[Shannon Hicks]

This is interesting, thanks for the information Paul. I haven’t encountered this problem with any of the recent Aruino IDE builds as of a few months ago, but I’ll try it with the latest one and see if I can resolve the issue.

[Shannon Hicks]

That looks like a great sensor. Powering the sensor from the Mayfly battery is probably possible, but at 100ma, it’s toward the upper end of the max operating current of the 5-volt boost circuitry, but it looks like you could power it from either the constant 3.3v rail or using the 3.3v switching circuitry. The bigger issue would be if you wanted to run the sensor continuously or if it’s only going to be sampled for short bursts, with longer power-downs between samples. If you power the Mayfly with a big (4000maH or greater) lithium battery or a pack of C-size batteries, you could get several days of continuously-powered operation. If you only use the sensor for a few seconds every few minutes, then you could get by with smaller batteries and a solar panel and unlimited duration. It all depends on the sample time and sleep duration.

As for measuring the output of the sensor, there are a couple different options. One would be to put the sensor output across a resistor divider that drops the 5v to 3.3v (i.e. a 10k and 20k resistor in series across the sensor output, so when the sensor outputs a max of 5v, the voltage between the two resistors is 2/3 of that, which is 3.3v). Or you could add a separate ADC board (like the Adafruit ADS1115 breakout board). Power the breakout board from the 5v switched output of the Mayfly and then it will be able to handle a max input of 5v. But you’d need to connect the breakout to the I2C port of the Mayfly, so you’d need to add some digital level-shifting on those 2 I2C lines to protect the Mayfly from higher voltage of the breakout. I’m sure there are a few other methods, but those are the two quickest and easiest.

[Shannon Hicks]

When a Mayfly board is asleep, it draws around 0.27mA. If you have a microSD card in the socket, the card draws a little current on its own, so then the Mayfly draws around 0.43mA when sleeping with a card.

When the Mayfly is awake and idle, it draws 6.5mA.

Battery life in a deployment would depend on the size of the battery and what sensors or other devices you’re powering with the Mayfly. You can do some estimations at this site: Oregon Embedded Battery Life Calculator. Just plug in the above numbers for the Mayfly, your battery capacity, and information about the waking time.

[Shannon Hicks]

I would highly recommend the GPRSbee Rev 6. It has a much easier (and more reliable!) method for waking and sleeping the GPRSbee than the Rev 4 board. Plus the Rev 6 has a u.fl antenna connector instead of the SMA that the Rev4 has, so it’s much easier to fit it inside the Mayfly enclosure. I’m deployed 6 Mayfly loggers with GPRSbee’s last week and will be putting in 3 more tomorrow. So I’ve got plenty of photos of the process and example sketches. I just need some time to publish the instructions when I’m not in the field doing installations! Hopefully I can post a couple basic sketches later this week with more detailed instructions soon after.

As for sources, we still plan to offer kits soon with the GPRSbee in them, but for now I’d suggest you order them from SODAQ or Seeedstudio.

[Shannon Hicks]

What version of the GPRSbee do you have? The latest hardware version uses different code commands for toggling it on and off. I’ve successfully used the latest 3 versions of the GPRSbee with the Mayfly so I can send you the appropriate code for your model.

[Shannon Hicks]

We have been using a homemade database system that I developed a few years ago, and it’s not ready for widespread release just yet. So in the meantime, you can probably use Thingspeak, but I also know of some people who have successfully used Sparkfun’s data portal (https://data.sparkfun.com/) for streaming Mayfly data from either a wifi bee or a GPRSbee.

[Shannon Hicks]

For most of my loggers, I use a 1200mah or 2500mah battery, depending on how much power the external sensors draw, what size solar panel I’m using, and how shady the deployment site might be.

I’m optimizing and documenting the sleeping logger Arduino code and will post it as soon as it is ready.

[Shannon Hicks]

Do you have board version 0.3 or o.4? There may be a very small number of the v0.3 boards that have a bad connection in the power switch where it provides power to the FTDI chip, so the Mayfly will not be seen by the computer as having a valid serial port. Does the Mayfly at least blink the red and green LEDs when it’s plugged in to either a USB cable or a lipo battery? Do you have an FTDI cable or FTDI adapter that you can use to program the Mayfly using the FTDI header? That will bypass the FTDI chip on the board and allow you to program it. I programmed each v0.3 Mayfly on Amazon via the FTDI header so it should work. I programmed all of the v0.4 boards via the microUSB jack to verify tha each one was working properly.

[Shannon Hicks]

I haven’t had a chance to make a table of all of the power usage data from my tests, but here are some of the more important measurements:

Mayfly current when board is powered and idle: 6.5 mA
Mayfly current when MCU put to sleep: 0.27 mA (or 270 uA)
Current when asleep with microSD card in the socket: 0.43 mA (or 430 uA)

[Shannon Hicks]

Check out this ultrasonic sensor example I just posted. It shows how to read the serial output of a Maxbotix sensor. I like to use the MB7386 and MB7389 sensors because they have the TTL output that can be read directly by the Mayfly. The MB7360 you mentioned only has RS232 output, so you’ll need a RS232-to-TTL converter between the sensor and the Mayfly.

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