Specifications

LEON-G100/G200 - System Integration Manual
GSM.G1-HW-09002-C Preliminary System description
Page 39 of 75
I2S_TX word can be written while I2S_WA is high, low or both;
MSB can be 1 bit delayed or non-delayed on I2S_WA edge;
I2S_TX data can change on rising or falling edge of I2S_CLK signal (Rising edge in this example);
I2S_RX data read on the opposite front of I2S_CLK signal.
1.9.3 Voiceband processing system
Digital voiceband processing on the LEON-G100/G200 is implemented in the DSP core inside the baseband
chipset. The analog audio front-end of the chipset is connected to the digital system through 16 bit ADC
converters in the uplink path, and through 16 bit DAC converters in the downlink path. The digitized TX and RX
voiceband signals are both processed by digital gain stages and decimation filter in TX, interpolation filters in RX
path. The processed digital signals of TX and RX are connected to the TEAKLite DSP for various tasks (i.e. speech
codec, digital mixing and sidetone, audio filtering) implemented in the firmware modules.
External digital audio devices can be interfaced to the DSP voiceband processing system via the I2S interface.
The voiceband processing system can be split up into three different parts:
Sample-based Voiceband Processing (at 8 kHz / 125 µs)
Frame-based Voiceband Processing (20 ms)
Circular Mixing Buffer, to mix different sound signals (Sound Ringer, MIDI synthesizer) with the downlink
signal at 48 kHz
LEON-G100/G200
Mic-1
Mic-2
Receiver
Loud
Speaker
I2Sy
TX
(Normal I2S mode)
I2Sy
RX
(Normal I2S mode)
Sample-based
Voiceband Processing
DTMF Tones (UL & DL)
Filtering (IIR & FIR)
Sidetone
Frame-based
Voiceband Processing
Voice Memo
Hands Free
Circular
Mixing Buffer
Sample Rate Conversion
MIDI Synthesizer
MODEM
TX
RX
Digital
Audio
Input
I2Sx
TX
(PCM mode)
I2Sx
RX
(PCM mode)
Analog Front End
TX
Analog Front End
RX
Digital
Audio
Output
LEON-G100/G200
Mic-1
Mic-2
Receiver
Loud
Speaker
I2Sy
TX
(Normal I2S mode)
I2Sy
RX
(Normal I2S mode)
Sample-based
Voiceband Processing
DTMF Tones (UL & DL)
Filtering (IIR & FIR)
Sidetone
Frame-based
Voiceband Processing
Voice Memo
Hands Free
Circular
Mixing Buffer
Sample Rate Conversion
MIDI Synthesizer
MODEM
TX
RX
Digital
Audio
Input
I2Sx
TX
(PCM mode)
I2Sx
RX
(PCM mode)
Analog Front End
TX
Analog Front End
RX
Digital
Audio
Output
Figure 24: LEON-G100/G200 voiceband processing system block diagram