4/29/26: Remote car control, kinda

Combined previous TCP, socket functionality with motor code
One motor is moving faster than the other…
Latency is slow too, although remote blink was really fast. might look into bridge latency on arduino
only had like 15 minutest today before i got kicked out of the bme lab haha. gotta find another lab to work in now.

4/28/26: Got one car fully working

Forward, backward works. Left, right does not
Strange, because left, right is just one motor turning and the other stopping, and one motor worked yesterday.
Used oscilliscope to debug the input pins of 74HC595 shifter, looked right. Probed L293D and noticed enable pin mismatch with the 2 input signals. (Enable pin driving one motor, where the corresponding input signals drove the other)
Realized that AI mode was wrong, and upon reading a FAQ in the motor shield website, I flipped the digital pins 😅: digital pin 5 should be connected to motor 3 that corresponds with pin 0 and 6 on the serial shifter, and digital pin 6 connected to motor 4 with pin 5 and 7 correspondence.

Forward worked, backward worked. but consecutively, they don’t work.
oscilloscoped the clock line. didn’t see anything useful, just a vibrating line at 0.3V. Added some delays in the clock line and now the oscilloscope picked up the correct clock line.
started commenting out section by section until I narrowed down the issue to analogWrite(M1_PWM, 255)
apparently, M1_PWM on D11, actually affects and disables my latch pin on D12 for some reason. Looked online, and apparently, some peripheral issues can occur with specific pins when you set them to analog mode.
I switched it to digitalWrite(M1_PWM, HIGH) , and it worked. also switched the analog write to another pin that wasn’t near any used pins and could do PWM’s and it worked.

Tried to use L293D motor shield on Arduino Uno Q instead of Uno R4 Wifi - did not work.
Checked hardware compatibility - uno q output 3.3V, l293D accepts ~2.3V as high - no issue
some arduino pin issue when i ran the code, software compatibility issue maybe
read the schematics for l293d and 74HC595 shifter and coded up the custom library. learned how they work, including pwm, latch, clock, and serial shifting. soldered up everything including batteries, motors, switches. did not work.
checked batteries and motors - both ok.
kept minimizing code logic until I realized I didn’t have latch_state=0 to reset the latch state prior to updating it using boolean logic.

Takeaway: schematics are guides, not guarantees. Always validate with real signals.