3.1 Module Overview

The RNBD451 Bluetooth Low Energy module integrates the Bluetooth 5.2 baseband controller, Bluetooth stack, digital and analog I/O and RF power amplifier into one solution.

Figure 3-1. RNBD451 Module Block Diagram

Table 3-1. Pin Description
Pin Number	Name	RNBD451 Definition	Type
1	GND	Ground	—
2	GND	Ground	—
3	NMCLR	Reset	I
4	PB0	PTA control (WLAN ACTIVE)	I
5	PB3	Bluetooth® Low Energy status indication pin 1/2	O
6	PB5	Bluetooth status LED	O
7	VDD_A	VDDANA power supply	—
8	GND	Ground	—
9	PA11	Reserved. No Connect	—
10	PA12	Reserved. No Connect	—
11	GND	Ground	—
12	PB6	UART receive data	I
13	PB7	Bluetooth Low Energy status indication pin 2/2	O
14	PB8	I/O level control by RN command	I/O
15	PB9	Reserved. No Connect	—
16	PA4	UART Request to Send (RTS)	O
17	PB10	I/O level control by RN command	I/O
18	PB11	I/O level control by RN command	I/O
19	GND	Ground	—
20	PA0	I/O level control by RN command	I/O
21	PA1	I/O level control by RN command	I/O
22	PB12	I/O level control by RN command	I/O
23	PB13	I/O level control by RN command	I/O
24	PA5	UART transmit data	O
25	PA6	UART Clear to Send (CTS)	I
26	GND	Ground	—
27	VDD	VDD and VDDIO power supply	—
28	VDD	VDD and VDDIO power supply	—
29	PA8	Debug UART receive data. Recommend to add a test point on this pin.	I
30	PA9	Reserved	—
31	PA7	Debug UART transmit data. Recommend to add a test point on this pin.	O
32	PA10	I/O level control by RN command	I/O
33	PA13	PTA control (BT_PRIORITY)	O
34	PA14	PTA control (BT_ACTIVE)	O
35	PA2	UART transmit indication pin	O
36	PA3	Event indication pin (RSSI indication pin)	O
37	PB2	UART mode switch	I
38	PB1	ADC	I
39	PB4	UART receive indication pin/RNBD451 wake-up pin Low-power mode	I
Note: Upon reset, if the PB5 pin is held low, the RNBD451 module sends out REBOOT, MAC ID and firmware version. Upon the RNBD451 module reset, the PB5 pin acts as the input for approximately 300 ms. Post this time, the PB5 pin changes to output and resumes normal functionality, which is Bluetooth status LED. It is recommend to have a 10K pull-up resistor on the UART TXD pin (PA5). For reference, see Application Reference Schematics. For the serial DFU update, the UART pins PB6 (UART receive data) and PA5 (UART transmit data) is used.