STLC2415

18/22

Figure 8. PCM Interface Timing

8

HCI UART TRANSPORT LAYER

communication between a host controller (STLC2415) and a host (e.g. PC), via a RS232 interface.

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:

– 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 to 0 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 9. UART Transport Layer

D02TL557

PCM_CLK

PCM_SYNC

PCM_A/B in

PCM_B/A out

MSB

MSB-1

MSB-2

MSB-3

MSB-4

MSB

MSB-1

MSB-2

MSB-3

MSB-4

BLUETHOOTH

HOST

BLUETHOOTH

HOST

CONTROLLER

HCI UART TRANSPORT LAYER

BLUETHOOTH HCI

D02TL556