A few weeks ago we found that some of the version 0.3 Mayfly boards were assembled by the manufacturer with an incorrect voltage regulator on the section of the board that generates the switched 5-volt boosted supply. This error does not affect any other functionality or features on the Mayfly. The only issue is that you will see 3.3 volts on the “Sw_5v” pin instead of 5 volts.
We have also found a very small number of boards that experience intermittent power glitches when touching the main power slide switch. On some boards this is only apparent when the board is being powered by the microUSB cable, and other boards see this behavior on battery power. The board manufacturer said this switch failure was caused by one of the steps in their assembly process, so we are taking steps to prevent this issue in future orders.
We think that most of the v0.3 boards in the Amazon inventory that were sold in June 2016 had the incorrect regulator, but only a very small number might have the power switch issue. If you purchased a v0.3 Mayfly board in June and you experience power glitches related to the main power slide switch, or if you need the 5-volt boost functionality, we are offering a free exchange of your old board with a brand new version 0.4 Mayfly board. The version 0.4 board fixes the 5-volt regulator issue, plus we have performed extensive testing of every board to ensure that they have none of the issues the we or other users have found with the version 0.3 board.
If you would like to exchange your board, please send an email to firstname.lastname@example.org and tell us how many boards you ordered and include an address for us to send the replacement(s). We will mail you a box with prepaid return postage so that you can return the old defective boards to us. If you aren’t using the 5-volt boost feature and you don’t have any glitches with the power switch, then there is no reason for you to return your board.
We have removed all of the affected v0.3 boards from the Amazon inventory and have replaced them with tested v0.4 boards.
The version 0.3 board was our first large production run of boards, and we appreciate everyone’s patience and understanding while we work out the bugs.
Reminder: Most users of the Mayfly board will likely not use the switched 5-volt supply feature since all of the input/output pins of the main Mayfly processor are not 5-volt tolerant, which means that you should never connect any signals greater than 3.3 volts to the I/O pins of the Mayfly. The 5-volt boost circuit was only put on the Mayfly to give experienced users the ability to power external sensors or other devices that need a higher supply voltage. However, it is up to the end user to verify that their external device will not be returning any 5-volt signals back to the Mayfly, which includes any data lines. To protect the data lines, the end user will need to provide separate voltage level shifting circuitry or other techniques to maintain 3.3v TTL levels to the Mayfly I/O pins. Only experienced users should attempt to use the 5v supply or make changes to the Grove connector power selection jumpers.