User's Manual
Table Of Contents
- Contents
- Table Index
- Figure Index
- 0. Revision history
- 1. Introduction
- 2. Product concept
- 3. Application interface
- 3.1. Pin of module
- 3.2. Operating modes
- 3.3. Power supply
- 3.4. Power on and down scenarios
- 3.5. Charge interface
- 3.6. Power saving
- 3.7. Summary of state transition
- 3.8. RTC backup
- 3.9. Serial interfaces
- 3.10. Audio interfaces
- 3.11. SIM card interface
- 3.12. SD card interface
- 3.13. PCM interface
- 3.14. ADC
- 3.15. Behaviors of the RI
- 3.16. Network status indication
- 3.17. Operating status indication
- 4. Antenna interface
- 5. Electrical, reliability and radio characteristics
- 6. Mechanical dimensions
- 7. Storage and manufacturing
- Appendix A: GPRS coding schemes
- Appendix B: GPRS multi-slot classes
M50 Hardware Design
M50_HD_V2.0 - 62 -
3.13. PCM interface
M50 supports PCM interface. It is used for digital audio transmission between the module and the
customer’s device. This interface is composed of PCM_CLK, PCM_SYNC, PCM_IN and
PCM_OUT signal lines.
Pulse-code modulation (PCM) is a converter that changes the consecutive analog audio signal to
discrete digital signal. The whole procedure of Pulse-code modulation contains sampling,
quantizing and encoding.
Table 21: Pin definition of PCM interface
Name Pin I/O Description
PCM_CLK 19 O PCM clock
PCM_IN 18 I PCM data input
PCM_OUT 20 O PCM data output
PCM_SYNC 21 O PCM frame synchronization
3.13.1. Configuration
M50 supports 16 bits line code PCM format. The sample rate is 8 KHz, the clock source is 256
KHz, and the module can only act as master mode. The PCM interfaces support long and short
synchronization simultaneously. It only supports MSB first. For more detailed information, please
see the table below.
Table 22: Configuration
PCM
Line interface format Linear
Data length Linear: 16 bits
Sampling rate 8KHz
PCM clock/synchronization
source
PCM master mode: clock and synchronization is generated
by module
PCM synchronization rate 8KHz
PCM clock rate PCM master mode:256 KHz
PCM synchronization format Long/short synchronization
PCM data ordering MSB first
Zero padding Yes
Sign extension Yes
Quecctel
Confidential