Due to an issue inside the STM32F4 MCU, the JTAG connection will no longer work when GPIO PB4 is used. This is not an problem when using the Lua Development Environment, but can introduce issues when custom Screvle firmware is developed. Alternatively, if PB4 needs to be used, the Serial Wire Debug (SWD) interface can be used instead of JTAG.
All except the following pins are 5V tolerant: PA4, PA5 (the pins supporting the DAC peripheral).
Enabled by default, current is limited to 500mA by a poly-fuse.
Disabled by default, current is limited to 500mA by a poly fuse. To enable the 5V output, call the system.enable5V() function:
-- Turn on 5V output system.enable5V()
Li-Ion Battery Output
The output of the Li-Ion battery charger is available to derive other voltages. The nominal voltage of this pin is 4.35V when externally powered, or the Li-Ion battery voltage when not externally powered.
Coin-Cell Battery Output
Output of the Reatl-Time-Clock backup battery. Should only be used for (low-) power backup.
Allows powering Screvle via the expansion header. Supply 5V power.