Rainbow Electronics AT86RF230 - Manual (Page 29)

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AT86RF230
5131A-ZIGB-06/14/06
CLKM
SEL
SCLK
MOSI
MISO
IRQ
SLP_TR
COMMAND FRAME LENGTH FRAME DATA 1 FRAME DATA 2 FRAME DATA 3 FRAME DATA n
XX XX XX XX XX XX
Frame_download
Transmit Start
Figure 7-11. Frame Transmit Sequence (SLP_TR Assertion Starts Transmission)
7.6. Sleep/Wake-up and Transmit Signal
The SLP_TR signal is a multi-functional pin. It can be used as transmit start or as a sleep signal. The function of
the pin depends on the transceiver status.
Transceiver Status Pin Function Description
TRX_OFF Sleep Forces the transceiver into SLEEP mode
RX_ON Disable CLKM Forces the transceiver into RX_ON_NOCLOCK state and disables CLKM
PLL_ON TX start Start frame transmission
TX_ARET_ON TX start Start of frame retry
RX_AACK_ON TX start Start of frame acknowledge
Table 7-2. SLP_TR Multi-functional Pin States
The pin has no function if the transceiver is in other modes.
If used as a sleep signal, releasing the pin SLP_TR = 0 forces the transceiver into TRX_OFF mode and enables
the main clock. If used as a transmit start signal, the low-to-high edge starts the transmission of a frame stored in
the frame buffer.
From the application point of view, there are two possible power-down scenarios supported by the AT86RF230.
Either both the controller and the AT86RF230 are powered down, or the AT86RF230 listens for an incoming frame
and only the controller is powered down.
The first power-down scenario is shown in Figure 7-12. The controller forces the AT86RF230 to SLEEP mode by
setting SLP_TR to “1” when the transceiver is in TRX_OFF mode. The main clock at pin CLKM will be switched off
after 35 clock cycles. This enables the controller to complete its power-down routine and prevent dead-lock
situations. The AT86RF230 will awaken when the controller releases the pin SLP_TR. This concept provides the
lowest possible power consumption.
If an incoming frame is expected and no other application is running on the controller, the controller itself can be
powered down without the risk of missing an incoming frame. This scenario is shown in Figure 7-13. In RX_ON
state, the CLKM pin will switched off after 35 clock cycles when the pin SLP_TR is set to “1”. The start of a frame
reception will be signaled by an RX_START IRQ and the clock will be switched on again.