Home › Forums › Mayfly Data Logger › pc and Mac unable to communicate with mayfly ver. 0.5b › Reply To: pc and Mac unable to communicate with mayfly ver. 0.5b
If there’s a CR1220 watch battery installed in the battery slot on the Mayfly (with sufficient voltage) then the RS3231 RTC will still be alive and continuing to think it’s whatever time it thinks it is. However if the board has been sitting in storage for awhile and not attached to a main Lipo battery, it’s likely that the CR1220 is dead and therefore the RTC doesn’t retain any time information, and it will reset itself to 1/1/2000 every time the Mayfly starts up until you add a new CR1220 and set the clock. If there’s a cellular modem on the Mayfly board, then it will attempt the contact the time server to set the RTC upon bootup (assuming you’re running one of our recommended sketches built on the ModularSensors examples we share on Github).
If the clock is still running but is just wrong because the clock was set wrong sometime in the past, you could see what time is currently being reported, then do the math (easiest in Excel) to get the offset between the correct NOW time and the incorrect NOW time, and then apply that offset to all of the stored data on the logger’s memory card. If your Mayfly is running one of those recommended logger sketches, then it will print a variety of helpful information to the Serial Monitor upon startup, including the date/time of the RTC, and other configuration settings of the deployment. If you reprogram the Mayfly with another sketch before you see any of that, then it’ll be lost, so I’d recommend only trying to read the data from the Mayfly serial port until you get things going smoothly with the computer and not trying to upload any new sketches until you’re able to connect reliably and correctly to the Mayfly with the USB port on your computer. The previous sketch is probably transmitting at either 115200 or 5600 baud. That speed only refers to comunications through the Serial Monitor and doesn’t affect the upload speed used when burning a new sketch to the board.