Arduino ATtiny85 Switch

3 pin with bluetooth control

Simple low powered automation to switch 3 AC sockets and controlled by Bluetooth. #ATtiny85

Devices required

1. ATtiny85
2. DS1307 or DS3231 RTC module
3. HC-05 or HC-06 Bluetooth module
4. 3.3v to 5v power supply

ATtiny85 pins:

Pin	Name	Wire connection
1	Reset	Not connected
2	I/O Pin 3	Switch 2, BT: Tx
3	I/O Pin 4	Switch 3, BT: Rx
4	GND	Connected to Ground
5	I/O Pin 0	RTC SDA
6	I/O Pin 1	Switch 1, Mode change pin
7	I/O Pin 2	RTC SCL
8	VCC	Connected to +3.3v to +5v

Note: Mode pin should be connected to GND via 10K resistor. To enable Bluetooth mode, connect the Mode pin to VCC and need to restart the device.

Default time schedule:

Switch	On	Off
Switch 1	06:00	23:00
Switch 2	09:00	19:00
Switch 3	08:00	00:00

Note: Can be re-scheduled by changing values in t85-switch-3pin-with-BT.ino file or via Bluetooth Application.

Bluetooth Mode

To access device from bluetooth, start device in BT mode by connecting MODE pin with VCC.

For commands, have to send two bytes with 50ms gap.

-> First byte will be COMMAND
-> Second byte will be PARAMS (Values)

Command details:

Sr No	Command	Param	Return	Description
1	255	0	SAME_PARAM	Pingback. To recognize this device
2	254	0	TIMESTAMP	Get RTC time in timestamp (UTC)
3	253	TIMESTAMP	SAME_PARAM	Set RTC time, value in timestampt (UTC). Return the same as Param if success
4	252	0	1-30	Get number of switch device support. Ex. 3
5	251	ROM_ADDR	0-255	Read value from EEPROM. To read switch value. ROM_ADDR will be between 0 and (PIN_COUNT * 2)
6	251	250	0-59	Get time drift in second(s)
7	250	0-59	SAME_PARAM	Set time drift in second(s)
8	0-60	0-23	SAME_PARAM	Write value to EEPROM. Set hours to switches.

To update Switch on-off hour:

Switch	Command	Param
Swt 1 On	0	0-23
Swt 1 Off	1	0-23
Swt 2 On	2	0-23
Swt 2 Off	3	0-23
Swt 3 On	4	0-23
Swt 3 Off	5	0-23
so on...

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Best Regards,
Alauddin Ansari (GitHub Page)