Good Sunday morning.
I am currently working on a project with:
- Arduino Pro Mini 3.3V
- HC-06 Bluetooth Module
- 3.7V Li-Ion battery (Lithium Ion Battery - 850mAh - PRT-13854 - SparkFun Electronics )
- 3V "pancake" vibrator motor
- Seeed Studio inductive charging module (https://www.seeedstudio.com/Wireless-Charging-Module-5V-1A-p-1912.html)
I control the vibrator motor over Bluetooth using MIT App Inventor 2 (AI2). I use PWM and analogWrite from the Arduino Pro Mini to a transistor which in turn allows current to flow from the 3.7V power supply through the vibrator motor with flyback diode and then to ground.
The main issue that I am having is that the HC-06 loses power when the battery power dips below 3.6V, as it should, and then it CANNOT be restarted.
The Vcc for the HC-06 is 3.6 to 6V. When the Li-Ion battery is fully charged , it tops out at about 4.6V. So this should not be a problem for the HC-06. But when the voltage dips below 3.6V, there is not enough "juice" to supply the 3.3V on-board voltage regulator and the red LED on the HC-06 stops blinking. But even if I place the transmitting inductive charging coil over the receiving charging coil, I CANNOT GET THE HC-06 TO RESTART. It essentially goes dead. I have checked the voltage at the HC-06 voltage regulator and it is 3.3V even when the red LED has stopped blinking. But the Pro Mini stays remains illuminated.
I have swapped out HC-06 modules a couple of times. I have powered up the ones that I have removed using my benchtop power supply and they pair and connect.
The Seeed Studio inductive charging module charges up to 5V/1A. Does this charging coil have internal circuitry that will stop charging the battery once it achieves a full charge, even if it is under 5V?
How do I jumpstart the HC-06?
Please see the attached circuit diagram.
By the way, I have Arduino Vcc connected to Arduino PIN A0 so that I can monitor voltage. And I have HC-06 TX pin connected to Arduino PIN 8 (for AltSoftSerial) and I also connect this to PIN 2 as I was trying to use create an interrupt once the voltage level changed.