Article ID: 000081654 Content Type: Troubleshooting Last Reviewed: 09/11/2012

Can I boot an Excalibur device from the flash in an EPC16 device?


Description Yes, you can boot an Excalibur device from the flash in an EPC16 device. However, in order to have access to flash directly at reset, which is needed for boot from flash, the TM0 and TM1 pins of the EPC16 device both need to be connected to logic '0', making TM[1..0] = "00". This will disable the EPC16's flash controller, subsequently tri-stating the pins it uses to access flash and freeing them for external flash access.

Note however, that to program the EPC16 via JTAG, or to use the EPC16 for serial configuration, TM[1..0] must equal "10". So a PC board that is to support both boot from flash and either JTAG EPC16 programming or passive serial configuration, must incorporate a jumper for TM1 so that it can be connected to either logic -1- or logic -0- to support both modes.

Also note that TM1 cannot be switched while either device is running. To switch the EPC16 between boot from flash mode and normal user mode, the power must first be switched off before changing the logic state of the EPC16 pins TM1 and TM0.

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