Rainbow Electronics AT86RF401 - Manual (Page 38)

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AT86RF401
1424D–RKE–09/02
• Bit[2]: Flag2
In transmit mode, this flag indicates the Transmit Done condition that occurs when the
buffer is empty and the counter has counted down to “0”. In receive mode, this flag indi-
cates that an edge has occurred, and the AVR should process the count value in the
BTCR and BTCNT registers. This bit is cleared upon read, e.g., IN R16, BTCR.
• Bit[1]: Data Bit
In transmit mode, this is a one-bit buffer that the AVR writes data to and the bit timer
extracts data from. When the bit timer removes the value from this register, the Flag0 bit
is set, and if enabled, an interrupt (INT2) is generated. If the interrupt is used, the ISR
should load a new bit into the buffer. If the interrupt is not enabled, then a polling method
should be used to detect Flag0 being set. Because of overhead associated with interrupt
handling, it may be slightly faster to use polling.
In receive mode, the value in this register indicates whether the edge at the IO3 pin was
rising or falling. A “1” indicates a rising edge occurred, and a “0” indicates that a falling
edge was detected. The number of AVR clock cycles since the last edge is held in the
C[9:0] (
countval) bits (that is, unless an overflow condition has occurred).
• Bit[0]: Flag0
In transmit mode, this flag indicates the buffer is empty and the AVR should load new
data into it. In receive mode, this indicates a counter overflow condition has occurred.
The AVR should increment its software counter if this condition has occurred. This bit is
cleared upon read, e.g., IN R16, BTCR.
Watchdog Timer Control Register – WDTCR
• Bits[7:5]
Reserved. These bits will always read as “0”.
• Bit[4]: WDTOE, Watchdog Turn-off Enable
This bit must be set (“1”) when the WDE bit is cleared. Otherwise, the watchdog will not
be disabled. Once set, hardware will clear this bit to “0” after four clock cycles. Refer to
the description of the WDE bit for a watchdog disable procedure.
• Bit[3]: WDE, Watchdog Enable
When the WDE is set (“1”), the Watchdog Timer is enabled, and if the WDE is cleared
(“0”), the Watchdog Timer function is disabled. WDE can only be cleared if the WDTOE
Mode[1:0] Flag2 Function
00 Disabled
01
Indicates Transmit Done condition; buffer is empty and the
counter has expired.
10 An edge has been detected at the IO3 pin.
11
Indicates Transmit Done condition; buffer is empty and the
counter has expired.
Bit 7 6 5 4 3 2 1 0
$22 – – – WDTOE WDE WDP2 WDP1 WDP0 WDTCR
Read/Write R R R R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0