Bluetooth 4.2 BLE Serial Module I2C UART SPI

The JDY-16 is a compact (only 20 x 15mm) Bluetooth Low Energy wireless module for low-power embedded communication. It supports both UART and I2C communication modes and offers far more than simple transparent serial passthrough. Depending on firmware configuration, the module can be used for wireless serial communication, app-controlled I/O, PWM control, RTC-related functions, BLE advertising, and master/slave communication.

This module is especially interesting for designers who need a small BLE module that can work either as a classic serial wireless bridge or as a more tightly integrated peripheral controlled by registers over I2C.

Please find the pinout and basic wiring information for serial mode and I2C mode in the image gallery.

Key advantages

• Bluetooth Low Energy communication for low-power wireless applications
• Supports UART and I2C communication modes
• Supports master and slave operation
• Transparent transmission mode
• Continuous sending and receiving supported up to 115200 baud according to vendor documentation
• Effective communication distance stated as up to 80 meters under suitable conditions
• Very low power consumption compared with older Bluetooth serial module families
• Supports I/O control, PWM, RTC, advertising configuration, and app communication
• Supports low-power sleep and wake-up modes

Product overview

The JDY-16 firmware supports functions such as transparent data transmission, wireless app communication, 4-channel I/O control, PWM output control, RTC-related functions, BLE advertising configuration, master/slave communication, and multiple sleep modes.

Main technical parameters

Parameter	Value
Wireless type	Bluetooth Low Energy
Operating voltage	1.8V to 3.3V
Operating temperature	-40°C to +80°C
Communication interfaces	UART and I2C
Communication rate	Up to about 8 KBytes per second
UART continuous transceiver	Up to 115200 baud according to vendor documentation
Effective communication distance	Within about 80 meters under suitable conditions

Firmware functions

1. BLE high-speed through transmission, supporting about 8 KBytes communication rate
2. Supports 3 working modes (see sleep / startup modes below)
3. Supports serial port, I/O and app wake-up related functions
4. Supports 4-channel I/O port control
5. Supports high-precision RTC-related clock functions
6. Supports PWM functions controllable through UART, I2C and app-related control
7. Supports UART and I2C communication modes, default is UART mode

Electrical characteristics

Working mode	Broadcast state	Typical current	Remarks
Wake up	Broadcast	4mA	General communication with app connection
Deep no broadcast sleep	No broadcast	1.38uA	Very low sleep current
Light sleep broadcast	100ms broadcast interval	280uA	Average current depends on advertising interval
Average power consumption	200ms broadcast interval	140uA	Recommended broadcast interval is generally 100ms to 500ms
Average power consumption	300ms broadcast interval	80uA	Longer intervals reduce average current
Wake up state	Connected	4mA	Connected communication state
Sleep state	Connected	50uA	Sleep in connected state possible depending on mode

Broadcast interval affects both response speed and average current draw. Shorter intervals give faster discovery and connection, while longer intervals lower average current consumption.

Sleep patterns / startup modes

Mode	Instruction	Description
Sleep mode 0	AT+STARTEN0	Wake-up mode. Sleep can be controlled by AT+SLEEP. Wake-up can be controlled by the PWRC pin.
Sleep mode 1	AT+STARTEN1	Boot sleep. Wakes after connection, then returns to sleep after disconnect. In this mode the vendor notes that AT+SLEEP is invalid and sleep is controlled by the module itself.
Sleep mode 2	AT+STARTEN2	Boot sleep. Connect and disconnect are both sleep-managed. Data sent by app or serial activity can wake the module, and it returns to sleep automatically after transmission. Vendor notes that sleep is controlled by the module itself.

Communication mode selection

The JDY-16 supports both UART mode and I2C mode. The communication mode is selected through the SELECT pin.

• SELECT high or floating: UART communication mode
• SELECT low: I2C communication mode

The documentation states that the default state of SELECT is suspended / high level, so the default operating mode is UART.

Pin description

Pin	Name	Description
1	VCC	Power supply, 1.8V to 3.6V
2	PWM1	Supports UART, I2C and app control related functions
3	PWM2	Supports UART, I2C and app control related functions
4	IO4	High and low electrical level can be controlled by app
5	NULL	No connection / reserved
6	STAT	UART mode: low when not connected, high after connection. I2C mode: status / interrupt related behavior. In I2C mode, connect, disconnect or receive-data events can work in interrupt mode. Falling-edge interrupt hold time is stated as 200ms.
7	NULL	No connection / reserved
8	NULL	No connection / reserved
9	IO1	High and low electrical level can be controlled by app
10	IO2	High and low electrical level can be controlled by app
11	NULL	No connection / reserved
12	NULL	No connection / reserved
13	IO3	High and low electrical level can be controlled by app
14	PWM3	Supports UART, I2C and app control related functions
15	PWM4	Supports UART, I2C and app control related functions
16	NULL	No connection / reserved
17	ALED	Broadcast flashes, always bright after connection (master/slave effective)
18	RTCA	RTC timing pin producing a drop-edge interrupt signal, usually high level
19	TXD_OR_DD	SELECT high: UART TXD SELECT low: I2C DD
20	RXD_OR_DC	SELECT high: UART RXD SELECT low: I2C DC
21	SELECT	UART / I2C mode select pin. High = UART, low = I2C.
22	PWRC	In connected state, pull low to enter AT instruction handling. In unconnected state, this is AT command mode regardless of level.
23	RESET	Hardware reset pin
24	GND	Power ground

