BCM88335 Data Sheet
GPIO Interface
GPIO Interface
The following number of general-purpose I/O (GPIO) pins are available on the WLAN section of the BCM88335
that can be used to connect to various external devices:
•
WLBGA package – 9 GPIOs
Upon power up and reset, these pins become tristated. Subsequently, they can be programmed to be either
input or output pins via the GPIO control register. In addition, the GPIO pins can be assigned to various other
functions (see Table 21: “BCM88335 GPIO/SDIO Alternative Signal Functions,” on page 85).
External Coexistence Interface
An external handshake interface is available to enable signaling between the device and an external co-located
wireless device, such as GPS, WiMAX, LTE, or UWB, to manage wireless medium sharing for optimum
performance.
Figure 17 shows the LTE coexistence interface. See Table 21: “BCM88335 GPIO/SDIO Alternative Signal
Functions,” on page 85 for details on multiplexed signals such as the GPIO pins.
See Table 9: “Example of Common Baud Rates,” on page 49 for UART baud rates.
Figure 17: Broadcom GCI or BT-SIG Mode LTE Coexistence Interface for the BCM88335
BCM88335
LTE\IC
SECI_OUT/BT_TXD
SECI_IN/BT_TXD
UART_IN
GCI
WLAN
BT
UART_OUT
NOTES:
SECI_OUT/BT_TXD and SECI_IN/BT_RXD are multiplexed on the GPIOs.
The 2-wire LTE coexistence interface is intended for future compatibility with the BT
SIG
2-wire interface that is being standardized for Core 4.1.
ORing to generate ISM_RX_PRIORITY for ERCX_TXCONF or BT_RX_PRIORITY is
achieved by setting the GPIO mask registers appropriately.
UART Interface
One 2-wire UART interface can be enabled by software as an alternate function on GPIO pins (see
Table 21: “BCM88335 GPIO/SDIO Alternative Signal Functions,” on page 85). Provided primarily for debugging
during development, this UART enables the BCM88335 to operate as RS-232 data termination equipment
(DTE) for exchanging and managing data with other serial devices. It is compatible with the industry standard
16550 UART, and provides a FIFO size of 64 × 8 in each direction.
Broadcom®
September 23, 2015 • 88335-DS100-R
Page 54
BROADCOM CONFIDENTIAL
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