Configuring the Firmware

The default application performs as described in the Overview. There are numerous compile time options that can be added to change the example design without requiring code changes. To change the options explained in the table below, add the desired configuration variables to the APP_COMPILE_DEFINITIONS cmake variable in the .cmake file located in the examples/ffd/ folder.

If options are changed, the application firmware must be rebuilt.

Table 2 FFD Compile Options

Compile Option	Description	Default Value
appconfINTENT_ENABLED	Enables/disables the intent engine, primarily for debug.	1
appconfINTENT_RESET_DELAY_MS	Sets the period after the wake up phrase has been heard for a valid command phrase	5000
appconfINTENT_RAW_OUTPUT	Set to 1 to output all keywords found, skipping the internal wake up and command state machine	0
appconfAUDIO_PLAYBACK_ENABLED	Enables/disables the audio playback command response	1
appconfINTENT_UART_OUTPUT_ENABLED	Enables/disables the UART intent message	1
appconfINTENT_UART_DEBUG_INFO_ENABLED	Enables/disables the UART intent debug information	0
appconfI2C_MASTER_DAC_ENABLED	Enables/disables configuring the DAC over I2C master	1
appconfINTENT_I2C_MASTER_OUTPUT_ENABLED	Enables/disables sending the intent message over I2C master	1
appconfINTENT_I2C_MASTER_DEVICE_ADDR	Sets the address of the I2C device receiving the intent via the I2C master interface	0x01
appconfINTENT_I2C_SLAVE_POLLED_ENABLED	Enables/disables allowing another device to poll the intent message via I2C slave	0
appconfI2C_SLAVE_DEVICE_ADDR	Sets the address of the I2C device receiving the intent via the I2C slave interface	0x42
appconfINTENT_I2C_REG_ADDRESS	Sets the address of the I2C register to store the intent message, this value can be read via the I2C slave interface	0x01
appconfUART_BAUD_RATE	Sets the baud rate for the UART tx intent interface	9600
appconfUSE_I2S_INPUT	Replace I2S audio source instead of the microphone array audio source.	0
appconfI2S_MODE	Select I2S mode, supported values are appconfI2S_MODE_MASTER and appconfI2S_MODE_SLAVE	master
appconfI2S_AUDIO_SAMPLE_RATE	Select the sample rate of the I2S interface, supported values are 16000 and 48000	16000
appconfRECOVER_MCLK_I2S_APP_PLL	Enables/disables the recovery of the MCLK from the Software PLL application; this removes the need to use an external MCLK.	0
appconfINTENT_TRANSPORT_DELAY_MS	Sets the delay between host wake up requested and I2C and UART keyword code transmission	50
appconfINTENT_QUEUE_LEN	Sets the maximum number of detected intents to hold while waiting for the host to wake up	10
appconfINTENT_WAKEUP_EDGE_TYPE	Sets the host wake up pin GPIO edge type. 0 for rising edge, 1 for falling edge	0
appconfAUDIO_PIPELINE_SKIP_IC_AND_VNR	Enables/disables the IC and VNR	0
appconfAUDIO_PIPELINE_SKIP_NS	Enables/disables the NS	0
appconfAUDIO_PIPELINE_SKIP_AGC	Enables/disables the AGC	0

Note

The example_ffd_i2s_input_cyberon has different default values from the ones in the table above. The list of updated values can be found in the APP_COMPILE_DEFINITIONS list in examples\ffd\ffd_i2s_input_cyberon.cmake.

Configuring the I²C interfaces

The I²C interfaces are used to configure the DAC and to communicate with the host. The I²C interface can be configured as a master or a slave. The DAC must be configured at bootup via the I²C master interface. The I²C master is used when the FFD example asynchronously sends intent messages to the host. The I²C slave is used when the host wants to read intent messages from the FFD example through polling.

Note

The I²C interface cannot operate as both master and slave simultaneously. The FFD example design uses the I²C master interface to configure the DAC at device initialisation. However, if the host reads intent messages from the FFD example using the I²C slave interface, the I²C master interface will be disabled after the DAC configuration is complete.

To send the intent ID via the I²C master interface when a command is detected, set the following variables:

• appconfINTENT_I2C_MASTER_OUTPUT_ENABLED to 1.

• appconfINTENT_I2C_MASTER_DEVICE_ADDR to the desired address used by the I²C slave device.

• appconfINTENT_I2C_SLAVE_POLLED_ENABLED to 0, this will disable the I²C slave interface.

To configure the FFD example so that the host can poll for the intent via the I²C slave interface, set the following variables:

• appconfINTENT_I2C_SLAVE_POLLED_ENABLED to 1.

• appconfI2C_SLAVE_DEVICE_ADDR to the desired address used by the I²C master device.

• appconfINTENT_I2C_REG_ADDRESS to the desired register read by the I²C master device.

• appconfINTENT_I2C_MASTER_OUTPUT_ENABLED to 0, this will disable the I²C master interface after initialization.

The handling of the I²C slave registers is done in the examples\ffd\src\i2c_reg_handling.c file. The variable appconfINTENT_I2C_REG_ADDRESS is used in the callback function read_device_reg().

Configuring the I²S interface

The I²S interface is used to play the audio command response to the DAC, and/or to receive the audio samples from the host. The I²S interface can be configured as either a master or a slave. To configure the I²S interface, set the following variables:

• appconfI2S_ENABLED to 1.

• appconfI2S_MODE to the desired mode, either appconfI2S_MODE_MASTER or appconfI2S_MODE_SLAVE.

• appconfI2S_AUDIO_SAMPLE_RATE to the desired sample rate, either 16000 or 48000.

• appconfRECOVER_MCLK_I2S_APP_PLL to 1 if an external MCLK is not available, otherwise set it to 0.

• appconfAUDIO_PLAYBACK_ENABLED to 1, if the intent audio is to be played back.

• appconfUSE_I2S_INPUT to 1, if the I²S audio source is to be used instead of the microphone array audio source.