STLC2500A View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'STLC2500A' PDF : 37 Pages View PDF
HCI UART transport layer
8
HCI UART transport layer
STLC2500A
The UART transport Layer has been specified by the Bluetooth SIG and allows HCI level
communication between a Bluetooth Controller (STLC2500A) and a Host (e.g. a GSM), via
a serial line.
The objective of this HCI UART Transport Layer is to make possible to use Bluetooth HCI
over a serial interface between two UARTs on the same PCB. The HCI UART Transport
Layer assumes that the UART communication is free from line errors.
UART Settings
The HCI UART Transport Layer uses the following settings for RS232:
– Baud rate:
configurable (default baud rate 115.2 [kbps])
– Number of data bits:
8
– Parity bit:
no parity
– Stop bit:
1 stop bit
– Flow control:
RTS/CTS
– Flow-off response time: 3ms
The flow-off response time defines the maximum time from setting RTS low until the byte
flow actually stops.
RTS/CTS flow control is used to prevent temporary UART buffer overrun between the
Bluetooth Controller and the Host.
It should not be used for flow control of HCI, as HCI has its own flow control mechanism for
commands, events and data.
The RS232 signals should be connected in a null-modem fashion, i.e. the Bluetooth
Controller TXD output should be connected to the Host RXD input and the Bluetooth
Controller RTS output should be connected to the Host CTS input and vice versa.
If the Bluetooth Controller RTS output (connected to the Host CTS input) is high, then the
Host is allowed to send.
If the Bluetooth Controller RTS output (connected to the Host CTS input) is low, then the
Host is not allowed to send.
If the Bluetooth Controller CTS input (connected to the Host RTS output) is high, then the
Bluetooth Controller is allowed to send.
If the Bluetooth Controller CTS input (connected to the Host RTS output) is low, then the
Bluetooth Controller is not allowed to send.
Figure 14. UART transport layer
BLUETOOTH
HOST
BLUETOOTH HCI
BLUETOOTH
HOST
CONTROLLER
HCI UART TRANSPORT LAYER
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