6.2.2.7 Capture Unit
The capture unit provides a logging function for different events or transitions. The values of the selected GP timer counter is captured and stored in the two-level-deep FIFO stacks when selected transitions are detected on capture input pins, CAPx (x = 1, 2, or 3 for EVA; and x = 4, 5, or 6 for EVB). The capture unit consists of three capture circuits.
Capture units include the following features:
- One 16-bit capture control register, CAPCONx (R/W)
- One 16-bit capture FIFO status register, CAPFIFOx
- Selection of GP timer 1/2 (for EVA) or 3/4 (for EVB) as the time base
- Three 16-bit 2-level-deep FIFO stacks, one for each capture unit
- Three capture input pins (CAP1/2/3 for EVA, CAP4/5/6 for EVB)—one input pin per capture unit. [All inputs are synchronized with the device (CPU) clock. In order for a transition to be captured, the input must hold at its current level to meet the input qualification circuitry requirements. The input pins CAP1/2 and CAP4/5 can also be used as QEP inputs to the QEP circuit.]
- User-specified transition (rising edge, falling edge, or both edges) detection
- Three maskable interrupt flags, one for each capture unit
- The capture pins can also be used as general-purpose interrupt pins, if they are not used for the capture function.