Transducer Serial Interface Configuration via Sense Pin Resistance
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Solution Overview
Problem
Existing audio transducer devices, such as microphones and loudspeakers in mobile computing devices, face challenges in identifying and switching between different serial interface formats like PDM and Soundwire, which limits their functionality and requires additional pins or complex re-engineering, especially when multiple devices need to be addressed on a bus.
Innovation Solution
A data interface for transducer devices that uses a controller to determine resistance values and voltage polarity at a sense terminal to selectively operate in either a PDM or Soundwire mode, allowing devices to identify their interface and address without additional pins, by configuring the timing and data transmission based on detected resistance ranges and voltage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transducer device uses additional pins to identify interface format and device address, then the device can support multiple serial interface formats (PDM and Soundwire), but the pin count increases and device size increases
Solution Approach 1:
The patent merges the interface format identification and device address identification functions into a single existing sense pin. By detecting different resistance values at this one pin, the system can distinguish between PDM and Soundwire modes and simultaneously identify the device address, eliminating the need for separate identification pins and reducing overall pin count.
Solution Approach 2:
The sense pin is designed to serve multiple functions: it acts as a sense pin for analog-to-digital conversion, an identification pin for interface format detection, and an address identification pin for device addressing. This multi-functionality allows the transducer device to support multiple interface formats without increasing pin count or device package size.
2Reliability
If a transducer device uses additional pins for interface identification, then it can reliably identify the interface format, but the pin dimensions are reduced and connection reliability deteriorates
Solution Approach 1:
The patent combines interface format identification and device address identification into a single sense pin, maintaining full pin dimensions and connection reliability. The identification is achieved through detecting different resistance values at this pin rather than using separate smaller pins, thus avoiding the pin dimension reduction problem.
3Reliability
If separate microphone devices are manufactured for different bus formats, then each device is optimized for its specific format, but production complexity increases and future upgrades require re-engineering
Solution Approach 1:
The patent implements a universal transducer device design that can operate in multiple serial interface formats (PDM and Soundwire) through software configuration based on resistance value detection. This single device design replaces the need for separate PDM-optimized and Soundwire-optimized devices, simplifying production and enabling future format upgrades without re-engineering the acoustic components.
Solution Approach 2:
The transducer device incorporates dynamic configuration capability where the interface format and device address can be changed by modifying the resistance value detected at the sense pin. This allows the same hardware to adapt to different interface requirements, providing production flexibility and ease of upgrade while maintaining format-specific optimization through software.
4Reliability
If multiple identity pins are used to define device address in Soundwire mode, then device addressing is reliable, but the device complexity increases
Solution Approach 1:
The patent merges device address identification with interface format detection by using the same sense pin for both purposes. Different resistance values indicate both the interface format (PDM or Soundwire) and the device address simultaneously, eliminating the need for multiple separate identity pins and reducing device complexity while maintaining addressing reliability.
Data Source
AI summary
This application relates to methods and apparatus for configuring a serial data interface, especially a data interface (300) for a transducer (324) such as a digital microphone or loudspeaker. The data interface is selectively operable in a first or second serial data mode of operation for input of data to or output data from the transducer device. The first and second serial data modes are different, e.g. correspond to different serial formats. The data interface has a controller (330) configured to determine a resistance value (331, 332) at a sense terminal (314) of the transducer device and to control the data interface in the first serial data mode if the resistance value is within a first resistance range and control the data interface in the second serial data mode if the resistance value is within a second, different, resistance range.