Rainbow Electronics AT86RF231 - Manual (Page 154)

154
8111A–AVR–05/08
AT86RF231
11.8 Dynamic Frame Buffer Protection
11.8.1 Overview
The AT86RF231 continues the reception of incoming frames as long as it is in any receive state.
When a frame was successfully received and stored into the Frame Buffer, the following frame
will overwrite the Frame Buffer content again.
To relax the timing requirements for a Frame Buffer read access the Dynamic Frame Buffer Pro-
tection prevents that a new valid frame passes to the Frame Buffer until a Frame Buffer read
access has ended (indicated by /SEL = H, refer to
Section 6.2 “SPI Protocol” on page 19 ).
A received frame is automatically protected against overwriting:
• in Basic Operating Mode, if its FCS is valid
• in Extended Operating Mode, if an IRQ_3 (TRX_END) is generated
The Dynamic Frame Buffer Protection is enabled, if register bit RX_SAFE_MODE (register
0x0C, TRX_CTRL_2) is set and the transceiver state is RX_ON or RX_AACK_ON.
Note that Dynamic Frame Buffer Protection only prevents write accesses from the air interface -
not from the SPI interface. A Frame Buffer or SRAM write access may still modify the Frame
Buffer content.
11.8.2 Register Description
Register 0x0C (TRX_CTRL_2):
The TRX_CTRL_2 register is a multi purpose register to control various settings of the radio
transceiver.
• Bit 7 - RX_SAFE_MODE
If this bit is set Dynamic Frame Buffer Protection is enabled:
Note: 1. Dynamic Frame Buffer Protection is released with the rising edge of pin23 (/SEL) of a Frame
Buffer read access, see Section 6.2.2 “Frame Buffer Access Mode” on page 20 , or radio trans-
ceiver state changing from RX_ON or RX_AACK_ON to another state.
This operation mode is independent of the setting of register bits RX_PDT_LEVEL, refer to Sec-
tion 9.1.3 “Configuration” on page 102 .
• Bit [6:2] - Reserved
Bit 7 6 5 4 3 2 1 0
+0x0C RX_SAFE_MODE Reserved OQPSK_DATA_RATE TRX_CTRL_2
Read/Write R/W R R R R R R/W R/W
Reset Value 0 0 1 0 0 0 0 0
Table 11-17. Dynamic Frame Buffer Protection Mode
Register Bit Value Description
RX_SAFE_MODE (1) 0 Disable Dynamic Frame Buffer Protection
1 Enable Dynamic Frame Buffer Protection