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Discussion Groups | AT91SAM ARM | Questions on using SSC interface with PCM bus
For users of the Atmel AT91SAM7 and AT91SAM9 ARM CPU chips. Atmel has taken a new direction by combining on chip flash and ram with the ARM CPU on a single die. This provides low cost devices for small systems using the ARM CPU. This group is to exchange information to help users get started and learn how to use the devices.
Questions on using SSC interface with PCM bus - faiy...@gmail.com - Feb 24 1:50:12 2009
Dear All,
We are using AT91SAM7S64 for one of our telecom related project. We are using several SLICs and DAAs in our design. Now there is a PCM bus in each SLIC and DAA to send and recieve voice samples. We have connected this PCM bus to the SSC interface of the MCU. And we are planning to have 32 input and output channels on this PCM bus. My first question is can we use single SSC interface to do both operations - transmission and reception of voice samples from and to the PCM bus???? And If yes can we have 32 channels (ie slots per frame) on both input and output?
Our sampling frequency is 8 KHz and there will be 8 bits per sample. Now to keep in mind the future requirements we have given 2.048 MHz clock to the transmitter and receiver of the SSC interface by external hardware. This corresponds to 32 timeslots per each frame. But right now we are using only 2 time slots on the PCM bus. I mean the other timeslots are unused. So my second question is what should I write in the DATNB field of the TFMR(Transmit Frame Mode Register) and RFMR registers of SSC Interface? Should I write (32-1)? or should I write (2-1)?
Now as the sampling freq is 8 KHz the frame will be of 125 us. But we want to read the received the voice samples every millisecond. And in one millisecond there will be 8 voice samples of each channel(timeslot). So my question is can the SSC interface store 8 voice samples of each channel in a single transfer? If yes then how will it store the samples in the buffer? will it store like - one sample of each channel then second sample of each channel and so on? or will it store like - 8 continuous samples of one channel then 8 samples of second channel and so on?
Or do we have to read 1 voice samples of all channels every 125 us?
Please can anyone who has worked on SSC answer my questions?
Thanks & regards
Faiyaz Pisuwala
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!
(You need to be a member of AT91SAM -- send a blank email to AT91SAM-subscribe@yahoogroups.com )
We are using AT91SAM7S64 for one of our telecom related project. We are using several SLICs and DAAs in our design. Now there is a PCM bus in each SLIC and DAA to send and recieve voice samples. We have connected this PCM bus to the SSC interface of the MCU. And we are planning to have 32 input and output channels on this PCM bus. My first question is can we use single SSC interface to do both operations - transmission and reception of voice samples from and to the PCM bus???? And If yes can we have 32 channels (ie slots per frame) on both input and output?
Our sampling frequency is 8 KHz and there will be 8 bits per sample. Now to keep in mind the future requirements we have given 2.048 MHz clock to the transmitter and receiver of the SSC interface by external hardware. This corresponds to 32 timeslots per each frame. But right now we are using only 2 time slots on the PCM bus. I mean the other timeslots are unused. So my second question is what should I write in the DATNB field of the TFMR(Transmit Frame Mode Register) and RFMR registers of SSC Interface? Should I write (32-1)? or should I write (2-1)?
Now as the sampling freq is 8 KHz the frame will be of 125 us. But we want to read the received the voice samples every millisecond. And in one millisecond there will be 8 voice samples of each channel(timeslot). So my question is can the SSC interface store 8 voice samples of each channel in a single transfer? If yes then how will it store the samples in the buffer? will it store like - one sample of each channel then second sample of each channel and so on? or will it store like - 8 continuous samples of one channel then 8 samples of second channel and so on?
Or do we have to read 1 voice samples of all channels every 125 us?
Please can anyone who has worked on SSC answer my questions?
Thanks & regards
Faiyaz Pisuwala
------------------------------------
______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!
(You need to be a member of AT91SAM -- send a blank email to AT91SAM-subscribe@yahoogroups.com )