DocID026906 Rev 4

11/27

SP1ML

Hardware design

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2.2

Typical application circuit

In a typical application the SP1ML module is connected to a host MCU using a standard

UART, with transmit and receive signals. This is illustrated in Figure 3.

Figure 3. Typical application circuit

Optional functionality

1.

When the TXRX_LED (S24) configuration register (see Table 10) is set to 1, the

TXRXLED signal is an active-low open drain output that can be used to drive an

external LED for status indication when data is sent or received.

2.

The MODE0 signal provides a hardware method for switching between command and

operating modes. The SHDN signal allows the module to be placed into a low power

shutdown mode and woken up again.

3.

The BOOTMODE AND RESET signals should be connected if module firmware will

need to be updated over the UART interface.

4.

To support custom module firmware, the serial wire debug signals need to be

accessible for programming and debugging.

2.3

Layout guidelines

The application PCB requires a flooded ground plane. Care must be taken to ensure there

are no traces or ground planes under the area surrounding the antenna, with the exception

SP1ML

MODULE

HOST

MCU

TXD

TXD

RXD

RXD

RTS

CTS

GPIO

GPIO

BOOTMODE

RESET

GPIO

GPIO

MODE0

SHDN

TXRXLED

1

2

3

VDD

RESET

SWCLK

SWDIO

4

SWD

HEADER

VDD

VDD

VDD

GND

10uF