SPRUJ55D September 2023 – July 2025 AM263P2 , AM263P2-Q1 , AM263P4 , AM263P4-Q1
In 28-bit shift in mode, the device-level, general-purpose input pin PRU<n>_DATAIN is sampled and shifted into a 28-bit shift register on an internal clock pulse. The register fills in LSB order (from bit 0 to 27) and then overflows into a bit bucket. The 28-bit register is mapped to pru<n>_r31_status[0:27] and can be cleared in software through the PRU_ICSS_GPCFG0[13] PRU0_GPI_SB register (PRU0 or PRU1).
Note that by default, the PRU will continually capture and shift the DATAIN input when the GPI mode has been set. However, clearing the PRU_ICSS_GPCFG0[1] PRU0_GPI_SHIFT_EN bit will freeze the shift operation.
The shift rate is controlled by the effective divisor of two cascaded dividers applied to the PRU-ICSS<n>_CORE_CLK clock (200MHz). These cascaded dividers can each be configured through the PRU-ICSS CFG register space to a value of {1, 1.5, …, 16}. Table 7-42 shows sample effective clock values and the divisor values that can be used to generate these clocks.
| Generated clock | PRU0_GPI_DIV0 | PRU0_GPI_DIV1 |
|---|---|---|
| 8-MHz | 12.5 (17h) | 2 (02h) |
| 10-MHz | 10 (12h) | 2 (02h) |
| 16-MHz | 16 (1Eh) | 1 (00h) |
| 20-MHz | 10 (12h) | 1 (00h) |
The 28-bit shift mode also supports the following features: