This reference design showcases the Multi-Boot mode supported in Nexus devices. The Multi-Boot mode supports booting from up to six patterns that reside in an external SPI flash device, up to three patterns for MachXO5-NX internal flash memory. The patterns include a primary pattern, a golden pattern, and up to four alternate patterns, designated as Alternate Pattern 1 to Alternate Pattern 4.
For Avant devices, the Multi-Boot mode supports booting from up to eighteen patterns that reside in an external SPI flash device. The patterns include a primary pattern, a golden pattern, and up to sixteen alternate patterns, designated as Alternate Pattern 1 to Alternate Pattern 16.
By using Multi-Boot mode, you can combine all the bitstream patterns into a single bitstream image and store it in a single external SPI flash device. This solution decreases cost, reduces board space, and simplifies field upgrades. Note that this reference design is developed using the CrossLink™-NX and Avant™-X70 device, but the design can be ported to other Nexus devices.