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Application that uses the PDM driver and the UART driver.
Board_LED1 - Indicates that the board was initialized within main(), and that sampling is not in progress.
Board_LED2 - Toggles every 16 sample blocks
Board_BUTTON0 - Button to start stream
Board_BUTTON1 - Button to stop stream
Display - Used to write information about the stream. It can either be the LCD devpack or simply UART. Information about the stream includes volume indication.
Please refer to the development board’s specific “Settings and Resources” section in the Getting Started Guide. For convenience, a short summary is also shown below.
| Development board | Notes |
|---|---|
| CC2650STK | |
| CC1350STK |
Fields left blank have no specific settings for this example.
Run the example. Board_LED1 turns ON to indicate that TI-RTOS driver initialization is complete. It is turned off as the PDM driver is started.
A stream is started when the user presses Board_BUTTON0. Board_LED1 remains off until the stream ends. The stream ends when user presses Board_BUTTON1, or if there is an error in the stream.
While the stream is running Board_LED1 toggles on and off with a period based on the sample rate. The period is 32 frames, duty cycle 50%. One frame is 192 samples, @16kHz, which gives a period of 364ms.
When the application is running, open a serial session (e.g. HyperTerminal, puTTY, etc.) to the appropriate COM port.
The COM port can be determined via the Device Manager in Windows or via
ls /dev/tty*in Linux.
The connection should have the following settings
Baud-rate: 115200
Data bits: 8
Stop bits: 1
Parity: None
Flow Control: NoneIf the serial session is started before the target completes initialization, the following is displayed: Starting PDM stream:
This example shows how to use the PDM driver to start and stop a stream from a digital microphone.
It uses the UART driver to write information about the stream to a host application, and uses the most basic button driver to let user control start/stop of stream.