How do you pass data from an ISR to a task?

Use a queue's FromISR API: in the interrupt handler, after reading the data from the peripheral, call xQueueSendFromISR(queue, &item, &higherPriorityTaskWoken) to enqueue it, then on ISR exit call portYIELD_FROM_ISR(higherPriorityTaskWoken) so that if the send unblocked a higher-priority task, the scheduler switches to it immediately. A consumer task sits blocked on xQueueReceive(queue, &item, portMAX_DELAY) and wakes to process each item. This is the deferred-interrupt pattern carrying a payload: the ISR stays minimal (read the byte/sample, enqueue, return), and the actual processing happens in a task that's blocked (using no CPU) until data arrives. The mandatory rules are that you must use the FromISR variant (the normal xQueueSend cannot be called from interrupt context), you must not call any blocking or non-FromISR API in the ISR, and you keep the ISR short. If items can arrive faster than the task drains them, the queue depth must be sized to absorb the worst-case burst, or you decide a drop/overwrite policy. This is the same structure as signaling with a semaphore-from-ISR, except the queue conveys the actual data, not just the fact that an event occurred.