Device Boot Modes
539
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
ROM Code and Peripheral Booting
Bits 24:31
Bits 16:23
Bits 8:15
Bits 0:7
Bmode_pin4
Bmode_pin3
Bmode_pin2
Bmode_pin1
To change the default boot mode pin to GPIOx, program GPIOx+1 in the corresponding bit field.
Bmode_pin1 (bits 0:7)
The default pin1 boot mode pin is PG3_GPIO43. For example, if the user wants to choose
PA2_GPIO2, then program bits 0:7 with 0x3 (decimal 3).
Bmode_pin2 (bits 8:15)
The default pin2 boot mode pin is PG7_GPIO47. For example, if the user wants to choose
PF2_GPIO34, then program bits 8:15 with 0x23(decimal 35).
Bmode_pin3 (bits 16:23)
The default pin3 boot mode pin is PF3_GPIO35. For example, if the user wants to use the
same default pin3 boot mode pin (PF3_GPIO35), then leave bits 16:23 unprogrammed.
Bmode_pin4 (bits 24:31)
The default pin4 boot mode pin is PF2_GPIO34. For example, if the user wants to choose
PC5_GPIO69, then program bits 24:31 with 0x46 (decimal 70).
CAUTION
Once programmed, the OTP BOOTMODE GPIO CONFIG register CANNOT be
erased. So, program this location ONLY if you have finalized the GPIO.
Restrictions:
•
The chosen boot mode pins should be between GPIO0 and GPIO71. In case of any illegal GPIO entry,
boot ROM defaults to factory-selected boot mode pins.
•
The following GPIOs (GPIO39, GPIO44, GPIO64, GPIO65, GPIO66, GPIO67) cannot be used as boot
mode pins, as these pins are not pinned out on this device. Selecting these pins as boot mode pins is
considered an illegal GPIO entry.