Communication format

The supplied documentation includes separate communication formats for I2C write and I2C read access. The I2C device address shown is 0xA0 in 8-bit notation.

I2C write format

START - 1 byte address / 7-bit address + write bit - ACK - internal function address - ACK - data N - ACK / NACK - STOP

I2C read format

START - 1 byte address / 7-bit address + write bit - ACK - internal function address - ACK - repeated addressing for read - ACK - data bytes - ACK / NACK - STOP

Notes:

• After the I2C interrupt pin is triggered, it is recommended to delay about 2ms before reading the register data.
• In I2C mode, the STAT pin can be used for interrupt-related status behavior.

I2C register map summary

	Address	Function	Length	Access
Authority	01H	APP control authority	5 bytes	Read / write
Basic	10H	Reset	1 byte	Write
Basic	11H	Search version number	11 bytes	Read
Basic	12H	Restore factory configuration	1 byte	Write
Basic	13H	Sleep	1 byte	Write
Basic	14H	Device MAC address	6 bytes	Read / write
Basic	15H	Disconnect	1 byte	Write
Basic	16H	Operating mode	1 byte	Read
Mode	C0H	Master-slave mode	1 byte	Read / write
Mode	C1H	Startup sleep	1 byte	Read / write
Master	20H	Master scan slave	1 byte	Write
Master	21H	Master binding slave	6 bytes	Read / write
Master	22H	Master gets number of slave machines to scan	1 byte	Read
Master	23H	Master connect slave	1 byte	Write
Master	24H	Master connect slave MAC address	6 bytes	Write
Broadcast	30H	Broadcast name	1-20 bytes	Read / write
Broadcast	31H	Broadcast name length	1 byte	Read
Broadcast	32H	Broadcast interval	1 byte	Read / write
Broadcast	34H	Broadcast switch	1 byte	Read / write
Broadcast	35H	Transmit power	1 byte	Read / write
Broadcast	36H	Broadcast indicating LED light switch	1 byte	Read / write
Password	40H	Connect password switch	1 byte	Read / write
Password	41H	Connect password	6 bytes	Read / write
ID type	60H	Device type	1 byte	Read / write
ID type	61H	Manufacturer identification code	1 byte	Read / write
iBeacon	70H	iBeacon UUID	16 bytes	Read / write
iBeacon	71H	iBeacon MAJOR	2 bytes	Read / write
iBeacon	72H	iBeacon MINOR	2 bytes	Read / write
iBeacon	73H	iBeacon SIGN	1 byte	Read / write
Bluetooth UUID	80H	Bluetooth service UUID	2 or 16 bytes	Read / write
Bluetooth UUID	81H	Bluetooth feature UUID (notify write)	2 or 16 bytes	Read / write
Bluetooth UUID	82H	Bluetooth feature UUID (write)	2 or 16 bytes	Read / write
Bluetooth UUID	83H	Length selection of UUID	1 byte	Read / write
RTC	90H	RTC switch	1 byte	Read / write
RTC	91H	RTC time	6 bytes	Read / write
PWM	95H	PWM frequency	2 bytes	Read / write
PWM	96H	PWM switch	1 byte	Read / write
PWM	97H	PWM1 pulse width	1 byte	Read / write
PWM	98H	PWM2 pulse width	1 byte	Read / write
PWM	99H	PWM3 pulse width	1 byte	Read / write
PWM	9AH	PWM4 pulse width	1 byte	Read / write
Communication	F0H	I2C writes data to app	1-250 bytes	Write
Communication	F1H	Read the data length sent by app	2 bytes	Read
Communication	F2H	Read the data sent by app	1-250 bytes	Read
Master search equipment MAC	E0H	Read master scan list 0 device MAC	6 bytes	Read
Master search equipment MAC	E1H	Read master scan list 1 device MAC	6 bytes	Read
Master search equipment MAC	E2H	Read master scan list 2 device MAC	6 bytes	Read
Master search equipment MAC	E3H	Read master scan list 3 device MAC	6 bytes	Read
Master search equipment MAC	E4H	Read master scan list 4 device MAC	6 bytes	Read
Master search equipment MAC	E5H	Read master scan list 5 device MAC	6 bytes	Read
Master search equipment MAC	E6H	Read master scan list 6 device MAC	6 bytes	Read
Master search equipment MAC	E7H	Read master scan list 7 device MAC	6 bytes	Read
Master search equipment MAC	E8H	Read master scan list 8 device MAC	6 bytes	Read
Master search equipment MAC	E9H	Read master scan list 9 device MAC	6 bytes	Read

