CYW920706WCDEVAL Hardware User Guide Doc. No.: 002-16535 Rev. **
16
7 CYW20706 Interfaces
The package CYW20706 is available in may have fewer GPIOs than the die. Some of these GPIOs are fixed function IOs
while others are reconfigurable for different interfaces. To accommodate its various applications, interface selection is
accomplished through a combination of signal routing to CYW20706 and programming using the WICED API described in later
sections.
CYW20706 interfaces are presented as two interface sets: fixed and selectable. The fixed interfaces are those with dedicated
pins and, thus, are always available. The selectable interfaces are those that a board designer chooses to use from a superset
of possible interfaces that CYW20706 supports.
See Section
” for more information on the fixed interfaces. See Section
” for
more information on the set of interfaces from which board designers can choose.
7.1 Fixed Interfaces
shows the fixed straps and digital I/O interfaces of CYW20706. In contrast to the
, the fixed
interfaces of CYW20706 have dedicated pins.
Strap or Interface Purpose
Signals
Pins
Notes
XTAL frequency selection
BT_XTAL_STRAP_0
G3
F2
G3
XTAL
0
0
40 MHz
0
1
24 MHz
1
0
20 MHz
1
1
Read from
NV memory
BT_XTAL_STRAP_1
F2
Device reset
RST_N
A6
Active LOW reset input
OTP usage
BT_OTP_3P3V_ON
G2
Pull HIGH if OTP is used; otherwise, pull LOW.
HCI UART
BT_UART_RXD
F5
HCI UART receive data (or SWDIO, see
BT_UART_TXD
F4
HCI UART transmit data (or SWDCLK, see
BT_UART_RTS_N
F3
HCI UART request-to-send input
BT_UART_CTS_N
G4
HCI UART clear-to-send input
Serial Peripheral Interface (SPI) or I
2
C, sometimes known as
Broadcom Serial Control (BSC)
SPI2_MISO_I2C_SCL
D8
SPI MISO
SPI2_MOSI_I2C_SDA
SPI MOSI
SPI2_CLK
E7
SPI clock output
SPI2_CSN
D7
SPI active LOW chip select output
Table 7-1. Fixed Straps and Digital I/O Interfaces
1
Use the SPI2 interface for applications where the CYW20706 firmware image is to be loaded from onboard serial flash. The SPI2
interface is sometimes referred to as Spiffy2.
2
Although the SPI2_MISO_I2C_SCL and SPI2_MOSI_I2C_SDA signal names imply support for an I
2
C-compatible interface via pins D8
and E8, an I2C-compatible interface is not usable via these pins since the SPI signals are connected to the serial flash on this hardware.
CYW20706 does support an I
2
C-compatible interface (BSC interface) via pins A8 and C7 (including pull ups) or B7 and C7 (see Section
”).
