Audio Interface Module (AIM)
MCF5253 Reference Manual, Rev. 1
Freescale Semiconductor
17-43
Upon request Freescale can supply example s/w code that implements the Frequency measurement and
controls the XTRIM output to allow CRIN to be locked to the EBU clock input.
The PLL maintaining phase relation between the incoming source signal and internal signal is mainly
digital. It is necessary, however, to measure the phase/frequency of the incoming signal in relationship with
the CRIN clock in order to be able to steer the sample rate convertor clock. The circuit shown in
is used for maintaining this phase relationship.
Figure 17-24. Frequency Measurement Circuit
Associated with the Frequency measurement block are two registers. (See
). The circuit will
measure the frequency of the incoming clock by comparison with the audio CRIN clock (which is typically
16.93 MHz or 11.2896MHz). Multiplexer
(1)
selects the incoming clock source. Registers
(2)
,
(3)
, and xor
(4)
are an edge detector. Multiplexer
(5)
is a by-pass for the IEC958 input. The rest of the circuit is a
second-order filter with a bandwidth of approximately 80 Hz. The output FreqMeas(31:0) is an unsigned
number, giving the frequency of the selected source as a function of the CRIN clock. The filter is calculated
internally in 48 bit precision. The 16 LSBs are not sent out.
The value read from the FreqMeas Register is calculated as follows:
•
For measurement of the IIS inputs: FreqMeas = (IIS SCLK Freq
×
2)/Faudio
×
(2 ** 15)
×
Gain
•
For measurement of the EBU input: FreqMeas = (EBU Freq) / Faudio
×
(2 ** 15)
×
Gain
Table 17-24. PhaseConfig and Frequency Measure Register Addresses
Address
Name
Width
Description
Access
MBAR2 + 0xA3
PhaseConfig
8
Phase Configuration (gain and source select)
R/W
MBAR2 + 0xA8
FreqMeas
32
Frequency measurement
R
xor
1
D
D
D
D
2
3
4
5
6
+
7
8
9
10
11
+
12
13
14
15
16
sat
sat
FreqMeas[31:0]
CRIN
SCLK1
SCLK2
SCLK3
EBU-In
Select
Summary of Contents for MCF5253
Page 1: ...Document Number MCF5253RM Rev 1 08 2008 MCF5253 Reference Manual...
Page 26: ...MCF5253 Reference Manual Rev 1 xxvi Freescale Semiconductor...
Page 32: ...MCF5253 Reference Manual Rev 1 xxxii Freescale Semiconductor...
Page 46: ...MCF5253 Introduction MCF5253 Reference Manual Rev 1 1 14 Freescale Semiconductor...
Page 62: ...Signal Description MCF5253 Reference Manual Rev 1 2 16 Freescale Semiconductor...
Page 98: ...Instruction Cache MCF5253 Reference Manual Rev 1 5 10 Freescale Semiconductor...
Page 104: ...Static RAM SRAM MCF5253 Reference Manual Rev 1 6 6 Freescale Semiconductor...
Page 128: ...Synchronous DRAM Controller Module MCF5253 Reference Manual Rev 1 7 24 Freescale Semiconductor...
Page 144: ...Bus Operation MCF5253 Reference Manual Rev 1 8 16 Freescale Semiconductor...
Page 176: ...System Integration Module SIM MCF5253 Reference Manual Rev 1 9 32 Freescale Semiconductor...
Page 198: ...Analog to Digital Converter ADC MCF5253 Reference Manual Rev 1 12 6 Freescale Semiconductor...
Page 246: ...DMA Controller MCF5253 Reference Manual Rev 1 14 18 Freescale Semiconductor...
Page 282: ...UART Modules MCF5253 Reference Manual Rev 1 15 36 Freescale Semiconductor...
Page 344: ...Audio Interface Module AIM MCF5253 Reference Manual Rev 1 17 46 Freescale Semiconductor...
Page 362: ...I2 C Modules MCF5253 Reference Manual Rev 1 18 18 Freescale Semiconductor...
Page 370: ...Boot ROM MCF5253 Reference Manual Rev 1 19 8 Freescale Semiconductor...
