WM9714L_06 WOLFSON [Wolfson Microelectronics plc], WM9714L_06 Datasheet - Page 55

• Manufacturer Part Number: WM9714L_06
• Description: AC 97 Audio CODEC
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

Pre-Production
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In a polling routine, the CPU starts each measurement individually by writing to the POLL bit (register
74h, bit 9). This bit automatically resets itself when the measurement is completed.
Table 47 AUX ADC Control (Initiation of Measurements)
In continuous mode (CTC = 1), the WM9714L autonomously initiates measurements (or sets of
measurements) at the rate set by CR, and supplies the measured data to the CPU on one of the
unused AC’97 time slots. DMA-enabled CPUs can write the data directly into a FIFO without any
intervention by the CPU core. This reduces CPU loading and speeds up the execution of user
programs in handheld systems.
Note that the measurement frequency in continuous mode is also affected by the DEL bits. The
faster rates achieved when DEL = 1111 may be useful when the ADC is used for multiple
measurements.
MEASUREMENT TYPES
The ADCSEL control bits determine which type of measurement is performed (see below).
Table 48 AUX ADC Control (Measurement Types)
The WM9714L performs a single measurement – either in polling mode or continuously, as indicated
by the CTC bit. The type of measurement is specified by the ADCSEL[7:4] bits. Only one of the
ADCSEL[7:4] bits should be set.
74h
76h
74h
REGISTER
REGISTER
ADDRESS
ADDRESS
9
8
9:8
9
8
7
6
5
4
BIT
BIT
POLL
CTC
ADCSEL_AUX4
ADCSEL_AUX3
ADCSEL_AUX2
ADCSEL_AUX1
POLL
CTC
CR
LABEL
LABEL
0
0
00
DEFAULT
0
0
0
0
0
0
DEFAULT
Writing “1” initiates a measurement.
(when CTC is not set)
0: Polling mode
1: Continuous mode (for DMA)
Continuous mode rate (DEL C 1111)
00: 93.75 Hz (every 512 AC-Link frames)
01: 120 Hz (every 400 AC-Link frames)
10: 153.75 Hz (every 312 AC-Link frames)
11: 187.5Hz (every 256 AC-Link frames)
Continuous mode “fast rate” (DEL = 1111)
00: 8 kHz (every six AC-Link frames)
01: 12 kHz (every four AC-Link frames)
10: 24 kHz (every other AC-Link frame)
11: 48 kHz (every AC-Link frame)
Writing “1” initiates a measurement.
(when CTC is not set)
0: Polling mode
1: Continuous mode (for DMA)
Enable COMP1/AUX4 measurement
(pin32). NB: Only one of bits[7:4] should
be set.
Enable COMP1/AUX3 measurement
(pin31) . NB: Only one of bits[7:4] should
be set.
Enable COMP1/AUX2 measurement
(pin30) . NB: Only one of bits[7:4] should
be set.
Enable COMP1/AUX1 measurement
(pin29) . NB: Only one of bits[7:4] should
be set.
DESCRIPTION
DESCRIPTION
PP Rev 3.0 June 2006
WM9714L
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