BC41B143A-DS-001PE Datasheet, PDF (65/102 Pages) List of Unclassifed Manufacturers – BlueCpre 4-ROM Single Chip Bluetooth v2.0 System with EDR

Device Terminal Descriptions
10.4.1 UART Bypass
RXD
CTS
RTS
TXD
Host Processor
RESET
UART_TX
UART_RTS
UART_CTS
UART_RX
PIO4
PIO5
PIO6
PIO7
UART
TX
RTS
CTS
RX
Another Device
Test Interface
BlueCore4-ROM
Figure 10.13: UART Bypass Architecture
10.4.2 UART Configuration While RESET is Active
The UART interface for BlueCore4-ROM while the chip is being held in reset is tri-state. This will allow the user to
daisy chain devices onto the physical UART bus. The constraint on this method is that any devices connected to
this bus must tri-state when BlueCore4-ROM reset is de-asserted and the firmware begins to run.
10.4.3 UART Bypass Mode
Alternatively, for devices that do not tri-state the UART bus, the UART bypass mode on BlueCore4-ROM can be
used. The default state of BlueCore4-ROM after reset is de-asserted, this is for the host UART bus to be
connected to the BlueCore4-ROM UART, thereby allowing communication to BlueCore4-ROM via the UART. All
UART bypass mode connections are implemented using CMOS technology and have signalling levels of 0V and
VDD_PADS⁽¹⁾.
In order to apply the UART bypass mode, a BCCMD command will be issued to BlueCore4-ROM upon this, it will
switch the bypass to PIO[7:4] as shown in Figure 10.13. Once the bypass mode has been invoked,
BlueCore4-ROM will enter the deep sleep state indefinitely.
In order to re-establish communication with BlueCore4-ROM, the chip must be reset so that the default
configuration takes affect.
It is important for the host to ensure a clean Bluetooth disconnection of any active links before the bypass mode
is invoked. Therefore it is not possible to have active Bluetooth links while operating the bypass mode.
10.4.4 Current Consumption in UART Bypass Mode
The current consumption for a device in UART Bypass Mode is equal to the values quoted for a device in
standby mode.
Note:
(1)
The range of the signalling level for the standard UART described in section 10.4 and the UART bypass
may differ between CSR BlueCore devices, as the power supply configurations are chip dependent.
For BlueCore3-Multimedia the standard UART is supplied by VDD_USB so has signalling levels of 0V
and VDD_USB. Whereas in the UART bypass mode the signals appear on the PIO[4:7] which are
supplied by VDD_PADS, therefore the signalling levels are 0V and VDD_PADS.
BC41B143A-ds-001Pe
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