiFePO4 (only 1 configuration at a time). Trying to push down the sleep current consumption at the moment. Board is 4-layer PCB, so there are more work on validating everything. And yes, input is solar compatible so if the sunlight is less, the input voltage will not collapse.

[LIM PHANG MOH]

Hi Francisco,

That is a very old meter of mine. I would recommend other newer meters. Depending on your budget and needs, entry level meter like Brymen 235 is a very good meter. If you need higher precision, more expensive ones like Fluke 87V and Brymen 869S are the meter to go to. On even higher even range, benchtop multimeter is a very nice instrument to have.

[LIM PHANG MOH]

The green LED (power Good, PG) is controlled the power path management IC BQ24074. We won’t be able to control them on software. The only way is to de-solder the LED current limiting resistor 2.2K R12.

• This reply was modified 8 years, 2 months ago by LIM PHANG MOH.
• This reply was modified 8 years, 2 months ago by LIM PHANG MOH.
• This reply was modified 8 years, 2 months ago by LIM PHANG MOH.
• This reply was modified 8 years, 2 months ago by LIM PHANG MOH.
• This reply was modified 8 years, 2 months ago by LIM PHANG MOH.
• This reply was modified 8 years, 2 months ago by LIM PHANG MOH.

[LIM PHANG MOH]

Hi Brett,

Would be very interested in a LiFePO4 version but also if you are already looking into it LTO support (though there aren’t any chipsets I can find for it yet) would be even better. The cold performance and charge cycling ability of those batteries is super amazing.

I did look into LTO too. But, I’m looking at a chip currently that supports Li-Ion/Pol, NiMH and LiFePO4. Unfortunately, LTO support is on another separate chip. To support the 3 battery chemistry above, only some configuration components will be different, That would allow me to use a single design but different components are populated based on different battery chemistry. And yes, LiFePO4 and LTO battery charger are less in the market. And to make things worst, I needed a solar panel input compatible (MPPT) and ultra low current uA range. That makes things harder but I’m working on it.

The driving force behind this decision is definitely temperature as you have mentioned. The number of charge cycle is also way much better than Li-Ion/Pol batteries.

There’s no ETA just yet but samples chip are coming in. So, I’m evaluating….

[LIM PHANG MOH]

Hi,

Using VIN, it will be 1.5 mA nominally with VIN at 6V. You can take a look at this section of the datasheet of the power path IC BQ24074. So, that’s the best you could get unfortunately.

Usually VIN is considered as the 2nd source of power like solar and DC voltage.

As more and more people are requesting for LiFePO4 usage, I’m currently looking into possible version of using LiFePO4 and NiMH also. But, currently still in development.

[LIM PHANG MOH]

Hi!

The JST connector can only be used with Li-Ion or Li-Pol that has a maximum voltage of 4.2V and nominal voltage of 3.7 V. If you used it on VIN, then it is okay but it becomes the charging source in this case.

Do take note, when powering from VIN or VUSB, you won’t be getting the 18 uA of sleep current. Only when a valid Li-Ion/Pol is used on the JST connector, the desired 18 uA of sleep current can be achieved.

[LIM PHANG MOH]

I’m referring to the ATMega328P datasheet. I think I was referring to the older datasheet. On the latest datasheet it is on section 28.9.8 at page 326.

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