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3.2.4
Power Domains
Figure 3.2.3 - Block Diagram
– Power Domains
All circuitry on the board is powered up when the board is run in “Line” mode on an external 5 volt supply as
shown by the grey shaded areas above. You MUST run in 5 volt mode to utilize the mbed controller or external
interfaces such as the Host UART during RF testing or FW programing.
The yellow shaded area indicates what blocks are active in either 3V Lithium battery or 1.5V AAA Alkaline battery
modes. These Battery modes support both the Sensor Demo and the Beacon demo. You cannot utilize test
modes (see Section 6) via the Host UART port while in Battery mode unless you are also hooked up to an
external 5v supply.
In 1.2v Zinc/Air battery mode, only the BT4 SoC is powered up as shown by the orange shaded area. This allows
the user to run the Beacon demo where no additional I/O is active. Unlike a production SOC, the BT4
Demonstration SoC relies on external SPI FLASH to store its firmware. This 1.8v FLASH is powered via the 1.5V
AAA battery during boot while the BT4 SoC is powered by the 1.2v Zinc/Air battery. Therefore, a 1.5V AAA battery
must be installed on the board (but 1.5 volt switch off) for Boot purposes when running in 1.2v mode. (Depending
on your board revision, the additional 1.8volt Gyro and Temperature sensors maybe active in 1.2v mode. These
sensors are also powered by the 1.5V AAA battery).
The table below shows the operational usage modes that are available in each of the 4 power source options.
Table 3.2.3 - Power Source vs. Operation Mode