Rx State Timing; Received-Frame Processing; Single Received Frame And Transmitted Acknowledgment Frame - Texas Instruments CC253x User Manual

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– Sets RXENABLE[7]
– Aborts ongoing transmission or reception by forcing a transition to RX calibration.
• The STXON strobe, when FRMCTRL1.SET_RXENMASK_ON_TX is enabled:
– Sets RXENABLE[6]
– The receiver is enabled after transmission completes.
• Setting RXENABLE != 0x00 by writing to RXENMASKOR:
– Does not abort ongoing transmission or reception.
The receiver is turned off by the following actions:
• The SRFOFF strobe:
– Clears RXENABLE[7:0]
– Aborts ongoing transmission or reception by forcing the transition to IDLE mode.
• Setting RXENABLE = 0x00 by writing to RXENMASKAND
– Does not abort ongoing transmission or reception. Once the ongoing transmission or reception is
finished, the radio returns to the IDLE state.
There are several ways to manipulate the RXENABLE registers:
• The SRXMASKBITSET and SRXMASKBITCLR strobes (affecting RXENABLE[5])
• The SRXON, SRFOFF and STXON strobes, including the FRMCTRL1.SET_RXMASK_ON_TX setting

23.9.2 RX State Timing

The receiver is ready 192 μs after RX has been enabled by one of the methods described in
Section 23.9.1. This is referred to as RX turnaround time in [1].
When returning to receive mode after frame reception, there is by default an interval of 192 μs where SFD
detection is disabled. This interval can be disabled by clearing FSMCTRL.RX2RX_TIME_OFF.

23.9.3 Received-Frame Processing

The radio integrates critical portions of the RX requirements in IEEE 802.15.4-2003 and -2006 in
hardware. This reduces the CPU interruption rate, simplifies the software that handles frame reception,
and provides the results with minimum latency.
During reception of a single frame, the following frame-processing steps are performed:
Preamble SFD LEN
(1)
(1) Detection and removal of the received PHY synchronization header (preamble and SFD), and reception of
the number of bytes specified by the frame-length field.
(2) Frame filtering as specified by [1], section 7.5.6.2, third filtering level.
(3) Matching of the source address against a table containing up to 24 short addresses or 12 extended IEEE
addresses. The source address table is stored in the radio RAM.
(4) Automatic FCS checking, and attaching this result and other status values (RSSI, correlation, and source-
match result) to received frames.
(5) Automatic acknowledgment transmission with correct timing, and correct setting of the frame-pending bit,
based on the results from source address matching and FCS checking.
Figure 23-10. Single Received Frame and Transmitted Acknowledgment Frame
SWRU191F – April 2009 – Revised April 2014
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Received Frame
MAC Payload
MHR
(2) (3)
Copyright © 2009–2014, Texas Instruments Incorporated
Transmitted Acknowledgment Frame
FCS Preamble
(4)
Receive Mode
SFD LEN MHR FCS
(5)
M0110-02
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CC253x Radio