RX95HF Datasheet, PDF (21/44 Pages) STMicroelectronics – Near field communication transceiver for tag emulation

RX95HF
Commands
5.8.1
5.8.2
5.8.3
Direction
RX95HF to
Host
Table 17. IDLE command description (continued)
Data
Comments
Example
0x82
0x00
Error code
Length of data
<<<0x8200 Invalid command
length
Idle command parameters
The Idle command (Host to RX95HF) has the following structure (all values are
hexadecimal):
07
Command
code
Table 18. Idle command structure
0E
xx
yy zz
yy zz
yy zz
Data length WU source Enter Control WU Control Leave Control
Table 19. Summary of Idle command parameters
Parameter
Description
Command code
Data length
This byte is the command code. ‘07’ represents the Idle command. This
command switches the device from Active mode to WFE mode.
This byte is the length of the command in bytes. Its value depends on the
following parameter values.
WU Source
Enter Control
WU Control
This byte defines the authorized wake-up sources in the Wake-up source
register. Predefined values are:
0x04: Field Detector0x08: Low pulse on IRQ_IN
These two bytes (EnterCtrlL and EnterCtrlH) define the resources when
entering WFE mode.
0x0400: Hibernate0x0142: Sleep (if Field Detector source is enabled)
These two bytes (WuCtrlL and WuCtrlH) define the wake-up resources.
0x0400: Hibernate
0x3800: Sleep
Leave Control
These two bytes (LeaveCtrlL and LeaveCtrlH) define the resources when
returning to Ready state.
0x1800: Hibernate
0x1800: Sleep
Optimizing wake-up conditions
Using the Wake-up source register, it is possible to cumulate sources for a wake-up event. It
is strongly recommended to always set an external event as a possible wake-up source.
To cumulate wake-up sources, simply set the corresponding bits in the Wake-up source
register. For example, to enable a wake-up when an RF field is detected (bit 1 set to ‘1’) or
on a low pulse on pin IRQ_IN (bit 3 set to ‘1’), set the register to 0x0A.
Using various techniques to return to Ready state
The Idle command and reply set offers several benefits to users by enabling various
methods to return the RX95HF to Ready state. Some methods are nearly automatic, such
as waiting for a timer overflow or a field detection, but others consume more power
compared to the ones requesting a host action. A description of each method follows below.
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