Important ADC notes

What HAL_ADC_START_IT() does:
- It doesn't directly start the ISR, instead it
  - Starts the ADC conversion in interrupt mode
  - Enables the ADC interrupt so that when the conversion completes, the ADC peripheral will trigger an interrupt
  - The ISR - specifically HAL_ADC_CONVCpltCallback() - is then called automatically by the HAL when the conversion finishes
Comparing it ot HAL_ADC_Start:
- HAL_ADC_Start():
  - Starts ADC conversion in Polling Mode
  - CPU waits (blocks) until conversion is complete
  - You manually call HAL_ADC_GETValue() to retrieve the result
  - No ISR is involved
  - Must be called again after each conversion if not in continuous mode
- HAL_ADC_START_IT():
  - Starts ADC conversion in Interrupt Mode
  - CPU continues executing other code - non-blocking
  - When converesion completes, ADC triggers an interrupt
  - HAL calls your HAL_ADC_ConvCpltCallback() ISR
  - You typically read the result insdie that callback
  - Also needs to be called again after each conversion unless continuous mode is enabled
Blocking Operation:
- The CPU waits until the operation finishes
- It does nothing else during that time
- Example: HAL_ADC_Start() followed by HAL_ADC_PollForConversion() — the CPU sits and waits for the ADC to finish before moving on.
- Analogy: Like standing at a microwave waiting for your food - you're not doing anything else until it's done
Non-Blocking Operation:
- The CPU starts the operation then moves on immediately
- When the operation finishes, it notifies the CPU (via interrupt or callback)
- Example: HAL_ADC_Start_IT() — ADC runs in the background, and the CPU keeps working until the ISR fires.
- Analogy: Like setting atime on the oven and going to do laundry - the oven beeps when it's done, and you respond then
Blocking is simpler to implement, but it wastes CPU cycles
Non-Blocking is efficient and let's you multitask - ideal for real-time systems or juggling multiple peripherals
DMA: Direct Memory Access
- hardware feature that let's peripherals (like ADCs) transfer data directly to memory - without involving the CPU
- HAL_ADC_Start_DMA():
  - The ADC starts converting
  - DMA controller watches the ADC
  - As soon as a conversion completes, DMA automatically copies the result into a buffer in RAM
  - The CPU is never blocked, and no ISR is needed for each sample
  - When the buffer is full (or transfers completes) DMA triggers an interrupt - and you anlde it with HAL_ADC_ConvCpltCallback() or HAL_ADC_ConvHalfCpltCallback()
Polling: Best for simple, one shot reads
Interrupt: Best for event driven sampling
DMA: Best for high-speed, multichannel, contiuous sampling

Prep for Testing 8

Prep for Testing 9

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