2 frame transmit procedure – Rainbow Electronics AT86RF231 User Manual
Page 127
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8111A–AVR–05/08
AT86RF231
10.2
Frame Transmit Procedure
A frame transmission comprises of two actions, a Frame Buffer write access and the transmis-
sion of the Frame Buffer content. Both actions can be run in parallel if required by critical
protocol timing.
illustrates the frame transmit procedure, when writing and transmitting
the frame consecutively. After a Frame Buffer write access, the frame transmission is initiated by
asserting pin 11 (SLP_TR) or writing command TX_START to register 0x02 (TRX_STATE),
while the radio transceiver is in state PLL_ON or TX_ARET_ON. The completion of the transac-
tion is indicated by interrupt IRQ_3 (TRX_END).
Figure 10-2. Transaction between AT86RF231 and Microcontroller during Transmit
Alternatively a frame transmission can be started first, followed by the Frame Buffer write access
(PSDU data); refer to
. This is applicable for time critical applications.
Initiating a transmission, either by asserting pin 11 (SLP_TR) or command TX_START to regis-
ter bits TRX_CMD (register 0x02, TRX_STATE), the radio transceiver starts transmitting the
SHR, which is internally generated.
This first phase requires 16 µs for PLL settling and 160 µs for SHR transmission. The PHR must
be available in the Frame Buffer before this time elapses. Furthermore the SPI data rate must be
higher than the PHY data rate selected by register bits OQPSK_DATA_RATE (register 0x0C,
TRX_CTRL_2) to ensure that no Frame Buffer under run occurs, indicated by IRQ_6 (TRX_UR),
refer to
Section 11.3 “High Data Rate Modes” on page 137
.
Figure 10-3. Time Optimized Frame Transmit Procedure
AT
86RF
231
Mi
croc
on
tr
o
lle
r
Write frame data (Frame Buffer access)
Write TRX_CMD = TX_START, or assert pin 11 (SLP_TR)
IRQ_3 (TRX_END) issued
Read IRQ_STATUS register, pin 24 (IRQ) deasserted
IRQ_3 (TRX_END) issued
Write frame data (Frame Buffer access)
Write TRX_CMD = TX_START, or assert pin 11 (SLP_TR)
AT
86RF
231
Mi
c
ro
c
on
trolle
r
Read IRQ_STATUS register, pin 24 (IRQ) deasserted