AN91267 Datasheet, PDF (45/62 Pages) Ramtron International Corporation – Getting Started with PSoC

Getting Started with PSoC® 4 BLE
Appendix D: PSoC 4 BLE Device
Bluetooth Low Energy Subsystem (BLESS)
The BLE subsystem contains the physical layer (PHY) and link-layer engine with an embedded AES-128 security engine.
The physical layer consists of a digital PHY and RF transceiver compliant with the Bluetooth 4.1 specification. The transceiver
transmits and receives GFSK packets at 1 Mbps over the 2.4-GHz ISM band. The baseband controller is a composite
hardware/firmware implementation that supports both master and slave modes. The key protocol elements such as HCI and
link control are implemented in firmware, while time-critical functions such as encryption, CRC, data whitening, and access
code correlation are implemented in hardware.
The BLESS is Bluetooth 4.1 compliant with support for all the features of the Bluetooth 4.0 specification and some additional
features of the Bluetooth 4.1 specification such as low-duty-cycle advertising, LE ping, and L2CAP connection-oriented
channels. The BLESS block also contains an external crystal oscillator (ECO) and watch crystal oscillator (WCO) that are
required for generating an accurate RF frequency and keeping the time between successive connection intervals on the BLE
link respectively. The ECO and the WCO from the BLESS block can also be used as high-frequency and low-frequency clock
sources for the PSoC 4 BLE system. See the Clocking System section for details.
The BLESS supports five functional power modes: Deep-Sleep, Sleep, Idle, Transmit, and Receive.
Note The power modes discussed in this section are specific to the BLESS block. For PSoC 4 BLE system power modes, see
Low-Leakage Power Modes.
Deep-Sleep Mode
Deep-Sleep mode is the lowest power functional mode supported by the BLESS. In this mode, the radio is off. This mode is
entered for maximum power saving during an advertising or connection interval after the packet transmission and reception is
complete. The ECO can be turned off in this mode for power saving; the WCO, which is the low-frequency clock, is on for
maintaining the BLE link-layer timing reference logic. The CPU controls the entry to and exit from this state.
Sleep Mode
In Sleep mode, the radio is off. The block maintains all the configurations. The ECO and WCO are turned on, but the clock to
the core BLESS logic is turned off. The CPU controls the entry to and exit from this state.
Idle Mode
The Idle mode is the preparation state for the Transmit and Receive states. In this state, the radio is turned off but the link-
layer clock is enabled for the link-layer logic so that the CPU starts the protocol state machines.
Transmit Mode
Transmit mode is the active functional mode; all the blocks within BLESS are powered on. The link-layer clock is enabled to
complete the logic within the link layer and RF-PHY. In this mode, RF-PHY gets 1-Mbps of serial data from the link layer and
transmits the 2.4-GHz GFSK-modulated data to the antenna port. BLE enters Transmit mode from Idle mode.
Receive Mode
This mode enables the BLESS to move into the receive state to perform BLE-specific receiver operations. RF-PHY translates
the 1-Mbps data received from the RF analog block and forwards it to the link-layer controller after demodulation.
A summary of the BLESS power modes and operational sub-blocks is shown in Table 3.
Table 3. BLESS Power Modes
BLESS Power
Mode
Deep-Sleep
Sleep
Idle
Transmit
Receive
RF
ECO WCO Tx
Off On Off
On On Off
On On Off
On On On
On On Off
RF
Rx
Off
Off
Off
Off
On
BLESS
Core
Off
Off
On
On
On
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Document No. 001-91267 Rev. *D
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