SPRABJ8B September 2022 – November 2023 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , AM263P4 , AM263P4-Q1
Each SOP bootmode selection signal is multiplexed with a subset of OSPI/QSPI and SPI peripheral functional mode signals. For all signal descriptions, see the Signal Description tables in the AM263x Sitara™ Microcontroller Data Sheet and AM263Px Sitara™ Microcontroller Data Sheet. The SOP signal descriptions are excerpted in Figure 5-1.
AM263x/AM263Px Pin Number | Primary Pinmux Signal | SOP Mode Signal |
---|---|---|
N1 | OSPI0/QSPI0_D0 | SOP[0] |
N4 | OSPI0/QSPI_D1 | SOP[1] |
A11 | SPI0_CLK | SOP[2] |
C10 | SPI0_D0 | SOP[3] |
Because of this SOP/functional-mode multiplexing additional care must be taken in schematic and layout to ensure that the SOP mode selection resistors, jumpers or switch paths are routed in such a way that the SOP mode branches do not present inductive stubs to the functional mode signal paths. Failing to take care of this may result in non-functional OSPI/QSPI or SPI interfaces.
In the AM263x and AM263Px Control Card and Launchpad designs this SOP mode isolation is accomplished by including a 10KΩ resistor in the SOP signal path. The resistor is placed such as one pad is as close to the AM263x BGA pad and in-line with the functional mode path. This creates a layout where the additional stub length necessary to breakout the SOP path will only minimally impact the functional mode operation of the signals, as shown in Figure 5-2 and Figure 5-3.