3.1.2. OCT Calibration Block
There are two OCT calibration blocks for each GPIO bank. Every OCT calibration block can calibrate the I/O buffers located in the same row but not the I/O buffers in a different row. Example, the OCT calibration block in bank 2A can be used to calibrate the I/O buffers in banks 2A, 2B, 2C, and 2D but not the I/O buffers in banks 3A, 3B, 3C, and 3D.
Each OCT calibration block can calibrate two RS OCT and two RT OCT settings for all I/O standards except for the POD12 I/O standard. When using the POD12 I/O standard, each calibration block can calibrate one RS OCT and one RT OCT for the POD12 I/O buffer, and one RS OCT and one RT OCT for other I/O standards.
The OCT calibration process uses the RZQ pin that is available in every calibration block in a given I/O bank for series-calibrated and parallel-calibrated terminations:
- Each OCT calibration block has an external 240 Ω reference resistor associated with it through the RZQ pin.
- Connect the RZQ pin to GND through an external 240 Ω resistor.
- The RZQ pin shares the same VCCIO_PIO supply voltage with the I/O bank where the pin is located.
- The RZQ pin is a dual-purpose I/O pin and functions as a general-purpose I/O pin if you do not use the calibration circuit.
- Only the 1.2 V VCCIO_PIO bank can use the OCT calibration block.
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