RM0082
RS_Telecom IP
Doc ID 018672 Rev 1
773/844
1.
For Narrowband (8 kHz), Companded (8 bit) samples
- The pointer will progress by 1
byte at each frame.
2.
For Narrowband, Linear (16 bits) samples
- The pointer will progress by 2 bytes at each
frame. The two bytes will be in consecutive time slots.
3.
For Wideband companded samples
- The pointer will also progress by 2 bytes at each
frame. Anyway, the first sample will be in the first half of the frame and the second
sample in the second half.
4.
For Wideband linear samples
- The pointer will progress by 4 bytes at each frame. Two
bytes are located in the first half of the frame, two others in the second half.
Figure 90.
Various type of data carried by the TDM bus
To manage any data type using a single counter, a frame counter is implemented. From the
above diagram, the location where the sample will has to be stored inside the current buffer
area is given by:
●
Frame counter for the first configuration
●
Frame counter and one LSB (offset bits inside the
action memory
) for the second and
third configuration
●
Frame counter and two LSB (offset bits the
action memory
) for the fourth configuration
●
The bank information
●
The channel number
Figure 91.
Address generation and bank switching
Shown below is an example of storing 3 successive frames of the same channel (channel
0), considering the two narrowband cases with odd memory bank used for buffering
samples.
Half Frame
Frame
Narrowband Companded
Narrowband linear
Wideband Companded
Wideband linear
0000
3FFF
4000
7FFF
Odd Buffer
Even Buffer
byte0
byte1
byte2
byte3
Acion
memory
1
st
offset bit
2
nd
offset bit
10 bits frame
counter
Channel
Bank bit
