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UM-B-077
DA14681 Wearable Development Kit Hardware Manual
User Manual
Revision 1.2
06-Apr-2017
CFR0012
34 of 47
© 2017 Dialog Semiconductor
Figure 29: Block Diagram of the Host Communication Mode Implementation
The NFC module can be activated in Host Communication mode by raising ENVDDSE, providing a
clock at the corresponding line and raising the RST line. Here, a 4 MHz clock is provided by the
DA14681. Upon powering up and entering host mode successfully, the NFC module will output an
Answer to Reset (ATR) message, after which protocol parameter negotiation and communication
with the host can be initiated.
Figure 30: Voltage Levels of the NFC Module Pins
– Host Communication Mode
In order to power up the NFC module in RF Communication (card emulation) mode, only power
needs to be applied while the IO and RST lines are high impedance and the CLK and ENVDDSE
signals are driven low.
DA14681 SoC
LA66002 NFC
FXL6408
I/O expander
I2C
P4_0
P4_3
ENVDDSE
VDDSE
IO
CLK
VCC
RESET
3.3V LDO
EN
P3_5
P3_7