SWRA466D February 2015 – August 2021 CC1310 , CC1310 , CC1352R , CC1352R , CC2538 , CC2538 , CC2620 , CC2620 , CC2630 , CC2630 , CC2640 , CC2640 , CC2640R2F , CC2640R2F , CC2640R2F-Q1 , CC2640R2F-Q1 , CC2642R , CC2642R , CC2642R-Q1 , CC2642R-Q1 , CC2650 , CC2650 , CC2650MODA , CC2650MODA , CC2652R , CC2652R , CC2652R7 , CC2652R7 , CC2652RB , CC2652RB , CC2652RSIP , CC2652RSIP
The built-in bootloader on the CC2538, CC26x0, and CC26x2 devices start running after a power-on reset if there is no valid application image in flash, determined by an “image valid” field in the customer configuration area (CCA/CCFG). For more information about the "image valid" field in CCA/CCFG, see the CC2538 ROM user's guide , the CC13x0, CC26x0 SimpleLink™ wireless MCU technical reference guide , and the CC13x2, CC26x2 SimpleLink™ wireless MCU technical reference manual.
Alternatively, the bootloader start if the so-called bootloader backdoor is enabled and the associated pin that opens the backdoor is set to the correct logic level. If the bootloader is activated, it is ready for communicating with an external host 10 ms after power-on-reset.
Since the CC2538, CC26x0, and CC26x2 ROM bootloaders support commands that can read the flash, it is also possible to disable the bootloader entirely for security reasons. The bootloader and backdoor functionality is configured in the CCA/CCFG.
Figure 2-1 shows as simplified flow chart for the CC26x0 and CC26x2 boot code. The flow is similar for CC2538 devices.