[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.

[Shannon Hicks]

We have had very good results with the GPRSbee module from SODAQ. It’s a 2G board and SODAQ also has a new 3G board with the same Bee footprint so it could also work with the Mayfly. We have deployed many stations with the GBRSbee board along with a SIM card from a company that offers a low-cost data plan, so the loggers can push data into our custom online database every 5 minutes. They work anywhere that there’s a decent AT&T or T-Mobile signal. Verizon uses different hardware and also doesn’t permit devices like this on their network anyway.

We plan to offer kits later this month that include a GPRSbee and SIM card, along with publishing a tutorial for how to build the logger stations that use the Xbee and/or cellular modules.

[Shannon Hicks]

I have done some thorough testing of the battery holders on the original v0.3 boards and the new v0.4 boards and found that it’s the texture of the bottom of the battery that makes the difference. It appears that one brand of battery might have some problems making good contact with the board, but this isn’t limited to the Mayfly. I tested 3 different brands of batteries and I found that one of them is almost smooth of the bottom, whereas the other two have a bumpy texture in the metal. See the attached photo for a comparison between two of them.

What I found was that the smooth-bottom battery sometimes has trouble making good contact when inserted into the Mayfly battery socket. I inserted the bumpy-bottom battery into over 100 Mayfly boards and every one of them worked perfectly. I also had trouble with the smooth battery in a few other devices that were not made by us, so I think the problem is caused by the battery and not specifically the Mayfly board. In every case where the battery wouldn’t make contact, putting a small bit of solder on either the battery or on the board under the holder immediately fixed the connection issue.

Attachments:

1. 

   battery_comparison-Medium.jpg
   

[Shannon Hicks]

See my latest blog post for information about exchanging the v0.3 Mayfly boards for the new v0.4 boards. I will also be emailing all of the Amazon customers today with information about the exchange.

[Shannon Hicks]

Pins 10, 11, 12, and 13 on the Stalker are used by the SPIbus, so if you’re want to use the microSD card socket, you can’t use those digital pins for anything else. It’s been awhile since I looked at the specs of the Stalker, but I think there are very few free pins. That’s one of the reasons we stopped using it and created the Mayfly. And the Mayfly’s secondary hardware serial port makes it easier since you can sometime avoid using the SoftwareSerial functions if you just have one serial device to interface with.

The Mayfly boards should be available again on Amazon by this weekend.

[Shannon Hicks]

If you measure 3.3v on the Sw_5v pin, then unfortunately you have a board with the incorrect regulator. There’s no way to get your board to generate 5v unless you replace the regulator. While it is possible to replace it if you have the right tools and you have experience removing and replacing a SOT-23 surface mount device. However, we have new boards with the correct part that we have shipped to Amazon to replace the existing inventory. I will also be contacting each customer directly through Amazon to tell them how they can exchange any affected boards for a new one.

Keep in mind that most users will not need to use the 5v setting on the Grove connector jumper. The Mayfly is not tolerant of 5v I/O signals, so any peripheral devices you connect must not send any voltage greater than 3.3v back to the Mayfly I/O pins. The 5v options is only there for experienced users who can ensure that they have proper level-shifting circuitry or other protective measures to ensure that the Mayfly only sees 3.3v signals. In my case, I use several analog sensors that need to be powered by 5v supply, but only output a 0-2.5v signal. Other digital sensors that require 5v will be connected to a level-shifting adapter board via the Grove connector.

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