3-72 Theory of Operation: Bluetooth
The Bluetooth IC shutdown (U2415 pin L3) and wakeup (U2415 pin K3) pins are also connected to
the host controller. A Bluetooth PTT pin on the host controller (U2415 pin J2) tells the OMAP (U6302
pin Y5) when the user pressed the PTT button on the Bluetooth accessory. As the BT IC I/O is 1.8V,
but the host controller I/O is 3.3V, level shifters are employed for interconnection between the two.
The host processor IC is connected to the LF receiver IC by a four-wire SPI bus. This SPI bus also
communicates with an on-board accelerometer. The LF transmitter circuit uses a 125 kHz signal
(U2415 pin M3) that is turned on and off (OOK) by the USART1_TX signal (U2415 pin L12).
The host processor is connected to the 3.3V SDRAM using a synchronous interface. The host
processor is connected to the OMAP on the vocon by a full-speed USB (D11 & D12). VBus is a
sense line only.
Table 3-17. SPI I/O
Signal Name Pad Name GPIO MUX
Function
Expansion Board
Schematic Name
I/O
SPIP – NPCS[2] PA09 9 B SPIO_CS2 O
SPIP – NPCS[0] PA10 10 A NFC_CS O
SPIP – MISO PA11 11 A SPIO_MISO I
SPIP – MOSI PA12 12 A SPIO_MOSI O
SPIP – SCK PA13 13 A SPIO_CLK O
Table 3-18. USB I/O
Signal Name Pin Name Pad Name Expansion Board
Schematic Name
I/O
GPIO19 C12 PA19 USB_BOOT_3.3V I
GPIO20 D10 PA20 ATMEL_BOOT I
DP D11 – BT_AVR_USB_DP I/O
DM D12 – BT_AVR_USB_DM I/O
VBUS E12 – BT_AVR_VBUS I
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