6.30. Wrap up

You have walked through the parts of the machine module that come up the moment a script talks to the physical world:

  • GPIO output and input – driving an LED or a transistor, reading a button or a limit switch. The building blocks every hardware project rests on, with pull resistors and software debouncing for reads that have to be reliable.

  • Analog signals – reading a sensor, a potentiometer, or any other continuously-varying voltage with the ADC; and, when no DAC is available, producing a controlled voltage with PWM and a low-pass RC filter.

  • PWM applications – dimming an LED, varying the speed of a DC motor through an H-bridge, positioning a servo. One waveform, different physical averagers (the eye, the motor’s inductance) and different framings (duty cycle versus absolute pulse width).

  • Serial buses – UART for asynchronous point-to-point links; SPI for fast on-board peripherals with one chip-select per device; I2C for slow multi-device sensor buses on just two wires; CAN for robust multi-master field buses between modules.

  • Production patterns – a watchdog timer to recover from hangs, sleep modes to stretch a battery. Both become essential the first time a camera leaves the bench.

That is enough to build the sense – plan – act loop of an embedded device: read sensors over I2C / SPI / ADC, make decisions in Python, drive actuators through PWM / GPIO, report status over UART / CAN, sleep between events.

6.30.1. Using this reference later

Treat the hardware chapters as reference material, not a one-pass read. The machine module reference page lists every class and method in one place when the question is just “what is the exact name of this call”. The per-chapter pages here are where to come back for the “which knob does what, and why” view that the reference material does not give on its own.

6.30.2. Where to go from here

Vision sensors is the next major topic. Where this section taught the generic peripherals – Pin, ADC, PWM, UART, SPI, I2C, CAN – that show up on almost any MCU, the next section teaches the camera’s defining peripheral very deeply: the image sensor, and the long chain of optics, silicon, and signal processing between photons hitting glass and a buffer of pixels in RAM. The toolkit shifts to the csi and image modules, but everything you have learned about driving GPIOs, talking over I2C, and using PWM carries forward unchanged – strobes, triggers, and sensor shields all use the same buses you have just covered.