BCM4390DKWBGT Datasheet, PDF (25/78 Pages) Cypress Semiconductor – WICED™ Wi-Fi IEEE 802.11 b/g/n SoC with Embedded Application Processor

BCM4390 Advance Data Sheet
SPI Flash Interface
SPI Flash Interface
The BCM4390 provides a dedicated SPI interface that connects to an external serial flash with a maximum clock
speed of 24 MHz. Use of the SPI flash interface is mandatory for self-hosted systems booting an application that
runs on the Application processor.
SPI Master/Slave Interface
In addition to the SPI flash interface the BCM4390 supports a secondary SPI interface with a clock frequency
of up to 24 MHz to support external SPI peripherals. This interface can be configured either as a master or a
slave interface. The SPI interface has various configuration options including support for active-low or active-
high operation for the chip-select, active-low or active-high operation for the interrupt line and bit ordering on
the MISO/MOSI lines to be either big endian or little endian.
UART Interfaces
UART1 and UART2 have standard 4-wire interfaces (RX, TX, RTS, and CTS) with adjustable baud rates from 9600
bps to 4.0 Mbps.
UART1 has a 1040-byte receive FIFO and a 1040-byte transmit FIFO to support high data throughput. UART2
has a smaller FIFO that is only 256-bytes. Access to the FIFOs is available to the application processor through
the AHB interface and supports either DMA or CPU driven data transfer.
The BCM4390 UART can perform XON/XOFF flow control and includes hardware support for the Serial Line
Input Protocol (SLIP). It can also perform wake-on activity. For example, activity on the RX or CTS inputs can
wake the chip from a sleep state.
The BCM4390 UARTs can operate correctly with other devices as long as the combined baud rate error of the
two devices is within ±2%.
Desired Rate
4000000
3692000
3000000
2000000
1500000
1444444
921600
460800
230400
115200
Table 5: Example of Common Baud Rates
Actual Rate
4000000
3692308
3000000
2000000
1500000
1454544
923077
461538
230796
115385
Error (%)
0.00
0.01
0.00
0.00
0.00
0.70
0.16
0.16
0.17
0.16
BROADCOM ®
February 5, 2014 • 4390-DS103-R
WICED Wi-Fi IEEE 802.11 SoC w/Embedded App Processor
Page 24
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