参数资料
型号: TAS3001CPWR
厂商: TEXAS INSTRUMENTS INC
元件分类: 音频控制
英文描述: 2 CHANNEL(S), TONE CONTROL CIRCUIT, PDSO28
封装: GREEN, PLASTIC, TSSOP-28
文件页数: 15/55页
文件大小: 432K
代理商: TAS3001CPWR
33
However, this wait cycle does not occur during the volume or tone change command, instead it occurs during the next
command after the acknowledgement of the first data byte.
Table 34 gives typical values of the wait states of the TAS3001 commands.
Table 34. I2C Wait States
SYSTEM SAMPLING FREQUENCY
COMMENT
32 kHz
44.1 kHz
48 kHz
96 kHz
COMMENT
Volume
62 ms
49 ms
41 ms
21 ms
Not dependent on size of change
Bass
231 ms
167 ms
153 ms
77 ms
18 dB to 18 dB (proportional to step
change)
Treble
231 ms
167 ms
153 ms
77 ms
18 dB to 18 dB (proportional to step
change)
Mixer
None
Equalization
None
The I2C operation sequence that the TAS3001 uses to assert an I2C wait cycle is:
1.
The TAS3001 detects a valid start condition and correct device ID. At this point the TAS3001 issues an ACK.
2.
The TAS3001 decodes the eight-bit subaddress and issues another ACK.
3.
The TAS3001 decodes the first data byte and issues a third ACK.
4.
At this point, the TAS3001 device can hold the SCL clock line low until the internal controller is ready to
accept more data. This is an I2C slave wait state.
There are two ways a master can handle the I2C slave wait.
The preferred way to handle wait states is to use an I2C master that recognizes wait states. During the
wait-state period, the master stops sending data over I2C. In this case, when the master releases the clock
to go high after a slave ACK (to latch in the next bit of data), the master monitors the SCL line and ensures
that the slave has released SCL. Once SCL has been released the master can start the next transmission.
Alternatively, if this function is not available on the system controller, fixed delays can be implemented in
the system software to ensure that the TAS3001 is ready to receive additional data. Sending I2C data while
the TAS3002 device is busy causes errors and the device locks up and have to be reset.
Issuing a stop command in the middle of an I2C transaction puts the TAS3001 I2C slave block into an unknown state,
possibly locking up the controller or causing it to send incorrect data to the signal processing block.
3.2.3
Resetting the TAS3001 I2C Interface
To put the TAS3001 back into a known state, an I2C transaction with a subaddress of 00h and followed by 16 bytes
of zeros clears out the I2C slave block buffer. Resetting the device also puts it into a known state.
During normal operation, the TAS3001 should never issue a NACK. If the TAS3001 issues a NACK, this is an
indication of an I2C protocol discrepancy.
3.2.4
Power-Up Conditions
Upon system power up, the I2C bus SCL can initialize in a mode in which the line is held low. This prevents any I2C
operations from being performed. To prevent this from occurring, always hold RESET low for a minimum of 10 MCLK
clock cycles after applying power.
Upon reset, the TAS3001 goes through an initialization sequence with a duration of 5 ms.
Before a reset, the SDA and SCL lines may be held low by the device.
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