Enabling Boot Mode

The Boot Mode, or sometimes called Download Mode, is necessary to change the operating system on your board. In this mode you’re able to flash the eMMC disk.

To bring your device into Boot Mode, place a jumper to connect the Boot Mode pins.

For normal boot, please check that the bootmode jumper is open.

JP1 pin mapping

Boot Mode jumper in place

JP1 is used to configure the boot mode and the JTAG topology.

JP1 pin mapping

JP1 pin mapping

There is only one JTAG on the chip, and two JTAG modes are supported. Between these modes is selected via the JTAG_MOD pin:

Mode JTAG_MOD Function
Debug mode 0 DAP is the only TAP controller in the daisy chain. SJC will be attached to JTAG-AP of DAP.
Test mode 1 SJC is the only TAP controller in the daisy chain. 1149.1-compliant, and support 1149.6 AC coupled test.

Do not touch the test mode pin!