PRELIMINARY
CYW43438
12.4 External Coexistence Interface
The CYW43438 supports a 2-wire coexistence interface to enable signaling between the device and an external colocated wireless
device in order to manage wireless medium sharing for optimal performance. The external colocated device can be any of the following
ICs: GPS, WiMAX, LTE, or UWB. An LTE IC is used in this section for illustration.
Figure 31 shows a 2-wire LTE coexistence example. The following definitions apply to the GPIOs in the figure:
■ GPIO_1: WLAN_SECI_TX output to an LTE IC.
■ GPIO_2: WLAN_SECI_RX input from an LTE IC.
Figure 31. 2-Wire Coexistence Interface to an LTE IC
GPIO_1
GPIO_2
WLAN_SECI_TX
WLAN_SECI_RX
UART_IN
WLAN
BT/FM
UART_OUT
Coexistence
Interface
CYW43438
LTE/IC
Notes:
OR’ing to generate ISM_RX_PRIORITY for ERCX_TXCONF or BT_RX_PRIORITY is achieved by
setting the GPIO mask registers appropriately.
WLAN_SECI_OUT and WLAN_SECI_IN are multiplexed on the GPIOs.
See Figure 27 and Table 14: “UART Timing Specifications” for UART timing.
12.5 JTAG Interface
The CYW43438 supports the IEEE 1149.1 JTAG boundary scan standard over SDIO for performing device package and PCB
assembly testing during manufacturing. In addition, the JTAG interface allows Broadcom to assist customers by using proprietary
debug and characterization test tools during board bring-up. Therefore, it is highly recommended to provide access to the JTAG pins
by means of test points or a header on all PCB designs.
12.6 UART Interface
One UART interface can be enabled by software as an alternate function on the JTAG pins. UART_RX is available on the JTAG_TDI
pin, and UART_TX is available on the JTAG_TDO pin.
The UART is primarily for debugging during development. By adding an external RS-232 transceiver, this UART enables the
CYW43438 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 it provides a FIFO size of 64 × 8 in each direction.
Document Number: 002-14796 Rev. *K
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