lm49370rl National Semiconductor Corporation, lm49370rl Datasheet - Page 17

• Manufacturer Part Number: lm49370rl
• Description: Audio Sub-system With An Ultra Low Emi, Spread Spectrum, Class D Loudspeaker Amplifier, A Dual-mode Stereo Headphone Amplifier, And A Dedicated Pcm Interface For Bluetooth Transceivers
• Manufacturer: National Semiconductor Corporation

Method 2. SPI/Microwire Control/3–wire Control
The LM49370 can be controlled via a three wire interface consisting of a clock, data and an active low chip_select. To use this
control method connect SPI_MODE to BB_V
and use TEST_MODE/CS as the chip_select as follows:
DD
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FIGURE 3. SPI Write Transaction
If the application requires read access to the register set; for example to determine the cause of an interrupt request, the GPIO2
pin can be configured as an SPI format serial data output by setting the GPIO_SEL in the GPIO configuration register (0x1Ah) to
SPI_SDO. To perform a read rather than a write to a particular address the MSB of the register address field is set to a 1, this
effectively mirrors the contents of the register field to read-only locations above 0x80h:
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FIGURE 4. SPI Read Transaction
Three Wire Mode Write Bus Timing
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FIGURE 5. SPI Timing
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