The boot mode for the SK EVM board is defined by two banks of switches SW2 and SW3 or by the I2C buffer connected to the test automation connector. This allows for AM64x boot mode control by either the user (DIP Switch Control) or the test automation header. All the boot mode pins require at the minimum a footprint for a pull-up or pull-down resistor. Any boot mode pin that must be toggled to support a needed boot mode must have a weak pull-down resistor and a switch (416131160808 from Wurth) capable of connecting a stronger pull-up resistor. The switch will disconnect the pull-up resistor in the OFF position. For boot mode pins that are not controlled by switches, pull-up and pull-down resistor pads should be included. Various boot modes for AM64x must be controlled by the user with the help of 8-Bit DIP switches. The following boot modes are supported by SK EVM:

• OSPI
• MMC1 - SD-Card
• CSPW Ethernet
• USB devices

The boot mode pins of the SoC have associated alternate functions during normal operation. Hence isolation is provided using Buffer ICs to cater for alternate pin functionality. The output of the buffer is connected to the bootmode pins on the AM64x and the output is enabled when the bootmode is needed during a reset cycle. The input to the buffer is connected to the DIP switch circuit and to the output of an I2C buffer set by the test automation circuit. If the test automation circuit is going to control the bootmode, all the switches will manually be set to the OFF position. The bootmode buffer should be powered by an always on power supply to ensure that the bootmode remains present even if the SoC power is cycled..

Table 4-7 provides guidance to select the boot mode before the device is powered up.

• BOOT-MODE [0:2] – Denote system clock frequency for PLL configuration. By default this bits are set for 25 MHz.

Table 4-8 gives details ON PLL reference clock selection.

• BOOT-MODE [3:6] – This provides primary boot mode configuration to select the requested boot mode after POR, that is, the peripheral/memory to boot from. Table 4-9 provides primary boot device selection details.

• BOOT-MODE [10:12] – Select the backup boot mode, that is, the peripheral/memory to boot from, if primary boot device failed.

Table 4-10 provides backup boot mode selection details.

• BOOT-MODE [9:7] – These pins provide optional settings and are used in conjunction with the primary boot device selected.

Table 4-11 gives primary boot media configuration details.

• BOOT-MODE [13] – These pins provide optional settings and are used in conjunction with the backup boot device devices. Refer to the TRM for more details on bit details. Switch SW2.6 when ON sets 1 and sets 0 if OFF.

• BOOT-MODE [14:15] – Reserved.

Table 4-12 provides backup boot media configuration options.