AT instruction set summary

Instruction	Function	Notes
AT+PERM	APP permission configuration	Shown as slave-related function
AT+RST	Reset	Master / slave
AT+MASTEREN	Master-slave setting	Default shown as slave
AT+MAC	Device MAC	Master / slave
AT+BAUD	Baud rate	Default 9600
AT+NAME	Broadcast name	Default JDY-16
AT+NL	Long broadcast name	Default JDY-16
AT+NF	Temporary broadcast name, does not store to flash	Reverts after power cycle
AT+CONN	Master connect slave	Master mode
AT+SCAN	Master scan slave	Master mode
AT+BAND	Master binding slave MAC	Default 000000000000
AT+USTP	Serial port stop bit	Default 0
AT+SLEEP	Sleep	Master / slave
AT+PARITY	Serial port parity check bit	Default 0
AT+PASS	Slave connection password	Default 123456
AT+STARTEN	Start working mode	Default 0
AT+DEFAULT	Restore factory configuration	Master / slave
AT+FLOWC	Serial port flow control	Default 0
AT+VER	Version number	Master / slave
AT+ISCEN	Slave connection password switch	Default 0
AT+WXSVR	WeChat Airsync H5 or server related function	Transparent transmission related
AT+WXINEN	Manual and automatic test of Airsync related function	Transparent transmission related
AT+CLSS	Device style	Default A0
AT+VID	Manufacturer ID identification code	Slave-related
AT+MAJOR	iBeacon MAJOR value	Default 0A
AT+MINOR	iBeacon MINOR value	Default 07
AT+IBUUID	iBeacon UUID value	Default shown in vendor table
AT+IBSING	iBeacon SIGN value	Default 40
AT+SVRUUID	Bluetooth service UUID	Default FFE0
AT+CHRUUID	Bluetooth feature UUID	Default FFE1
AT+ADVIN	Broadcast interval	Default 1
AT+ADVEN	Broadcast switch	Default 1
AT+RTCOPEN	RTC switch	Default 0
AT+RTCD	RTC time read and write	Default date shown as 2016-01-01 00:00:00
AT+POWR	Transmitting power	Default 1
AT+DISC	Disconnect	Slave-related
AT+STAT	Connection state	Default 00
AT+ENLOG	State output enable	Default 0
AT+PWMFRE	PWM frequency	Default 1000
AT+PWMOPEN	PWM switch	Default 0
AT+PWM1PUS	PWM1 pulse width	Default 10
AT+PWM2PUS	PWM2 pulse width	Default 10
AT+PWM3PUS	PWM3 pulse width	Default 10
AT+PWM4PUS	PWM4 pulse width	Default 10
AT+ALED	Broadcast indicating LED switch	Default Open
AT+FUNC	Master controls slave IO or PWM	Marked as new function in table
AT+NETIN	Module communication enable with low-rate BLE	Marked as new function in table
AT+CHRUUID	App writes UUID to modules	Additional entry shown in vendor table
AT+WXP	WeChat steps, distance, calories	Marked as new function in table
AT+WXT	WeChat sport target (step number)	Marked as new function in table
AT+UUIDLEN	16-bit or 128-bit UUID selection	Marked as new function in table

AT commands sent through the serial port must include the required instruction format. Commands are case-sensitive.

Factory default parameters

1. Communication mode: UART (SELECT pin suspended / default high)
2. Serial port baud rate: 9600
3. Sleep mode: switch on sleep, connect to wake up
4. Default name: JDY-16
5. Broadcast interval: 200ms
6. Master-slave mode: passthrough from machine
7. Output state: connection or disconnect state output from the serial port
8. Broadcast LED indicator enabled

Practical integration notes

• The module is intended for 1.8V to 3.3V systems. Do not connect directly to 5V logic without proper level shifting.
• Default mode is UART. For I2C operation, the SELECT pin must be pulled low.
• The dual-use communication pins change function depending on the selected mode.
• After parameter changes, restart the module for reliable application of the new settings.
• In I2C mode, observe the documented delay after interrupt before reading register data.
• Because production batches may vary in firmware revision, real-world testing of the required command set is recommended before final product integration.

Summary

The JDY-16 is much more than a simple BLE serial adapter. In addition to transparent UART communication, it supports I2C register-based control, configurable advertising, master/slave roles, app-controlled I/O, PWM outputs, RTC-related functions, low-power sleep modes, and a broad AT command set. This makes it suitable for custom wireless embedded designs where both low power consumption and expanded control features are important.