tea5766uk NXP Semiconductors, tea5766uk Datasheet - Page 14

• Manufacturer Part Number: tea5766uk
• Description: Tea5766uk Stereo Fm Radio + Rds
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA5766UK_1
Product data sheet
7.21.1 Muting during RDS update
The tuner can do an RDS update. This is a preset, but with a 2 ms IF count time. The
tuner will jump to the alternative frequency and check the level and the IF count using a
2 ms count time. When RSSI level check is above the specified level and the IF count
result is within the limits then the tuner will stay at the alternative frequency and stay
muted. The host processor can now decide what to do. If the alternative frequency is not
valid it will jump back to the frequency it came from. The algorithm will finish with the
FRRFLAG being set and generate an interrupt. After this interrupt the TEA5766UK will not
measure the IF count for a period of 15.6 ms. 15.6 ms after completing an RDS jump a
measurement of the IF count will start and hence the IF count result and the IFFLAG will
be updated 31.25 ms after completing the algorithm. The level measurement will start
15.6 ms after the tuning algorithm, so bit LEVFLAG and the RSSI information will be
updated 15.6 ms after the algorithm. The state of the TEA5766UK can be checked by
reading registers: INTFLAG, FRQCHK, IFCHK and LEVCHK.
states after an RDS update and
An RDS update (AF jump) is always muted. There are two states after the algorithm has
stopped:
Table 6.
[1]
Bit
IFFLAG
0
0
0
0
1
1
1
1
1. The tuner jumps to an alternative frequency which is not valid (according to the
2. The tuner jumps to a valid alternative frequency and stays there. Now it remains in
specified SSL limit and fixed IF counter limits) and jumps back, then it will get not
muted automatically.
mute. The host processor can switch to not muted or it keeps the tuner muted and can
check for the presence of RDS data. The recommended method to get not muted is to
do a preset to the current frequency (at a preset an IF count time of 15.6 ms is used,
which gives a more accurate IF count result than the result obtained by the AF jump,
where 2 ms is used).
This table is valid until 31.25 ms after an RDS update has completed. It shows the outcome of the flag
register when a read is done after INTX has gone LOW with the condition that no other mask bits are set
than shown in the table.
RDS update truth table
BLFLAG
0
0
1
1
0
0
1
1
Rev. 01 — 22 March 2007
FRRFLAG
0
1
0
1
0
1
0
1
Figure 5
[1]
Comment
this cannot occur if INTX has gone LOW and only IFMSK,
FRRMSK and BLMSK were set
alternative frequency jump successful; radio is tuned to the
alternative frequency and keeps muted
not a valid state
not a valid state
not a valid state
AF jump has been done, but the wanted channel fails the IF
count, the PLL will be set back to the old value
not a valid state
this cannot occur if INTX has gone LOW and only IFMSK,
FRRMSK and BLMSK were set
shows the flowchart.
Table 6
TEA5766UK
Stereo FM radio + RDS
shows the possible
© NXP B.V. 2007. All rights reserved.
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