STA2416 Datasheet, PDF (33/38 Pages) STMicroelectronics – Bluetooth™ Baseband with integrated flash

STA2416
8
HCI UART transport layer
HCI UART transport layer
The UART Transport Layer has been specified by the Bluetooth™ SIG, and allows HCI level
communication between a host controller (STA2416) and a host (for example, PC), via a
serial line.
The objective of this HCI UART Transport Layer is to make it possible to use the 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.
8.1
UART settings
The HCI UART Transport Layer uses the following settings for RS232:
Baud rate:
Configurable (Default baud rate: 57.600 kbps)
Number of data bits: 8
Parity bit:
no parity
Stop bit:
1 stop bit
Flow control:
RTS/CTS
Flow-off response time: 3 ms
Flow control with RTS/CTS is used to prevent temporary UART buffer overrun. It should not
be used for flow control of HCI, since HCI has its own flow control mechanisms for HCI
commands, HCI events and HCI data.
If CTS is 1, then the Host/Host Controller is allowed to send.
If CTS is 0, then the Host/Host Controller is not allowed to send.
The flow-off response time defines the maximum time from setting RTS low until the byte
flow actually stops. The signals should be connected in a null-modem fashion; i.e. the local
TXD should be connected to the remote RXD and the local RTS should be connected to the
remote CTS and vice versa.
Figure 15. UART transport layer
BLUETHOOTH
HOST
BLUETHOOTH HCI
BLUETHOOTH
HOST
CONTROLLER
HCI UART TRANSPORT LAYER
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