BT UART Pinmux

Introduction

BT_UART and UART3 works alone

BT_UART works alone

1. Assert BT_USE_EXT_UART (0x4080_A2B8[19] = 0x1) and BT uses external UART.

2. BT UART通过pad与外部通信，Pinmux configure为：

   • BT_UART TXD / RXD / CTS / RTS: PINMUX_FUNCTION_BT (16)

UART3 works alone

1. Assert BT_USE_EXT_UART (0x4080_A2B8[19] = 0x1) and BT uses external UART.

2. UART3通过pad与外部通信，Pinmux configure为：

   • UART3 TXD: PINMUX_FUNCTION_UART3_TXD (103)

   • UART3 RXD: PINMUX_FUNCTION_UART3_RXD (104)

   • UART3 CTS: PINMUX_FUNCTION_UART3_CTS (105)

   • UART3 RTS: PINMUX_FUNCTION_UART3_RTS (106)

BT_UART communicates with UART3

3. De-assert BT_USE_EXT_UART (0x4080_A2B8[19] = 0x0) and BT uses internal UART.

4. BT UART与UART3的输入与输出在电路内部连接，通过Pinmux configure可以monitor中间信号:

   • BT_UART TXD / RTS: PINMUX_FUNCTION_BT (16)

   • UART3 TXD: PINMUX_FUNCTION_UART3_TXD (103)

   • UART3 RTS: PINMUX_FUNCTION_UART3_RTS (106)