Reacquaintance
Spent most of this morning wiping the cobwebs off my code and re-familiarizing myself with everything. Current functionality breakdown:
BT chip working & advertising
Gyro sensor reporting yaw,pitch,roll over I2C connection
Mobile app pairs to chip and responds to packets, chip reports a rough distance calculation using ToF
Spent the latter half of today trying to get PWM motor control working so I can hook everything up to the RC car and get a rough POC. Confirmed PWM library and logic is working correctly by dimming the LED built into the board, but unable to get motors spinning on the RC. The L298N motor controller I'm using requires power + ground to power the controller board, and uses 3 inputs to control a motor (high, low, PWM speed). I thought the 5v from the ESP32 would provide enough current to bump a motor with no load, but nothing budged. Switched controller board power/ground to the leads from the RC battery pack, which was enough to power the board signaled by a builtin LED, but again no actual movement on the motors.
Reading some reports that the motor controller I'm using can drop the power voltage by 2V, so I think next step is either a better motor controller or a converter to bump my 5v output into 12v to power the board and motors. This motor controller isn't permanent, and likely isn't beefy enough to power the endgame motors for this project anyways
May 15, 2024
Good progress today. Moved motor control responsibility to the Arduino. The ESP32 operates at 3.3V, Arduino operates at 5V. While the motor I was using can operate at 3V like the ESP32 will provide, the motor controller operates on 5V, and the 3.3V signals from the ESP32 were likely not high enough voltage to register as an input on the motor controller. The ESP32 is now signaling the Arduino when to power the motor, and the Arduino is implementing a ramp-up/ramp-down PWM speed control on the motors.
We still have to deal with the issue of different operating voltages between ESP32 and Arduino. At first, I tried sending a digital high/low signal from the ESP32 to trigger an interrupt at the Arduino to flip a boolean that was checked in the main loop to power/stop the motors, but the window of what the ESP32 considers a high signal and what the Arduino considers a high signal isn't very wide (diagram attached, 3.3V vs 5V logic levels). This worked, but the signal wasn't clean and it felt janky.
My next goal is for the ESP32 to send a 200ms pulse to a pin the Arduino, triggering an interrupt that sets a flag. The main loop will check for this flag before reading an analog input, either high or low from the ESP32 to control the motor speed. My goal with using an analog input is to take advantage of the AREF pin on the Arduino. The AREF pin accepts a reference voltage when performing ADC (Analog-to-Digital Conversion), and when provided 3.3V at the reference pin, the Arduino can consider 3.3V as HIGH when reading the value from an analog input, effectively translating a 3.3V high signal into a 5V high signal.
