This section describes the necessary
steps to configure the PCMD3140 for this specific application. The following steps
provide a sequence of items that must be executed in the time between powering the
device up and reading data from the device or transitioning from one mode to another
mode of operation.
- Apply power to the device:
- Power-up the IOVDD and AVDD power supplies
- Wait for at least 1 ms to
allow the device to initialize the internal registers
initialization
- The device now goes into sleep shutdown mode (low-power
mode < 10 µA)
- Transition from sleep mode to active mode whenever required for
the recording operation:
- Wake up the device by writing to P0_R2 to disable sleep
mode
- Wait for at least 1 ms to allow the device to complete
the internal wake-up sequence
- Override the default configuration registers or
programmable coefficients value as required (this step is optional)
- Configure channel 1 to channel 2 (CHx_INSRC) for the
digital microphone as the input source for recording
- Configure GPO1 (GPO1_CFG) and GPIO1 (GPIO1_CFG) as the
PDMCLK output
- Configure GPIx (GPI1x_CFG) as PDMDINx
- Enable all desired input channels by writing to
P0_R115
- Enable all desired audio serial interface output
channels by writing to P0_R116
- Power-up the PDM converter and PLL by writing to
P0_R117
- Apply FSYNC and BCLK with the desired output sample
rates and the BCLK to FSYNC ratio
This specific step
can be done at any point in the sequence after step a.
See the Section 7.3.2 section for supported sample rates and
the BCLK to FSYNC ratio.
- The device recording data is now sent to the host
processor using the TDM audio serial data bus
- Transition from active mode to sleep mode (again) as required
in the system for low-power operation:
- Enter sleep mode by writing to P0_R2 to enable sleep
mode
- Wait at least 6 ms (when FSYNC = 48 kHz) for the volume
to ramp down and for all blocks to power down
- Read P0_R119 to check the device shutdown and sleep
mode status
- If the device P0_R119_D7 status bit is 1'b1 then stop
FSYNC and BCLK in the system
- The device now goes into sleep mode (low-power mode
< 10 µA) and retains all register values
- Transition from sleep mode to active mode (again) as required
for the recording operation:
- Wake up the device by writing to P0_R2 to disable sleep
mode
- Wait at least 1 ms to allow the device to complete the
internal wake-up sequence
- Apply FSYNC and BCLK with the desired output sample
rates and the BCLK to FSYNC ratio
- The device recording data are now sent to the host
processor using the TDM audio serial data bus
- Repeat step 3 and step 4 as required for mode transitions and
step 2 to step 4 for configuration changes.