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8111C–MCU Wireless–09/09
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.
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
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 s for PLL settling and 160 s 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),
Figure 10-3. Time Optimized Frame Transmit Procedure
AT
86RF
231
Mi
croc
on
tr
oll
er
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
cr
o
con
trolle
r
Read IRQ_STATUS register, pin 24 (IRQ) deasserted