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Jumper settings

Note:  there are 2 sections on this page:  The top half is for the newest Mayfly v1.0 boards (released October 2021), and the bottom half is for the original Mayfly v0.5b boards (for boards bought between 2016 and 2020).

Mayfly v1.0

On the back of the Mayfly v1.0 (revA3) there are 20 user-configurable solder jumpers.  All solder jumpers on the v1.0 board are now completely made with solder, no cutting of traces between pads is necessary like on older versions.

Back of Mayfly Data Logger v1.0

SJ1:  Connects the RTC Square-Wave Interrupt line to pin A7 (default) or D10. This allows the RTC to wake up the Mayfly from sleep mode. Default position is connected to A7.  Remove the solder bridge to free up pin A7 for something else. Add solder bridge to connect center pad to D10 if you’d like to use the RTC square wave on the D10 hardware interrupt.

SJ2:  Connects the user pushbutton to pin D21.  Default position is ON.  Remove the solder to free up D21.

SJ3:  Enables the red LED (LED3) to be lit when the switched power 3.3v/5v/12v lines are turned on.  Default position is ON.  Remove the solder to disable the LED.

SJ4:  Enables the yellow LED (LED4) that is lit whenever the lipo battery is being charged.  Default position is ON.  Remove the solder to disable the LED.

SJ7:  Connects the Bee socket Ring Indicator to A3.  Default position is OPEN.

SJ8:  Connects the Bee socket TX signal to Mayfly TXD0 (UART 0) or TXD1 (UART 1).  Default position is TXD1

SJ9:  Connects the Bee socket RX signal to Mayfly RXD0 (UART 0) or RXD1 (UART 1).  Default position is RXD1

SJ12:  This jumper allows you to easily connect the onboard 1M-ohm pullup resistor to D10.  Default position is OFF. Add a solder bridge if you want to connect D10 to the onboard pullup resistor.  This is handy for using D10 as a hardware interrupt.  DO NOT use this jumper if you have modified SJ1 to use D10 as the RTC interrupt.  Also, DO NOT use this jumper if you are using D10 for any other type of input besides something that needs the pullup.

SJ14:  Charge/power controller input current limit:  500ma or 1A (default).  This jumper allows you to select the maximum current the Mayfly will draw from the USB or battery source.  Default setting is 1 amp (solder jumper closed).  Remove the solder bridge if you want to decrease the current limit to 500mA.  Note that most computer USB ports are limited to providing 500mA so use caution if you leave this in the 1A setting and and attempt to draw more than 500ma from a USB source.

SJ15:  Lipo battery charge rate:  500mA (default) or 1A.  This jumper allows you to select the maximum charger output current of the onboard Lipo charger.  Default setting is 500mA (solder jumper open).  Add a solder bridge to increase the rate to 1A.  Note that you’ll also need to close jumper SJ14 (set input limit to 1A) in order to get 1A charger output.  This setting should only be changed if your input power source can supply more than 500mA.  Setting the rate to 1A also causes the bq24074 charger chip to get extremely hot during charging, so use caution.

SJ16:  Bee power LED enable.  Enables the white LED (LED7) that is lit whenever the Bee power pin is active.  Default jumper position is OFF.  Add solder to enable the LED.

SJ17:  Bee network status LED enable.  Enables the blue LED (LED10) that is lit to show Bee module network status (if available).  Default jumper position is OFF.  Add solder to enable the LED.  (only for use with certain Bee modules that offer status output on Bee pin 15, like the Digi Xbee boards)

SJ18:  Bee regulator control: D18 (default) or 3.3v.  Allows you to control the bee socket power by using D18 (default) or connect to constant 3.3v power.

SJ19:  Mayfly pin D19 to Bee pin 12 (default) or 13.  This jumper is used to select which Bee board status pin gets connected to Mayfly pin D19.  For Digi brand Xbee boards, change this jumper to 13.  But for most other modules (like EnviroDIY LTE cell boards), leave this jumper at default pin 12 setting.

SJ20:  Mayfly A5 to Bee Reset (default) or Bee RTS.  This jumper allows you to select whether Mayfly pin A5 connects to Bee pin 5 for Bee Reset (default) or to Bee pin 16 for Bee RTS.

SJ21:  Bee Reset pullup enable.  Default position is CLOSED.  Remove solder jumper if your bee module needs Bee pin 5 to not be pulled high.

SJ22:  SHT40 Humidity/Temp sensor enable.  Allows you to remove power from the onboard SHT40 Humidity/Temp sensor.  Default position is CLOSED. Remove solder jumper to disable sensor.

