1. Configure a pin that will activate the SBL mode when a chip starts.
   
2. First time, flash firmware using a J-Link flasher or XDS-110 proble.
3. The firmware assumes that the active state is LOW (connected to GND).
4. Assumed that you can connect your chip to a computer using a UART-USB stick or corresponding schematics on your DIY board. Chips may use different pins for SBL UART.
   
   
   
   
5. Press and hold the Reset button or disconnect power.
6. Press and hold the SBL button.
7. Unpress the Reset button or connect power.
8. Start serial flashing utility (author’s page) from a command line.

cc2538-bsl_x64.exe -p COM18 -ewv "c:\path_to\firmware.hex"

COM18 – replace it with your COM port number. You can find it in Devices Manager.
firmware.hex – your firmware file with a full path.

The normal uploading process will look like this:

Invoking bootloader by method 1 (default)
Opening port COM18, baud 500000
Reading data from firmware.hex
Your firmware looks like an Intel Hex file
Connecting to target…
CC1350 PG2.0 (7x7mm): 352KB Flash, 20KB SRAM, CCFG.BL_CONFIG at 0x00057FD8
Primary IEEE Address: 00:12:4B:00:24:C0:F3:49
Performing mass erase
Erasing all main bank flash sectors
Erase done
Writing 360448 bytes starting at address 0x00000000
Write 104 bytes at 0x00057F988
Write done
Verifying by comparing CRC32 calculations.
Verified (match: 0x7d5e5a99)

Flash Programmer 2

You can also use Texas Instruments Flash Programmer 2 v 1.8.2 and higher (you’ll need a free account to download a file).

1. Select the UART port assigned to your CC2652 chip.
2. Select the chip type.
3. Select the firmware file.
4. Select programming options (Erase – Program – Verify).
5. Click the “Start” button.
6. Check a status.