Product Overview

5V: 5V is supplied to the TinyDuino system by either the USB TinyShield or the Power TinyShield. The USB TinyShield includes a power switch that will disconnect the 5V USB
power from the TinyDuino 5V signal, if it detects that VIN is present. At that point the Power TinyShield will be supply the 5V signal
3V3: 3V3 is a legacy signal from the standard Arduino system, and is not used by the TinyDuino. It is currently not connected to any power supply and cannot be used to supply
power to external sensors (use VCC instead)
VBATT: VBATT is the battery voltage for the TinyDuino system, or alternatively some external voltage between 2.7V and 5.5V. If a coin cell battery is attached to the TinyDuino
processor board, this is directly connected to VBATT. The same is true is a Li-Ion battery is attached to the TinyDuino processor board
VCC: VCC is the main power supply for the microcontroller and all of the TinyShields. If you are connecting any external sensors or boards, you should use VCC as your power
supply.
VCC Power Switching
The main TinyDuino processor board includes power switching circuitry to control what is connected to VCC. This can be connected to either VBATT or 5V depending
on what voltages are present in the system. If 5V is present (such as the USB TinyShield is plugged in), VCC will be connected to 5V. If 5V is not present but a battery
is connected to VBATT, then VBATT will be connected to VCC. If both 5V and VBATT are present, 5V will be used, and VBATT will be completely disconnected (except
for the case where a Li-Ion battery charger TinySheid is connected, in which case the 5V will be used to recharge the battery).
TinyShield Power
All TinyShields are designed to operate over the entire TinyDuino voltage range (2.7V - 5.5V) unless specifically mentioned in the technical details for that TinyShield.
Where needed, TinyShields have local power supplies and level converters to safely allow the entire voltage range).
TINYS H I E L D C O M PAT I B I L I T Y
Since the TinyShields use pins from the TinyDuino, in some cases there will be conflicts when two TinyShields that use the same pins are in the same TinyDuino stack. This
matrix below shows which TinyShields can be used with others at the same time. You can download the full pin listing and compatibility matrix as an excel spreadsheet here.