SJ23:  Analog light sensor enable.  Allows you to remove power from the onboard Analog Light Sensor.  Default position is CLOSED. Remove solder jumper to disable sensor (also remove SJ24).

SJ24:  Analog light sensor to pin A4.  This jumper connects the analog light sensor output to Mayfly analog pin A4.  Default position is CLOSED.  Remove solder jumper to disconnect light sensor and free up pin A4.

SJ25:  Boost regulator output voltage selection:  12v (default) or 9v.  This jumper allows you to change the output of the usual “Switched 12 volts” output to “Switched 9 volts”.  This is useful if you have a sensor that requires 9v but could be damaged by powering it at 12v.  Note that all of the Grove jack power jumpers labeled 12v will then be changed to 9v, as well as the 12vSW pins in the 2×10 headers will also become 9v-Switched.

Mayfly v0.5b

On the back of the Mayfly v0.5b board (boards made between 2016 and 2020), there are 12 user-configurable solder jumpers

SJ1:  Connects the RTC Square-Wave Interrupt line to pin A7 (or D10 on board v0.4). This allows the RTC to wake up the Mayfly from sleep mode. Default position is connected to A7.  Cut the trace to free up pin A7 for something else. Add solder bridge to connect center pad to D10 if you’d like to use the D10 hardware interrupt.

SJ2:  Connects the pushbutton to pin D21.  Default position is ON.  Cut the trace to free up D21.

SJ3:  Enables the red LED to be lit when the switched 3.3v line is turned on.  Default position is ON.  Cut the trace to disable the LED.

SJ4:  Enables the yellow LED that is lit whenever the lipo battery is being charged.  Default position is ON.  Cut the trace to disable the LED.

SJ5:  Enables the 5v boost circuitry.  Default position is ENABLED.  Cut the trace and solder the middle pad to the DISABLE pad to deactivate the 5v boost circuit.  Note:  This jumper has been removed on board version 0.5 and later

SJ6:  Connects the RTC Reset or 32khz signal to pin D18.  Default position is NONE.  Solder the middle pad to only one other pad if needed.
Note:  SJ6 and SJ10 are both used for configuring inputs to D18.  Do not use SJ10 if you select a setting for SJ6.

SJ7:  Connects the Bee socket Ring Indicator or Associate lines to A5.  Default position is NONE.

SJ8:  Connects the Bee socket TX signal to Mayfly TXD0 (UART 0) or TXD1 (UART 1).  Default position is TXD1

SJ9:  Connects the Bee socket RX signal to Mayfly RXD0 (UART 0) or RXD1 (UART 1).  Default position is RXD1

SJ10:  Connects the microSD socket’s Card Detect line to D18.  Default position is OFF.  Solder this jumper together if you want to be able to sense a memory card in either the horizontal socket or the vertical adapter board.
Note:  SJ6 and SJ10 are both used for configuring inputs to D18.  Do not use SJ6 if you select a setting for SJ10.

SJ11:  Controls power to the FT232RL USB chip.  Default position is ON.  Cut this trace if you do not want to use the USB port for programming.

SJ12:  Only on board v0.5 and later, this jumper allows you to easily connect the onboard 1M-ohm pullup resistor to D10.  Default position is OFF. Add a solder bridge if you want to connect D10 to the onboard pullup resistor.  This is handy for using D10 as a hardware interrupt.  DO NOT use this jumper if you have modified SJ1 to use D10 as the RTC interrupt.  Also, DO NOT use this jumper if you are using D10 for any other type of input besides something that needs the pullup.

SJ13:  Only on board v0.5b and later, this jumper allows you to select the power source for the Bee socket’s Vcc pin (Bee pin 1). The default setting is that Bee is powered by the Mayfly’s main 3.3v Vcc supply.  By cutting the SJ13 trace and soldering the middle pad to the LiPo setting, you can connect the Bee Vcc pin directly to the Mayfly’s LiPo battery input.

On the front of the board, there are 4 small 3-pin headers next to the Grove connectors.  These headers allow you to select what voltage signal goes on the V line of the Grove connector.

The 2 Grove connectors labeled “I2C” and “D4-5” can be powered by either 3.3v constantly or the switchable 3.3v signal (controlled by D22).

The 2 Grove connectors labeled “D6-7” and “D10-11”  can be powered by either the switchable 3.3v line or the switchable 5v line (both controlled by D22)

The 2 Grove connectors for the Auxiliary Analog converter can be powered by either the switchable 3.3v line or the switchable 5v line (both controlled by D22)

These are 2.0mm pitch jumpers, so a standard 0.1-inch jumper will not fit securely.