BES2300-Z Product Specification
2.12 CLOCK GENERATIONExternal reference clock (OSC) comes from the pad XTAL_IN, such as a crystal of
26MHz. On chip BB PLL and audio PLL are available for MCU system. PLLs should be power off to save power if not necessary.
PLL_AUD(Internal)1MUX0x40080018[6]0X4(oscx4)X2(oscx2)0MUX0x40080018[15]11SWITCH0x40000060[8]0Clock GatingMCU SysPLL_BB(Internal)1SWITCH0x40000060[7]0OSC(XTAL_IN)26MHz1SWITCH0x40000060[6]01SWITCH0x40000060[3]0Clock GatingFlash1SWITCH0x40000060[2]0LPO_32K(Internal)1SWITCH0x40000060[1]01SWITCH0x4000005C[4]01SWITCH0x400000A8[18,25]01SWITCH0x40000070[5,13,21]01SWITCH0x40000074[9]01SWITCH0x40000074[8]0Clock GatingI2CClock GatingUARTx3Clock GatingSPIx2Clock GatingSDEMMCFigure 2-20 BES2300-Z Main Clocks Management Schematic
BES2300-Z Product Specification
3 Bluetooth Modem Description
3.1 BLUETOOTH RF TRANSCEIVER ARCHITECTURE
3.1.1 RF Transceiver
BES2300-Z integrates a Bluetooth transceiver with minimum external components. The architecture is illustrated as Figure 5-1. It contains an on-chip transformer and T/R switch, which is shared by the receiver Low Noise Amplifier (LNA) and the transmitter Power Amplifier (PA). RF synthesizer also included in the transceiver without any external components. Matching network is recommended for better sensitivity and power efficiency.
LNAMIXERMNVCOFILTERFILTERADCRFPLLMIXERPADAC
Figure 3-1 Bluetooth transceiver architecture
3.1.2 RF Receiver
The receiver features a low-if architecture and integrates on-chip LNA and channel filters. The LNA operates in differential mode to have good noise figure performance. Good out-of-band blocking performance enables the receiver to operate in close proximity with cellular phone transmitters without being blocked. A high resolution ADC in the receiver digitizes the IF signal and passes the information to the digital modem. The receiver ADC also samples the input voltage on a slot-by-slot basis. The LNA, mixer and filter gain are changed according to the measured RSSI value, fulfilling the fast AGC procedure, and improving the dynamic range in different interference conditions.
3.1.3 RF Transmitter
The transmitter features a direct-conversion I/Q modulator to enable both basic data rate and enhanced data rate Bluetooth signal transmission without any off-chip high Q band-pass filter. This transmitter simplified design and minimum frequency drift. The on-chip PA output power can be configured to different values by software. The
BES2300-Z Product Specification
Maximum output power of the PA enables it to operate as Class1, Class 2 and Class 3 Bluetooth radio without requiring an external PA.
3.1.4 RF Synthesizer
The Bluetooth RF synthesizer including VCO and phase-lock loop is fully integrated into the chip without any external components. The synthesizer is guaranteed to lock in several tens of microseconds within sufficient accuracy to meet the Bluetooth V4.2 specification.
3.2 BLUETOOTH PHY ARCHITECTURE
3.2.1 Digital PHY Architecture
The Digital PHY includes two parts: receiver (Rx) core and transmitter (Tx) core as illustrated in Figure 3-2.
RX CORERF TransceiverTX COREBluetooth Mac
Figure 3-2 Digital PHY Architecture
3.2.2 Digital PHY Receiver Parts
The Digital PHY Receiver of Bluetooth Modem includes the following modules: ? ?
RX_FRONTEND is used for down-sampling the received data from transceiver; RX_GFSK is used for the demodulation of GFSK signal;
BES2300-Z Product Specification
? ?
RX_DPSK is used for the demodulation of DPSK signal;
DATA_MUX is used for data selection between GFSK demodulator and DPSK demodulator.
The input data from RF transceiver is 2-bits. After the demodulation, the 3-bits data is sent to the Bluetooth MAC. The signal flow of the digital PHY receiver is illustrated as Figure 5-3:
RX_GFSKRX_FRONTENDRX_DPSKDATA_MUXADC DataTo MAC Data
Figure 3-3 the signal flow of the digital PHY receiver
3.2.3 Digital PHY Transmitter Parts
The digital PHY transmitter of the Bluetooth Modem includes the following modules, it generates the Bluetooth packets from the MAC data. ? ? ? ?
TX_DATA_RECOVERY is used to capture the data from baseband providing a 1MHz reference pulse and its related phase counter;
TX_GFSK is used to perform GFSK modulation; TX_DPSK is used to perform DPSK modulation;
TX_SWITCH is used to compensate the latency and make selection between GFSK and DPSK data within Bluetooth packets.
TX_GFSKTX_DATA_RECOVERYTX_DPSKTX_SWITCHData from MACDATA to ADC
Figure 3-4 Digital PHY Transmitter Parts
BES2300-Z Product Specification
3.3 BLUETOOTH MAC ARCHITECTURE
The Bluetooth MAC compliant with Bluetooth 5.0 dual mode. The top-level diagram is illustrated as Figure 3-5. There are three main parts in Bluetooth MAC: audio data path, Bluetooth data path, finite state machine (FSM) control and two main parts in BLE core: BLE data path, FSM control. Clock generation, timing generation, radio controller and bus interface are designed for configuration purpose.
The advanced microcontroller bus architecture (AMBA) is used to communicate with Bluetooth MAC and ARM processor. The AMBA also provides processor access to audio path, data path and register files for configuration purpose.
A specific interface is provided for voice data to the real time Bluetooth Core layer, in order to be able to process a continuous voice stream without the need of a processor real time intervention. A voice codec, or microphone / speaker components can be plugged on the audio path PCM interface to enable voice capabilities.
Before MAC sends data to PHY or after MAC received data from PHY, the data must be processed in data path. CRC check, FEC, whiten and encrypt are all processed in this module.
The FSM control is configured for scheduling the transmitter and receiver timing, control signal generation, data load and store control.
The 26 MHz clock is used for the normal use of MAC, and the 32 KHz is used for sleep mode, they are both generated by the clock generation blocks. Timing generation is mainly responsible for state switching between normal mode and sleep mode.
A radio blocks is plugged on the radio controller or data path interfaces through the RF interface, which is responsible for converting baseband signals to radio frequency.
CODECCMUBluetooth PHYProcessor SystemRF TransceiverAudio DatapathClock GenerationBluetooth DatapathBLE DatapathFrequency SelectionInterrupt controlFrequency SelectionInterrupt controlBus InterfaceBLE RegisterBluetooth RegisterRF ControllerTiming Generation Figure 3-5 Bluetooth top-level diagram
BES2300
