NXP Semiconductors
UM11227
NTM88 family of tire pressure monitor sensors
UM11227 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 6 — 24 April 2020
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Field Description
5:0
RFFT[5:0]
RFFT[5:0] – Frame Number Timer
The 6 bits RFFT[5:0] select the interframe timing between multiple frames of transmission. The time value
is equal to a nominal one millisecond for each count of the RFFT[5:0] bits multiplied by the frame number of
the last transmitted frame. The RFFT[5:0] control bits are cleared by the RFMRST signal.
0 0 0 0 0 0 = Result of Reset
10.16.11.8 RFM control 7 register (RFCR7)
Table 117. RFM control 7 register (RFCR7) (address $1837)
Bit 7 6 5 4 3 2 1 0
R RFIF RFEF RFVF 0 RCTS 0
W — — — RFIAK
RFIEN RFLVDEN
— RFMRST
Reset ($00) 0 0 0 0 0 0 0 0
Table 118. RFCR7 register field descriptions
Field Description
7
RFIF
RFIF – RF Interrupt Flag
The read-only RFIF status bit indicates if the RF transmission has ended properly when using the data
buffer mode and the SEND bit has been cleared. Writes to this bit will be ignored. The RFIF status bit is
cleared by writing a logical one to the RFIAK bit or the RFMRST bit. RFMRST signal clears this bit.
0 = RF transmission in progress or not in the data buffer mode; Result of Reset
1 = RF transmission completed in the data buffer mode.
6
RFEF
RFEF – RF Transmission Error Flag
The read-only RFEF status bit indicates if there was an error in the current or prior RF transmission. Writes
to this bit will be ignored. The RFEF status bit is cleared by writing a logical one to the RFIAK bit or the
RFMRST bit. RFMRST signal clears this bit.
0 = No RF transmission error occurred; Result of Reset
1 = RF transmission error occurred.
5
RFVF
RFVF – RF LVD Trigger Flag
When the RF LVD is enabled and the supply voltage falls below the threshold, the read-only RFVF flag will
be set if the RFLVDEN bit is set. Writes to this bit will be ignored. The RFVF status bit is cleared by writing a
logical one to the RFIAK bit or the RFMRST bit. RFMRST signal clears this bit
0 = Voltage is and has been above RF LVD rising threshold or the RF LVD is disabled; Result of Reset
1 = Voltage has dropped below the RF LVD falling threshold since last reset of this bit.
4
RFIAK
RFIAK – RF Interrupt Acknowledge Control
Writing a one to the RFIAK bit clears the RFIF, RFEF and RFVF flag bits. Writing a zero to the RFIAK bit
has no effect on the RFIF, RFEF and RFVF flag bits. The RFMRST signal has no effect on this bit.
0 = No effect; Result of Reset
1 = Write 1 to clear the RFIF, RFEF, and RFVF bits.
3
RFIEN
RFIEN – RF Interrupt Enable Control
The RFIEN bit enables the RFIF, the RFEF and the RFVF bits to generate an interrupt to the MCU. The
RFMRST signal clears this bit.
0 = RF interrupts disabled; Result of Reset
1 = RF interrupts enabled.
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